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Honda 50A locked up and need input!

M

mitchbuck

Contributing Member
Hi all, great forum here and here's my first post. I have done some searches here and they have been helpful but I'm looking for more info. Anyways, I have a SeaCat 21ft CC with twin 2002 Honda 50-hp outboards (carb'd) and both engines had work done over the winter (carbs, head gaskets) by a certified honda mechanic. The starboard engine has developed some problems recently and I need some help it diagnosing the latest issue. First the engine developed an oil leak from the crankshaft seal on top of the powerhead (underneath fly wheel), which was replaced by the mechanic. It ran well for 2 trips and then the engine quit on me over the weekend at the ramp. It started up fine but then shut off suddenly. The voltage on the gauge dropped very low so I tried jumping the engine thinking the battery was toast. The engine ran for a little bit after being jumped but then started making a ticking noise before shutting off. This week I did some trouble shooting, and I thought I had an electrical problem so first I swapped a new battery in but the engine wouldn't turn over. The starter gear would engage the fly wheel but it couldn't turn it. Anyways, I wasn't sure if it was a bad starter, but I suspected that the fly wheel might be stuck (after readying some threads on here). So I got out a pull cord and tried turning the fly wheel manually but it wouldn't budge. I checked the other engine and I could pull the fly wheel fairly easily.

Anyways, it seems that the fly wheel might be getting stuck, and I'm trying to figure out why. I thought initially that I had electrical problems due to a bad rectifier or stator, and I read a thread on here regarding a bad rectifier where one of the members mentioned that the coils can delaminate and impinge on the fly wheel locking it up. I noticed a couple metal shavings so it could be that but I'm not sure if its from that or leftover from the oil seal replacement. I can rotate the fly wheel back slightly so it's not completely stuck. My other fear is that because these are interference engines that maybe the timing slipped and the valves are hitting the pistons. I checked the belt tensions and the its a little looser on this engine than the good (port) engine, but not sure if it would be enough to make a difference. Its hard to say whether the timing marks between pulser and fly wheel are lined up correctly but there seems to be a small difference between each engine....not sure if its real or not at this point.

So I'm looking for input on what diagnostics I should perform next.
1) I have a spare starter that I can swap in, but not sure if it will matter since I cannot pull the fly wheel with the rope. Is it worth trying to jump the engine again or is that too risky?
2) Should I just go ahead and pop the fly wheel and if so are there any special tools that I need? Such as something to hold the fly wheel steady such as a simple strap wrench? I actually have a parts engine with a fly wheel and stator coils.
3) Is there anything I can do to check timing or if valves are hitting pistons? Maybe scope the spark plug holes?

Any other input is appreciated!
 
First of all....do not put another starter until you can rotate the flywheel by hand.

If there seems to be a sound coming from under the flywheel when you reach a stop in rotation, pop the flywheel and see if anything is locking it up under it. Easiest way is to use an impact gun to loosen the bolts. Loosen in crisscross pattern. Then just lift the flywheel off. The magnets have strong holding power, and you may have to use a couple of screwdrivers to help you lift it off. There is no keyway, but there is a locator pin, when you put it back on. Do not the impact putting it back on.....torque it properly....criss cross pattern....47.7 ft lb.

If all ok up top....take out the spark plugs and make sure there is not metal on any of them.

You can not check the timing yet....until you can rotate the flywheel.

Then take off the lower unit. It is possible that it is locked up....thus stopping the lower unit from rotating.

Once you get the flywheel rotating, then you can check the timing marks on the cam and the flywheel to be sure that timing is correct.

Mike
 
Thank you Mike for your prompt reply! I'm getting my hands on an impact gun this weekend. Do I need a strap wrench or special tool to hold the fly wheel steady while I remove the bolts? The prop spins freely so hopefully the lower unit isn't locked up.
 
Since the flywheel turns counterclockwise...if you hit the bolts in short spurts, you shound not need to hold it. Keep the spark plugs in for this.

You will need some sort of holder when you put it back on.

Mike
 
Update from the weekend. So first I popped the spark plugs to remove compression and the engine was still locked up. Then I popped the flywheel and after inspection it doesn't appear that the fly wheel magnets are hitting the coils as shown in the photos.
Coil1.jpg
Flywheel.jpg
To confirm this, I removed all 3 coils and lightly installed the fly wheel and the engine is still locked up! Based on Mike's suggestion I dropped the lower unit as I needed to change the impeller anyways. The shift linkage nut was not seated against the lock nut which I found curious. Anyways, after changing the impeller and reinstalling the lower unit and shift linkages, the engine is still locked up!

So I inspected the engine further with the fly wheel off and noticed that the timing belt tensioner was not installed properly!!! As you can see the flange is off the guide post. That explains the timing belt being looser on this engine than the port engine. Could this somehow have lead to the engine locking up say if the timing slipped or something else? I tried loosening the bolt to fix this put it was on there too tight. I will likely have to hit it with the impact gun.
tensioner.jpg
 
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I am also going to scope the cylinders through the spark plug holes to see if I can see any sort of obstruction or the valves hitting pistons...
 
mitchbuck said:
I am also going to scope the cylinders through the spark plug holes to see if I can see any sort of obstruction or the valves hitting pistons...
Click to expand...

