AQ140/280 mystery problems after outdrive rebuild--acts like wrong gear ratio but isn't!

I've got two major problems after I had my late 70's outdrive rebuilt. I ran a combo rebuilt AQ140 (converted to a Weber carb & pertronix) with the original 280 outdrive for nearly 400 hours. All this on a '79 Campion 17-1/2'.
The owner before me had installed a stabilizer fin--Doel-Fin I think (I got the boat about 8 years ago). The boat would get on plane in 5 or 6 seconds and hold a straight course (In calm seas) with hands off the wheel for several seconds at least. Nice running, balanced boat...I run Northern Puget Sound, San Juan Islands exclusively.
Because of a hole in my drive bellow, I pulled everything apart and replaced seals, bearings, etc, and because of a little saltwater intrusion in the upper housing/clamp ring, decided to let a local guy do a complete rebuild.
I gave him my original 280 and another 280 "parts" outdrive. Said I wanted one "like new" in return.
Long story short. I re-installed the outdrive, checked and rechecked everything and took off for a few days fishing with a friend yesterday morning.
COULD NOT GET ON PLANE and the boat PULLED HARD TO PORT (left). Every time I tried applying more throttle, it would bog down. Acted like it had a prop a few inches to big! I run a 14 x15 right-hand prop, same as I ran with my original set up. We switched to my spare prop--no difference. Before, I could get over 5k W.O.T. with an average load.
We changed the little "steering fin" both ways on the outdrive-and the manual trims tabs, no noticeable change in handling.
We moved all the gear far forward along with my friend. After about 4 or 5 minutes I could get on plane--at around 3200-3300. From there I could get 4000rpm-4100rpm MAX. It was like pulling an anchor or two. All the while a HARD PULL to Port. Higher speed, the harder the pull to the left.
The rebuild guy used different housings, etc. during the rebuild. Also, we left the "Doel-Fin" off. I thought for sure he used the wrong gear ratio in the lower.. Nope, I pulled the lower this morning, got 2.15:1(or darn close) by rotating the input shaft and checking the prop rotation. I then reconnected it, pulled the entire outdrive off and checked the ratio again--turning the input shaft (with U-joints) and measuring that against the prop rotation. Still go 2.15:1 which is correct for this older AQ 4cyl.
Noticed the new oil, when I just drained it was a med to darker grey with some silvery-brass sheen in it-not clean like I expected it to be. I saw the pressure test before I paid for the rebuild--held 15 lbs for at least 5 minutes).

How can these problems develop?? Pulling hard to port AND, engine bogs down won't get on plane--like starting a car in 3rd or 4th gear. Remember, we tried 2 proven props. Engine out of gear revs right up, doesn't miss a beat up to a very brief 5k plus.
MYSTERY, I cannot figure this one out. The guy who did the rebuild has done them for 25 years, he can't figure this out either. Has ANYONE ever encountered something like this?

A 2.15:1 drive rarely requires a rebuild. The four-cylinder engine just simply does not have enough power to harm one!
At worst, unless it was terribly corroded…, it should have required a reseal only.

Keep in mind that when physically checking the over all gear ratio by counting input revolutions, the sliding sleeve must be locked into the gear cup prior to your rotational test.


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Hi Rick,
I agree with you about the 280 not needing rebuilds often. That said, when the drive bellows failed and salt water got into the clamping ring, etc.some rust worked it's way in to the shims, etc.. Also we had a difficult time pulling the driveshaft (PDS) out of the back end of the bellhousing. Had the upper gear housing off and the intermediate housing covered while snapping a big chain to jerk that stuck shaft out. Even though we had it covered with layers of rags, the chain beat up the top on the intermediate housing--you get the picture. I had a spare 280 (off a 4 cyl) sitting around for years of unknown hours--but it looked good on the outside. Installed that one and it made some bad noises during my water test. So, back to square one and started mixing and matching housing to get one good unit. I wanted the shims and everything else to be set up correctly hence the total rebuild by someone who knew how to do it correctly. That's my story (The short version) and I'm sticking to it! (add a smile)

Now, by locking the sliding sleeve do you mean shifting it into gear? Is the "sliding sleeve" the same as the brass "cone clutch"? I put it in gear and got the same readings each time. If it wasn't locked wouldn't I get different readings each time

I don't like the color of your oil. You may have a bearing binding up or the sliding sleeve is slipping in the cups. There should be no, nada, brass transfer on the cups from the sliding sleeve. This happens but not to often. Problem is to check this, the upper has to be pulled and torn down again. I'd almost go with a bearing being bad.

