1976 351w running very rough after top end reassemble - aaargh!!

Here is a typical graph showing resistance versus ohm for a water temp MARINE sender

So for the sake of argument, if you are running at ~130 degrees then the resistance will be ~ 130 ohms. The resistance lower as the temp increases.

So at ~ 160 degrees the ohms should be ~100 ohms +/-

kghost said:

A temp SENSOR/SENDER is a variable resister. ~ 120 ohms to ~ 320 ohms. Could be more or less based on sender design.

A temperature switch is a switch. When it reaches a designed set point it will close and short to ground and cause the alarm if such an alarm is present and is typically under dash but also typically on 1990 ish and newer boats.

Your boat and most in the 70's had no such alarms.

so I have no idea what the second is. One will read ohms and change with heat/cold. the other will show an open and when a certain temperature is reached will read closed.

Your engine should have two senders. Oil and temperature only

It is very very common that the SLAVE solenoid to fail This is a second stand alone solenoid (if your starter has on mounted to it). The typical symptom is it only clicks when key is turned.

Click to expand...

Looking closer at the manual there is mention of a temperature switch and alarm but it appears to be on the Inboard motors mostly. It is Not shown on the I/O's.


There was also a oil pressure switch and transmission fluid temperature switch.

Here is the schematic of it.

FstaRockr Burns said:

Well got everything up and running - have no clue, only thing i changed was plugs and confirmed the firing order was indeed stock. Anyways glad to be back up and running - motor is super smooth and power is back. Will set dwell etc now ..

Also i noticed there are 2 stats in my intake manifold - was this stock? Im thinking of wiring up a higher temp stat and using that as an alarm if its not stock..


Just a quick check - is this the correct position for the stat? Had some heating issues so killed it before it got hot - anyway, changing the rear impeller now too. I presume the lower water pump pumps water up into the motor? only have muffs too - maybe ill fill a tank and try that rather..

View attachment 15037

thanks

Click to expand...

Suggestion:
Simplify your outdated raw water cooling system by eliminating that housing and the unnecessary plumbing.
Find and use OMC 5.8L Ford housings.

RicardoMarine said:

Your plumbing would now change to this tried and proven and more modern configuration:

Click to expand...

Seeing as Mercruiser alpha I/O based impeller design has been around since at least the 1960's..........

I would say it is tried and proven.................

1) re: "Also i noticed there are 2 stats in my intake manifold - was this stock? Im thinking of wiring up a higher temp stat and using that as an alarm if its not stock.."
"Stats" control water temperature
"Sensors/senders" feed the temp gauge
---and---
temp switches are switches that feed... alarms
Sensors and temp switches usually fit in the same size tapped hole external to the engine block itself, "stats" never do.

2) In all this discourse I didn't see if this engine was run in fresh water or in sea water. When I bought my current 1969 Chris in 2005 it had its original raw water and hence sea water cooled 283FLV engine. It ran like a clock. The PO had fresh water flushed it every time he used the boat. I replaced the engine after one season as I'd seen more than one raw water cooled engine running in sea water that ran fine, did not overheat, but had a chunk of the sidewall of the block fall out without warning while the engine was running. Superficially, the block was fine, it rotted out from the inside.

sheesh - well thanks.. had her out and the shifting was awful - never calibrated the shift interrupt switch.. also ran out of gas 50 yards from launch (fuel gauge was mucking about) but sorted that out. Was under the impression we had half a tank - as usual lucky I had a few gallons spare and rigged something to get us back.

Ill look at the pics - so far the temps are staying very nicely at about 30% of the green stable.. max I reached was 50% on the muffs at high idle. Boat runs quite powerful - just SUPER hard to steer when running (fine out the water), this is before there is even enough speed for trim tab to have much effect.

Ill be monitoring the sensors closely.. fyi i coated the manifolds and elbows with corroseal, incl all water pumps / fittings etc. Id love to do the block but that would require almost 2 gallons of the stuff - maybe oneday..

Well - hopefully I can sort out the last few niggles and get the boat running sweet... about time

And yes I flush each and every time with fresh water for about 5-10 mins - hose down trailer, etc etc. Its an upbringing thing imo.

Hard steering in a boat that old id simply the steering cable.

~ $140 to replace entire cable with helm kit

I think I posted instructions for the shift cable in one of you other posts but if you need it again let me know.