Scoped it and couldn't see anything obvious. I'm kinda out of ideas at this point. I don't think the misplaced tensioner is causing this so the only thing that I can think of is a bent valve(s)?
 
Just two questions

Did you check the engine lock up while the lower unit was off? You didn't really say.

Do all the timing marks line up.?

Mike
 
Sorry, yes after I had the lower removed completely the engine was still locked up!

I can't return the timing mark on pulser rotor to TDC because its locked, but when I line up the marks on the good engine with those of the locked engine, they both appear to match close. Also, the arrow on the pulse rotor is pointed at the correct mark on the timing belt, so I don't think it slipped.
 
Sounds like you have eliminated everything external.

Time to at least pull off the valve cover and see if there is anything obvious there.

If not, then it is pull the head time.....not hard to do....and will come off in one piece.

Sorry that nothing obviously simply showed up.

If the timing was correct.....something must have just let go internally.

Mike
 
I have no experience here but would it not be worth removing the timing belt and seeing if you can get movement from the block or head independently? Not so much that you force valve & piston contact but enough to point out which end is not rotating before you strip the motor down? Again I must state I have never done this. There maybe dangers I have not foreseen involved.
 
Thanks Mike I appreciate your input and that's what I was worried about. I actually watched my mechanic take the head off this motor last fall in short time so I'm pretty confident I can start with the valve cover with minimal effort and go from there. I think my biggest concern is replacing the timing belt if I need to tear the head off...although I did this on a old Mercury Force 2stroke a while back so I do have some prior experience.

Deanmck - That's a good point. If I need to remove the head I will start with timing belt and then check each rotor independently to see if they can move past that point where its getting stuck.

Looks like I got another weekend project in front of me...
 
One more question. I have the SELOC manual but don't have the Clymer or shop manual. Between this forum and youtube and SELOC do I have what I need to disassemble/reassemble valve cover, head, and properly reset timing belt? Or should I pick up one of those...
 
If I was in your position I would get the proper Honda manual. I have heard & read here that other manuals are not up to the job once it comes down to the nitty gritty work. In the end I think Honda knows Honda best.
just my point of view.
 
So the mechanic has agreed to take the boat back and correct his error. Hopefully the tensioner and belt just needs to be reset and the valves aren't bent. In the meantime, I've been trying to address the low voltage electrical issue using a quality multimeter from my office to test the various electrical components. Most of my numbers didn't match anything in the SELOC manual, but I compared the resistance on the various electrical components with those on a parts engine I have and this is what I found:

The Charge Coil was 0.3 - 0.4 Ohm on both the engine and parts engine. I know the Manual says <0.2 but as the accuracy of this measurement by the multimeter since its so small.
The Exciter Coil was ~190 on the both the engine and parts engine, which seems to check out against eachother.
The Pulser coil was 310 & 621 on the engine and 309 & 622 on parts engine, which checks out against eachother.
The Rectifier was 655 KOhm +/- 4 KOhm on all leads on both the engine and parts engine except for one lead on the problem engine which was 629 KOhm. So this is the only thing I found where there was an obvious discrepancy between the engine with the electrical problem and the parts engine. I'm just not sure if a 26 KOhm difference is enough to isolate the rectifier as the problem especially when these numbers don't even match what's in the book?
Hopefully my buddy who is an electrical engineer comes down this weekend to help me out with this.....I'd like to isolate the electrical problem so the mechanic doesn't have to deal with it (I feel like most mechanics aren't good with this stuff they just replace parts till it works).
 
Without the engine running, resistance checks only tell you part of the story. It is so much better and quicker with the motor running.

Remember, this motor will run all day without a charging system..

It is good that the mechanic is stepping up.....you most likely have some bent valve stems if the timing belt slipped while running.

Mike
 
Thanks Mike! I'm aware the resistance tests are only so good but without the engine in operable condition its about all I can do. I wasn't aware that the engine could run without a charge system and that's great info to know! I guess that would likely mean that either the rectifier or CDI is the problem. It looks like that you can't just order the valves (checking boats.net) so am I stuck buying a used head? I have a parts motor but the condition of the head/valves is fair at best (pitting on cylinder head walls).
 
So I just wanted to update this thread. I took the boat back to the mechanic and he found that one of the valve springs broke and put a valve through the piston head?!?!?! I have never heard of this happening, has anyone else? Valves are usually bend from my experience so this sounds a little odd. Anyways, I'm in the market for either another used Honda 50. Although I am also wondering if I shouldn't just look around for some used Honda 90s as my 21 SeaCat is underpowered with the 50s. Do the 90s from that same era (2002) have the same or different controls, gauges, and wiring harnesses?
 
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