Hi Gary,

Yep, that dirty oil with aluminum or brass "powder" in it bothers me. That oil was fresh before I did the shake down cruise on the water. It should have drained out relatively clean and clear.
It's another clue in this weird puzzle of duel problems.
I'll run what you said by the guy who did the rebuild. Assuming that "might be" the problem, if the brass "clutch" were slipping, why wouldn't it slip while I tried to throttle up and get on plane? I didn't notice any "give" or slip at all during a few hours of testing on the water. The other part of the mystery is why does it pull SO hard to port, increasing as forward speed increases? When I finally got it on plane (Read the original post)--it was all I could do to keep it going straight. If I took my hand off the wheel for a split second it could have turned so sharp it might have put us in the water. Very weird problem.
The two things must be related but I can't figure out how. Physics must be involved--but it's beyond me. Tomorrow, I will bring the outdrive back to the guy who rebuilt it and he'll probably do a tear down on it. He said he'd stand by his work.
Any and all input from you guys who know older Volvos is gladly welcomed!

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followingsea said:

Hi Rick,
I agree with you about the 280 not needing rebuilds often.
Typically yes, unless they've been neglected.

That said, when the drive bellows failed and salt water got into the clamping ring, etc. some rust worked it's way in to the shims, etc..
In addition to rusting the steel bearing box and shims, this also rusts the carbon steel seal surface washer.
The rust then becomes abrasive, and the abrasion cuts away at the seal lip.

Also we had a difficult time pulling the driveshaft (PDS) out of the back end of the bellhousing. Had the upper gear housing off and the intermediate housing covered while snapping a big chain to jerk that stuck shaft out.
This means that the female yoke splines were rusted to the AFT end of the PDS?????

Even though we had it covered with layers of rags, the chain beat up the top on the intermediate housing--you get the picture.
The top of the Intermediate housing... or the transmission??? (I'll post more on that and the right way to do this)

I had a spare 280 (off a 4 cyl) sitting around for years of unknown hours--but it looked good on the outside. Installed that one and it made some bad noises during my water test. So, back to square one and started mixing and matching housing to get one good unit.
You are aware that critical shimming is required when we swap one component to another.... correct????

I wanted the shims and everything else to be set up correctly hence the total rebuild by someone who knew how to do it correctly.
I certainly hope that he knew what he was doing!


Now, by locking the sliding sleeve do you mean shifting it into gear?
I mean not only shifting into gear, but making sure that the sleeve remains in the gear cup while doing the ratio check.
This means that once you begin, you must not allow it to relax until you've made your 2.15 revolutions.

Is the "sliding sleeve" the same as the brass "cone clutch"?
The cone clutch is the sum of all three...... the brass sliding sleeve, and the two carbon steel gear cups on this drive.

I put it in gear and got the same readings each time. If it wasn't locked wouldn't I get different readings each time
More than likely yes.

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followingsea said:

Hi Gary,

Yep, that dirty oil with aluminum or brass "powder" in it bothers me.
I'm with Gary..... there should be no brass or aluminum contaminates in your gear oil.
Brass could only come from the sliding sleeve, and any aluminum could only come from a slinger pump rotor that has sheared the drive pins.
The aluminum rotor will shear drive pins if heavy gear oil is used in lieu of the correct 30W engine oil.
When you lose the slinger pump, the upper transmission loses it's oil cooling.


That oil was fresh before I did the shake down cruise on the water. It should have drained out relatively clean and clear.
It's another clue in this weird puzzle of duel problems.