Do you have a no feedback helm? I just installed one last year and they are a bit stiffer does the wheel turn by itself when you let your hand off it? Glad your getting the bugs worked out sounds like your about ready to upgrade the guages and senders so you have safe trouble free outings. Good input from the guages will let you know when to get off the water!

To clarify: re".... chunk of side wall fall out..." Those engines were not flushed after use.

Hydraulic steering is the only way to fly!

o2batsea said:

Hydraulic steering is the only way to fly!

Click to expand...

I'll second that!


.

hi kg - yeah still have the instructions thanks, I think I got it sorted but the shift interrupt was def not working. Ill shout if im stuck -

Not sure what this canister thing is? There are 2 hoses that will screw onto this, not sure what it does, looks almost like a steering ram / assist or something?




Ill be removing the steering cable today to see if its binding while disconnected - and maybe lube it up and order something next week.


kghost - fyi, I used this method from my outboard (similar) for a fast setup: (just figured it myself)

Disconnect the helm steering cable from the engine bracket with helm ctrl in Neutral / locked position - Disconnect Battery(!)
** The lower cable has to be connected and assembled correctly of course / shoe / lower unit spline etc)
** The lower cable is never removed or disconnected, only the end eye from the helm cable is removed from engine bracket.

Now:
1: Have someone rotate prop backwards / counter clockwise (looking from behind motor)
2: Slowly push bracket/lower cable in towards Fwd position till the gears start to click/contact each other, make a mark on the lower cable sleeve
3: Rotate prop clockwise (looking from behind motor) and pull bracket/lower cable (towards Rev position) till it starts clicking - again make a 2nd mark on the same sleeve.
4: Between these 2 marks is the exact neutral mark on motor
5: Adjust the bracket till the lower cable sleeve is in the middle of these 2 marks
6: Lastly adjust helm cable barrel without moving the bracket / lower position and bolt in place.

Using the bracket gives a bit more leverage and makes it easier to get to the contact point of the gears -

The helm control is now perfectly adjusted to the neutral position on the cable/motor considering all variables of wear in helm AND joints / cables / etc..

Assuming your cables are not toast of course - this will get you perfectly in the center of the shifting margin for Fwd and Rev.

Works fine - just have to sort out the shift interrupt - hopefully back on the water today


Not sure what to do about steering - will report back today as well.

that is not the procedure I gave you but if it works then it works.

The alpha based shifting adjustments are geared towards having the control shifter in full forward wide open throttle when starting the adjustment.

The micro switch that is used for the interrupt is no longer available, Good luck finding a cheap replacement. Hard to come by for less than $60.00


I myself have some slightly different micro switches and they require different mounting holes to be drilled and tapped but work very well and saves the cost of a complete new shift bracket to get the currently available switch. They want you to upgrade to the new one and it cost ~$200 +/-

Typically the steering cable inner core wears into the outer core over time at the 90 degree bends at the helm and transom where the cable makes its turns.

If lubing it does not work which in most cases it does not you need to replace it...

FstaRockr Burns said:

kghost - fyi, I used this method from my outboard (similar) for a fast setup: (just figured it myself)

l.

Click to expand...

I also wanted to include, The set up method for an outboard is not the same as an I/O

The mechanics and linkage and the actual shift mechanisms and components and the geometry are not the same.

Maybe finding neutral but the rest is not guaranteed.

Mercs I/o's work off of forward/reverse gear engagement and how it interacts with the interrupter switch. Also how the engagement of for/rev gear interact with the control box so when shifted into gear and you advance the throttle you don't continue to move the short shift cable. This will engage the interrupter switch when it should not be (going into gear or advancing the throttle once in gear)

The short shift cable set up is the most important of all. If you did not adjust that and it works you simply lucked out!!



One would think the set procedures for each would then be the same but they are not. Wonder why that is?????????

The short cable has specific requirements which an out board does not have at all.

The short cable contrary to what you wrote and if replaced requires it to be set up a specific way therefor it is removed from the shift bracket.



I am not sure why to continue to BUCK the advice given here and try other methods which you have NO experience with.

Do you not think I know what I am saying?

I have personally adjusted/replaced well over 1000 short shift cables...............I know what and how they work!

yeah I was just sharing a quick an dirty attempt to get it working.. Switch was not wired up and it was not engaging - the steering moves freely out the water, so im assuming its ok -

Ill go thru the procedure u sent this weekend to the t - seems like the prop needs back pressure for the switch to activate since its connected to the lower cable far as i can tell.