I'll run what you said by the guy who did the rebuild. Assuming that "might be" the problem, if the brass "clutch" were slipping, why wouldn't it slip while I tried to throttle up and get on plane? I didn't notice any "give" or slip at all during a few hours of testing on the water.
If you were able to throttle up and get on plane, the sliding sleeve is NOT slipping.

The other part of the mystery is why does it pull SO hard to port, increasing as forward speed increases? When I finally got it on plane (Read the original post)--it was all I could do to keep it going straight. If I took my hand off the wheel for a split second it could have turned so sharp it might have put us in the water. Very weird problem.
Large propeller, mis-adjusted trim fin/torque tab may cause steer torque.
The 280 with it's trim fin/torque tab is typically very easy to correct steer torque with.


The two things must be related but I can't figure out how. Physics must be involved--but it's beyond me.
Agreed...... it does not make any sense to me either, and I've been doing the AQ series for 25 years.

Tomorrow, I will bring the outdrive back to the guy who rebuilt it and he'll probably do a tear down on it. He said he'd stand by his work.
Any and all input from you guys who know older Volvos is gladly welcomed!
Make sure that he did NOT mix and match gears. Each set of Volvo Penta gears are to remain together.
Make sure that he understands the rolling torque procedure and the shimming procedures for both the transmission and lower unit.


A good check to see if a mechanic actually knows the AQ series:
..... listen to what names he uses for the components.
..... see if pulls an entire drive, as apposed to pulling the transmision first, then the lower section.
..... how carefully he removes the suspension fork hinge pins. (removal can be a real bugger if you don't know what you're doing)
..... if he attempts to remove or to hang an entire drive while assembled...... he's not your guy.

Click to expand...

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Hi Rick,

Lots of things to answer here. Here's a few points without making it too long. I used straight 30 wt oil, same as I've been using for about 8 years. Yep, the female splines on the u-joint yoke had some rust and stuck on the PDS. I had a "Sealed Bearing" so there was no saltwater intrusion forward of the PDS bearing. But that's all been cleaned up, wire wheeled the surface rust to clean metal on the yoke, PDS shaft, etc. new u-joints, new seals, new sealed bearing. That part is not a concern now--all taken care of.

Yes, I'm aware that the shims need to be be done spot on and the pre-load on the bearings. That's why I took it to a guy who had 25 years doing it instead of attempting to do it myself.

At this point I'm focusing on the two main problems:
1) Hard pulling to port --with the steering fin adjust both ways and in the middle making virtually no difference, slow speed or fast.
2) Very heavy load on the motor and acting like the gearing is way off.

One thing that has run through my mind last night. I noticed the mechanic changed the lower housing. The one I currently have has a line of bolt holes across the aft portion of the exhaust port--like there was a flapper installed. Perhaps he put a 270 lower on my 280? A mismatched lower or one that somehow off slightly to one side (could it have previously been hit something hard enough to bend it just enough to cause the pulling to one side?). By looking at it, I can't see anything obviously out of line. You'd think if it was hit hard enough in the past, it would have cracked the housing, not bent it slightly?

So to point #1, The HARD PULL to PORT must be related to the lower housing, got to be. That's the portion of the outdrive that hangs below the hull. The intermediate and upper housings would have no effect of pulling to port or starboard. Is this deductive reasoning correct? I'm trying to eliminate what "isn't" causing the problem.

And to point #2, the gray and brass sheen in the oil could also be steel from bearings or whatever, instead of aluminum--but I definitely get a brass sheen in the oil, especially looking at it in the sunlight. No noticeable "clunks" and no noticeable noise (grinding, whining, etc.) in the outdrive all the time we ran it in the water--low speed or high. Except perhaps the cone clutch started "clunking" more as the trial when on. By the way, I believe the mechanic told me that he DID "mix and match" some gears.

That's enough for the reply. Believe me, I've been over the "woulda, coulda, shoulda" aspects of my dilemma/fiasco. If I could go back and do it over again, it would have been done differently. But that's water under the bridge. My original plan was to have a "professional" make my outdrive, "like new". We now know that plan didn't work out as well as I wanted. That said, I've got to deal with things as they are at present.

Back at you guys...
By the way, THANKS to you (Rick and Gary) for taking the time out of your busy lives to assist with this mystery. If it didn't have me baffled, I wouldn't be asking for help.

Volvo did in fact have some different gearing in the lower units early on. Many believe the 215, 189 and 161 are the only ones but I have seen and may have a set of 132 or close to it, in my shop. Makes me start think about your possible ratio problem.

Rick & Gary,

Here's some more info.. Just got back from spending about 4 hours with the guy who did the rebuild. Pulled the lower, intermediate and upper to have a look (without a complete tear down). He checked the gears, bearings, etc.. He laid out the lower gears for a V-6, V-8 and 4 and showed me the difference. He said the lower unit has the right gears for a 4 cyl.. Moving to the upper unit. He said VP uses the same gears up there for all the older motors. There were 26 teeth on the aft end of the input shaft (with the U-Joint assembly on the forward end) in the upper gear housing. There were 27 teeth on the bevel gear (Sits horizontally in the top of the upper gear case) that it meshes with.

Everything turned freely, nothing binding in the upper, intermediate or lower housing that we could see. He thought the gray color in the oil along with some metallic sheen was a combo of left over media from getting the cases media blasted (plastic beads hopefully) and perhaps a little fine wear on the brass cone clutch getting seated... The oil pump widget that looks a little like a turbine blade that sits behind the gear in the lower housing was checked and he said it was exactly as it should be.

We did find one slight abnormality. The skeg on the lower housing seems bent very slightly to the left (looking from the aft end). Perhaps 1/16 -1/8" maximum by "eye-balling" it. This could tend to pull the boat to the port side, but not so much that it takes all your arm power to hold a straight course. It also wouldn't explain not being able to get on plan, or having it bog down like it's way over-propped. If getting pulled to the port side were the only problem, I should have been able to get the rpm's up and get on plane in a long left-sweeping (port) turn.

So that's where we sit. We both decided to let it rest for the weekend and keep digging for answers. He said he'll log-in here a join the discussion when he gets the time. He also said he going to see if he can get some time with a VP factory guy that he knows of who has a large fund of knowledge and experience. Hopefully, that guy will help and perhaps shed some light on this mystery.

Again, the motor runs great in neutral sitting in the water. Revs up immediately--every time. When it did finally get on plane it could hold 4,000-4,100 rpms without missing a beat--but could not get any more out of it, but it was REALLY working to get that. And again, with a very strong pull to port. With the old, original sterndrive and this same AQ 140- 4 cyl. motor/prop (14x15) combo I would easily get up around 5,000+ rpms and be on plane in about 6 seconds with a load. Again this is a 17-1/2" fiberglass boat--not a big heavy cruiser.
That's what we found today, nothing definite that jumped out as a cause for these problems. Very frustrating...

The part numbers for the gear sets are on the gears. 161 832624 189 832628 215 832632. I'd double check them!!!

Gary,

Good point. Didn't know that. I'll ask the guy who did the rebuild to check the numbers. There's an answer for this mystery somewhere...

"When you have eliminated the impossible, whatever remains, however improbable, must be the truth?" Sherlock Holmes

Thanks again for the help!

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followingsea said:

Rick & Gary,

Here's some more info.. Just got back from spending about 4 hours with the guy who did the rebuild. Pulled the lower, intermediate and upper to have a look (without a complete tear down). He checked the gears, bearings, etc.. He laid out the lower gears for a V-6, V-8 and 4 and showed me the difference. He said the lower unit has the right gears for a 4 cyl..
OK.... this would be 2.15:1 but takes into account the transmission's reduction as well.
In other words....... the 2.15:1 is a final drive reduction from the combined reduction of both upper and lower units.


Moving to the upper unit. He said VP uses the same gears up there for all the older motors.
Well.... not quite so.
While the reduction may be the same, the gear sets have undergone several changes over the years.