Anyway - switch still works - I just have to make a longer wire to coil - to connect it to and see if it works. Might have to drop the lower unit - reverse is not engaging so nicely as before.. and i think the washer that sits above the gear spline shaft was not there when i pulled it - anyways.. hoping to be up and running very soon.

thanks for the info - have another poke next few days..

The interrupter switch originally was wired to a terminal block (two terminal) and one lead goes to ground and the other to the - side of the coil.

so the switch would connect to the terminal block and there would be two wires connected, - from coil and one wire from switch together.

The ground side of the terminal block was screwed into ground where it was mounted and the other wire from the interrupter switch was mounted there. If that is missing then one lead of switch goes to ground and other goes to - of coil.

As far as your steering, One aspect of I/O's especially older ones is when under power they want to steer to one direction because of the natural tendencies of the outdrive torque if you will, This was moderated by a power steering assist assembly mounted on the inner transom assembly and the end of the steering cable was connected to it which helped out a lot. The power steering pump (typically a standard GM automotive PS pump) would supply the power assist with the fluid and the steering should be like butter.

The newest power assists have far superior valving and the steering stays where you leave it for the most part.

On the older models there is or should be a "trim tab" hanging off the cavitation plate. This is also referred to as a Zink Anode.
This tab has rotational adjustment and can counter the torque I spoke to earlier.

Typically if the boat wants to turn left you turn it to the left (rotationally) I have mine set so that at ~ 2800-3200 rpm cruising I dont have to touch my steering wheel. Boat tracks perfectly straight.


Now in one of your pics you showed a small what looked like a hydraulic cylinder. it had two NPT fittings. I forget what this was used for back in 1977...
I will review my manuals to see if it is shown.

Do you have a power steering pump mounted on the front of the engine and driven by a pulley?

If so thats good. If not that is bad!! very bad and will dramatically affect the steering!! It will want to steer the way it wants and you will have to fight it all the time to keep the boat going straight

Now take a better picture of the inside transom area showing all the steering linkage where the cable is mounted.

trim tab............

Back in the day when the dinosaurs roamed the earth and merc was in its infancy they used a "hydraulic" trim sender.

This is what you asked about in the picture you posted.

Not sure but most likely they converted to the plastic pucks used on the outdrive as all current models use.

gr8 info jack - super busy working today/2moro but will have a stab this weekend.

many thanks!


No power steering at all! I looked this up 2 days ago - it doesnt really steer muchleft or right as uch as its VERY hard to steer period, out of the water the steering is very smooth and easy so i presume my cable is ok -

So what options do I have - I do have a 2 belt pulley on crank.. adding a PS to the front wouldnt be hard at all.. linking it up is where i wouldnt know where to go - could I fit a bolt in ps unit from another year?

like this?

Rule of thumb is

you should be able to turn the steering wheel with one to two fingers with little or no real effort. The only effort felt should be the weight of the out drive if you can picture/understand what I am describing. You can disconnect the outdrive steering arm from the cable and see if there is any difference. If no difference and the cable is still tight as I describe below then the cable is bad.

if you have to grip the wheel with you hand somewhat tightly and sort of tug on the steering wheel and you have no power assist as you show in the picture in you last post then the steering cable is bad.

Adding the power assist may be beneficial but not sure its worth the cost of all the parts unless you find a donor boat. Any system from any Mercruiser what ever the size engine will work. Not sure your transom assembly has the mounting locations built into it....been a LOOOOOONG time since I worked on a boat that old.

Hi - got boat out on the water today.. motor ran good! temps stayed well below 50%, out for about an hour. bit choppy to open her up - and the boat was biting left and right when i picked up some speed (gimbal joints or trim rubbers).

Anyway - 17pitch prop was doing about 19mph at 2400rpm - is the gear ration really a 1.32 in this thing?

Got shifting working - rev still a bit sticky but wired up the neutral interrupt switch and she gets in and out so much easier now i actually rode boat up onto trailer - lol. with a sticking fwd that was previously not an option.