The AQ series "E" transmission reduction is unique, but would not work with an earlier AQ series drive.

There were 26 teeth on the aft end of the input shaft (with the U-Joint assembly on the forward end) in the upper gear housing. There were 27 teeth on the bevel gear (Sits horizontally in the top of the upper gear case) that it meshes with.
That would be your main drive gear..... and two driven gears.

Everything turned freely, nothing binding in the upper, intermediate or lower housing that we could see. He thought the gray color in the oil along with some metallic sheen was a combo of left over media from getting the cases media blasted (plastic beads hopefully) and perhaps a little fine wear on the brass cone clutch getting seated...
That would be the sliding sleeve, and there should be NO wear or seating in.
In other words.... from day one the sliding sleeve should be a perfect mate to either gear cups.

(there is a lapping procedure for use with used sleeves/cups, but it will not be mentioned in any OEM service manual)

The oil pump widget that looks a little like a turbine blade that sits behind the gear in the lower housing was checked and he said it was exactly as it should be.
Good! The rotor should be fixed to the driven gear.
I call it a die cast aluminum impeller, but Volvo calls it a rotor...... and yes, it does look somewhat like a turbine impeller.

We did find one slight abnormality. The skeg on the lower housing seems bent very slightly to the left (looking from the aft end). Perhaps 1/16 -1/8" maximum by "eye-balling" it. This could tend to pull the boat to the port side, but not so much that it takes all your arm power to hold a straight course.
You may be surprised, but I can't say one way or the other.

It also wouldn't explain not being able to get on plan, or having it bog down like it's way over-propped. If getting pulled to the port side were the only problem, I should have been able to get the rpm's up and get on plane in a long left-sweeping (port) turn.
Agree.

So that's where we sit. We both decided to let it rest for the weekend and keep digging for answers. He said he'll log-in here a join the discussion when he gets the time. He also said he going to see if he can get some time with a VP factory guy that he knows of who has a large fund of knowledge and experience. Hopefully, that guy will help and perhaps shed some light on this mystery.

Again, the motor runs great in neutral sitting in the water. Revs up immediately--every time.
As much as we like it to, this doesn't mean much.

When it did finally get on plane it could hold 4,000-4,100 rpms without missing a beat--but could not get any more out of it, but it was REALLY working
to get that.
The final drive ratio could be incorrect. It may not be a 1.61:1 gear set ..... but perhaps it could be a 1.89:1 gear set.

And again, with a very strong pull to port.
That's what I'm having trouble with.

With the old, original sterndrive and this same AQ 140- 4 cyl. motor/prop (14x15) combo I would easily get up around 5,000+ rpms and be on plane in about 6 seconds with a load. Again this is a 17-1/2" fiberglass boat--not a big heavy cruiser.
That's what we found today, nothing definite that jumped out as a cause for these problems. Very frustrating...


Check list:

280 style ring anode in place... correct?
280 spacer/line cutter in place? (the long one, not the short one)
Same prop as before... no changes?

Trim fin/torque tab correct for the 280?
Boat pulls to Port.... trim fin/torque tab is turned towards Port.... correct?
And visa-versa if the boat was to pull to Stbd.

Main suspension fork hinge pins both good?
Main suspension fork in good condition? (no cracks/fractures)

I too will keep my thinking cap on over the weekend.

Click to expand...

followingsea said:

"When you have eliminated the impossible, whatever remains, however improbable, must be the truth?" Sherlock Holmes

Click to expand...

William of Ockham (1285-1349) English theologian and philosopher
Ockham's razor (also spelled Occam's razor, pronounced AHK-uhmz RAY-zuhr) is the idea that, in trying to understand something, getting unnecessary information out of the way is the fastest way to the truth or to the best explanation.

"If you have two theories that both explain the observed facts, then you should use the simplest until more evidence comes along"

"The simplest explanation for some phenomenon is more likely to be accurate than more complicated explanations."

"If you have two equally likely solutions to a problem, choose the simplest."

"The explanation requiring the fewest assumptions is most likely to be correct."



That's our homework asignment for the weekend!

It is not a given that you have one issue that is causing both your problems. I once had a boat that had a frozen pin on the transom, i.e., the pin that the drive latches too and determines the angel of the prop. It was stuck in the closest hole to the tramsom and the boat had a pull to one side that I could never get the trim to compensate for.

RicardoMarine said:

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Click to expand...

Hi Rick,

Thanks again for helping work this mystery. Yep, if it were ONLY the bogging down and "apparent too high gears" then it would be a little easier. The pulling very hard to port makes the mystery deeper.
We started out Weds on the water with the little steering fin adjusted approx. 1/2" to port, where I'd always had it adjusted on the original outdrive. There's also an older set of "trim tabs"--the type with a movable plate adjusted by two bolts. I had them in the same position as before, never touched them on the initial run--they were adjusted in an almost neutral position. Perhaps each side was down maybe 1/8". I sit the outdrive on the middle position (of the three positions) for the reverse kick-up latch to lock on to. That is where the boat had always run well before.
So that is how we started our test run. First time trying to power up leaving the dock, I noticed the hard pull to port and when I got the motor up to running temp and tried coming onto plane, it just bogged down and keep pulling harder to port--as abundantly described already..:rolleyes:
Okay, to work through your last questions:

1) New anode ring in place and secure.
2) Same exact line cutter, spacer and prop as before.
3) Trim fin was a NEW VP replacement with the same adjustment--approx. 1/2" to port (or within a hair of the adjustment on the original) the boat ran straight and true previously with the adjustment.
4) Hinge pins were shiny clean, with a little marine grease and gently tapped in snug--absolutely no play in them. Also new black plastic bushings on both sides.
5) Main suspension fork is the same as before, original. No cracks, fractures or anything visible that I could see. Trust me, I've got an INTIMATE relationship with all these parts and pieces by now--after about a half-dozen installs and removals! :rolleyes:

During out sea trials, we pulled the boat out of the water several times, on the trailer. Adjust the fin and trim tabs backwards, forward and in-between, also set the pin on the last, aft (of three holes) position to see if it would get us on plane easier.
NONE of this stuff made any significant difference.
The motor and boat, as they were set up before, with the original outdrive, ran this boat very nicely and she handled sweet, straight and nimble
One final variable. There was a set of "Doel-Fins" (or similar) bolted on the "old" outdrive. We left them off the rebuilt unit. That shouldn't have caused either of these problems.

At this point, I don't know if there's one problem (gearing?) causing the two major symptoms OR if it's a combination of things.

Here's my PLAN B. I'm trying to buy a good used early 80's 270 that was matched to an AQ125a (I ran late 70's 280's before) from a guy locally for a few hundred $$. If I get it this weekend, I'll install it by Monday and run the boat. IF she runs fine with a replacement outdrive, then we've eliminated everything except the "rebuilt" outdrive. A lot of work, but I'm determined to figure this thing out.

UPDATE:

Got a call from the rebuilder. He felt sure that the gears, etc. are correct--he's being very decent about the whole thing and just wants to find a solution. He suggested the stabilizer fins that were bolted on the original outdrive.

The ONE big item that's different is the fact that the original outdrive had a Doel-Fin installed by the previous owner. On the rebuild, I left them off. Didn't figure it made much difference.

SO....we're thinking maybe put the original lower housing (that has the Doel-Fin mounting holes already drilled in it) back together, assemble the entire outdrive THEN attach the Doel-Fin again that see if that solves the problem.

The boat may have some "quirkiness" to the hull (Just like a few boat owners have some quirkiness :rolleyes. That may be why the previous owner installed the Doel-Fin. Maybe, maybe??

The "fin" would create more lift for getting on plane. By NOT being there, it COULD (possibly, maybe?) cause a hard pull to port. The resultant drag (maybe, might) be why it's acting like the gears are wrong or seeming like it's way over-propped.
Inductive and deductive reasoning? It's the best course of action so far that we can come up with. Makes more sense that any of the other stuff. I think I may hold off on installing a used 270 for a test and most likely pursue this path.