Look at the gimbal ring. the ring should not have any slop in it where the steering pin is clamped. Hard to explain but if you grab the drive, drive should move left and right and ONLY move the steering cable with it.
If the drive moves say 1/4 inch to the left past center and also 1/4 to the right past center for a total of 1/2 inch of total left to right movement before the cable moves, look at the center top of the gimbal ring where the vertical steering pin is "crimped/clamped" with two shoulder bolts. You can try to tighten the bolts but they only tighten so much (shoulder bolts).

If the clamp area has too much slop in it that may be your problem.
If it is your issue you will need a new gimbal ring and there is a merc kit available to access the steering lever nut which is behind the top part of the transom housing.

Kind of a big job.........in some cases it easier to remove the engine and remove the transom assembly and rebuild on a bench and then reassemble the boat.

If that is your issue.

thanks ill have a look when i get to the boat again. Yeah, on 2 occasions she bit into the water.. quite scary - wasnt on speed, it was just too choppy but very unsettling! I have to adjust the trim tab too, right was super easy and left very hard - have fuel gauge to troubleshoot, trim level gauge and side trim flaps -

Ill rent a torque wrench and do those shoulder bolts too - 55ft lbs?

kghost said:

Look at the gimbal ring. the ring should not have any slop in it where the steering pin is clamped. Hard to explain but if you grab the drive, drive should move left and right and ONLY move the steering cable with it.
If the drive moves say 1/4 inch to the left past center and also 1/4 to the right past center for a total of 1/2 inch of total left to right movement before the cable moves, look at the center top of the gimbal ring where the vertical steering pin is "crimped/clamped" with two shoulder bolts. You can try to tighten the bolts but they only tighten so much (shoulder bolts).

Click to expand...

Hi-had a quick look today, I have about 1" sideways movement TOTAL on the tail. Where are the should bolts? Do I need to remove the outdrive (like replacing lower shift cable) to access these?

Rented a torque wrench -

From steering wheel I strapped the outdrive to one side and tightened it up - steering shaft behind motor moved about 3/8 of an inch - I think the steering arm going backwards toward motor (where the square joint sits) was moving in/out a little bit - the help steering also showed about 1-2" of play before the rear cable started moving -

all in all i think the whole steering system is just plain sloppy! but form what ive seen the rear end doesnt move as much as some of the vids ive seen - i think an inch is ok?

Ill check the gimbal ring this week to see how much it moves - also up and down i had about 1/2" or less of movement on the whale tail end - seems ok?

I am telling you straight up!

The outdrive should not move more than 1/2 total left to right before steering cable moves. And that is for an old boat. New ones don't even move that much.

If you were to bring this boat to a marine repair shop and they found this issue while doing other repairs they would not give you back your boat until you had the steering system restored normal function.

Having that kind of slop is very dangerous.

If you are seeing 2 inches then find where the slop is and decide your next action. This may not be a easy or inexpensive repair as I noted above...

FYI

This is what happens when you try to resurrect an almost 40 year old boat that was not properly maintained.

Here is a link to a youtube video

If you look closely at where the gimbal ring and the VERTICAL steering pin mate up. When they move the dive left to right the VERTICAL pin does NOT move.

This is the slop I am referring to.

It is a bit difficult to see but watch closely.

Yours is older and your vertical pin may not be exactly the same but the same condition could exist.

https://www.youtube.com/watch?v=epqhFpEZ9ys

kghost said:

I am telling you straight up!

The outdrive should not move more than 1/2 total left to right before steering cable moves. And that is for an old boat. New ones don't even move that much.

If you were to bring this boat to a marine repair shop and they found this issue while doing other repairs they would not give you back your boat until you had the steering system restored normal function.

Having that kind of slop is very dangerous.

If you are seeing 2 inches then find where the slop is and decide your next action. This may not be a easy or inexpensive repair as I noted above...

FYI

This is what happens when you try to resurrect an almost 40 year old boat that was not properly maintained.

Click to expand...

2 times on this one.

I have condemned boats for this same reason.

With an inch of movement.....Your gimbal ring is probably wiped out.

There is no fixing this, The price of a new complete unit is not expensive....I would replace it as a whole with a gen2 housing and get a new drive.


Or, like I said in one of your many threads....Find a newer donor boat that has a good power package.

fyi far as i can tell the rear end moves an inch total, not either side. thats with the steering wheel being held tight and me moving the whale tail side to side and measuring the distance.

Anyways thanks, ill look at replacing the parts - i do want this boat working well..