It's warm and sunny here in the Pacific N.W. and I'm taking my Harley for a ride to refresh my brain!

WAY, WAY back, I had a customer's boat, believe it to be a Bahama Tri-hull, that would pull so dang hard one way the trim fin did nothing. This was a 270 and end the end it would not work with a right hand prop. It had to be a left or the pull came right back. Just remembered this.

Hi Gary,

Good point. I had considered that. That said, this boat has been running fine for the last 7-8 years with R-hand props up until I changed out the outdrive and left the Doel-Fin off.

It may be a combination of things adding up to create the problems previously mentioned.

1) I think if we go back to the original lower gear case or straighten the skeg in the current one,
2) Re-attach the Doel-Fin as it was before.
3) And adjust the steering fin and trim tabs exactly back as they were prior to the outdrive swap...then....

The combo Should, Maybe, MIGHT solve the problem. It may be that the extra lift caused by the Doel-Fin raises the stern or straightens it out enough to counteract some quirk in the hull. (Where's a good physicist when you need one?)

Darned if I know, but it's about the only thing that makes sense at this point. The hard pull to port (Without the stabilizer fin and perhaps the small bend to the left on the rebuild's skeg) may just be too much for a 4 banger to overcome and causes it to lose those 1,000 rpms + or -.

We'll know after we make the changes.

RicardoMarine said:

William of Ockham (1285-1349) English theologian and philosopher
Ockham's razor (also spelled Occam's razor, pronounced AHK-uhmz RAY-zuhr) is the idea that, in trying to understand something, getting unnecessary information out of the way is the fastest way to the truth or to the best explanation.

"If you have two theories that both explain the observed facts, then you should use the simplest until more evidence comes along"

"The simplest explanation for some phenomenon is more likely to be accurate than more complicated explanations."

"If you have two equally likely solutions to a problem, choose the simplest."

"The explanation requiring the fewest assumptions is most likely to be correct."



That's our homework asignment for the weekend!

Click to expand...

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Rick,

I forgot to reply to this post. Yep, excellent points concerning "Ockham's Razor". Straightening the slight "left" bend in the "rebuild's" skeg (or changing back to the original lower housing) AND re-installing the Doel-Fin seems to be the "simplest" theory/solution.

Yes Teacher--This weekend's homework assignment has been getting worked on.

Maybe this situation is a little like having a small, pea-sized pebble in your shoe. The pebble is not much when considered by itself, but the "little" thing becomes a major problem when one is trying to walk, jog or run normally.
Folks could blame the shoes, uneven terrain, the foot, the person connected to it, a lump in the sock--OR just remove the pebble! "...Choose the simplest."

We're re-assembling the sterndrive tomorrow, will double, and triple check the overall gear ration. Will straighten the skeg just a tad, and then I'll re-installed everything on the boat. THEN re-install the "Doel-Fin" as it was for the last 8 years or so on the original outdrive.

Should have all of this done by mid-day Weds. Then out for sea trials late Weds or sometime on Thursday. If this doesn't work--I'm about out of options. I'm optimistic however, that I'll have a good report to this "mystery problem" by late Thursday.

UPDATE:
Finally got everything back together and re-installed the original "Doel-Fins". Re-checked the gear ratio AGAIN before install-kept getting 2.15:1 just as it should be. Also added Delo 400 15w40 instead of my usual straight 30 wt.. The outdrive seems to like it. Smooth forward/reverse and quiet operation--absolutely no slipping of the cone clutch noted.

After running around Northern Puget Sound a few times and coming in for some changes and re-testing, this what I found. The rebuilt sterndrive is not the problem. Re-installing the Doel-Fins made a noticeable difference. First run, the boat still pulled moderately hard to port, but only about 1/3 the force as before. The engine also bogged down when I opened the throttle, but only about 1/2 as bad as before. Again, like it needed a smaller prop. (Actually I'm running a 14x17 HS Right hand prop). I took it slow and steady and she would finally get going.
After adjusting the little "steering fin" more to port (About 3/4" total?) we actually got her to run STRAIGHT! Hands off the wheel straight--YEE HAH!. That was a major step forward.

THE BIG FACTOR seemed to be re-installing the "Doel-Fin". I'm sure this ol' '79 Campion hull has some quirks that are mostly corrected by the stabilizer fins. Next we adjusted the old style manual trim fins. Started the sea-trial in the upper most position and ended with both of them approx. 5/8" down equally on each side. I can now get on plane with a passenger in approx. 15 seconds (coming up at around 3200 rpms). I'd like to half that--but I understand the balance between "hole shot" and top speed and the longer run.
My top end increased from a really strained 4,000 rpms before, to an easier 4,250 + or - a few turns (But couldn't get any more than that). High speed (At 4,000 + rpms) turns-- port and starboard were quite stable with the Doel-Fin added. We were running in about 2' seas this afternoon.

I'm going to try picking up a 14x15 HS prop tomorrow to replace the 14x17 HS. That'll get me up a little quicker and get me closer to W.O.T. rpms.
Also running about 3/4's of a tank of last fall's gas. Even with stabilizer, that may be a small part of the equation. It doesn't miss a beat when cruising but maybe I'm loosing a little "umphh" overall?
Since I re-worked my shifter/throttle control, I may has lost a little top end via the throttle linkage. So tomorrow I'll pull the air cleaner, get the flashlight out and make darn sure I'm getting that throttle plate standing straight up when the throttle control is all the way forward.
Fine tuning now to work the kinks out and get her right.

Also found corroded and stripped threads on (one side) of the steering helmet when I did this last install this morning (They were holding up till now, but one let loose today when I was tightening it). Drilled and did the Heli-Coil route. Better than new now. You don't want one or two of the bolts on that steering helmet letting go while you're 20 miles out from the boat ramp! Good thing I found the problem.

All in all, with the changes and adjustment, etc.. I'd say the boat is running much better that last Weds. trip. I don't feel like sinking it now!
That's the report I promised. I may come back next week after a few more changes.

The learning never stops!

Good deal. Thanks for letting us know.

boatdoc55 said:

Good deal. Thanks for letting us know.

Click to expand...

Gary and Rick,

This morning I went to the Prop Shop and swapped my near new 14x17 R-hand prop for a 14x15 LEFT hand prop. (Just because something worked well last year and with another set up, doesn't mean it will work the same this year with a different set-up.)

1) Installed the new prop and moved the little trim/steering fin to the straight forward (neutral) position.
2) Added 10 gallons of FRESH gas to the tank
3) And pulled the air cleaner.

Took it out for another test. WHAT A DIFFERENCE.
Last week this problem seemed like it might simply be the wrong gears in the sterndrive, but it was a combination of misc. factors.

With all the changes, she now gets on plane in 7-8 seconds with two people. She just "felt right" coming away from the dock with the left-hand prop and the other things that were done.

She will get up to 4900 rpms on plane now. About as close to perfect for this little 2.1 liter 4 banger as one can expect. I still get a slight pull to port but a small adjustment on the steering fin will fix that.

CASE CLOSED as far as I'm concerned. The guy who rebuilt the sterndrive was patient and helpful through the whole process. He was happy to hear the results of this latest test run. By the way, the oil is now clean with no hit of gray or metallic dust. We figured the cases weren't cleaned out properly after media blasting. A change of oil after the last tear down inspection cleaned things up nicely. The sterndrive is quiet and shifts smoothly forward and reverse as long as I idle down under 1000 rpms and take a second or two between forward/reverse.
THANKS so much for the help I received here. Never had a problem like this one and it was just baffling until we sorted it out piece by piece.
I'll try to give some back when I have something to offer.

Some boats just don't like a particular prop and react just fine with another. I'm glad it all worked out and you can enjoy the most fun one can have in the upright position.

Yep, you're right about that. And...all's well that ends well.