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5.0 LX 1987 mercruiser starter problem

Docksidemarineservices said:
Wow.....
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''

WAIT WHAT???

the exhaust manifolds are 32 years old?
it matters because the water in the cylinders could most likely be coming from worn out manifolds/risers.

mainfolds and risers typically have a 5 year life span, maybe longer in fresh water.
i wish i had an old ring gear laying around but not at the moment.

does anyone else have thoughts on the flywheel issue?
 
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Gear Mesh.jpgLearning something new every day. Damn, have to change the manifolds and risers too. Still Do not know why. Don't they just have water jackets casted in them to separate exhaust from water and gaskate between them? Are you saying that cast iron wall between exhaust gas and water totally rusts out? I will check that and replace if needed.

Like to show you a picture of a good spur gear contact pattern and mine is just a mm or 2 shown in yellow. for hydo-lock, Pinion should just stop as it did a couple of times if contact pattern was correct. Sloppy design.
 
fsamie1 said:
View attachment 21665Learning something new every day. Damn, have to change the manifolds and risers too. Still Do not know why. Don't they just have water jackets casted in them to separate exhaust from water and gaskate between them? Are you saying that cast iron wall between exhaust gas and water totally rusts out? I will check that and replace if needed.

Like to show you a picture of a good spur gear contact pattern and mine is just a mm or 2 shown in yellow. for hydo-lock, Pinion should just stop as it did a couple of times if contact pattern was correct. Sloppy design.
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that photo is a constant contact gear to gear, your dealing with a bendis that is throughing a gear into another.
yes, the water jackets fail, the gaskets fail.
the water seaps into the exhaust manifold and goes in through the exhaust vaslve port allowing the chamber ot fill with water, or just enough water to cause hydrolock. water does not compress. most times the water causes the engine to stall, then when you try to restart it, the water not being capable of compressing, does 1 of these things, sometimes more:
bends the piston rod, bends valves and whipes out the sterter/flywheel teeth.
your not going to reengineer the starter system. install the starter, turn the flywhel to a clean tooth area and see if it starts.
run a compression test.
if you can get your hands on a boroscpope, $25.00 on amazon, go into the cylinder through the spark plug hole and see if the cylinder walls have rust on them.
report back
good luck
 
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chs said:
that photo is a constant contact gear to gear, your dealing with a bendis that is throughing a gear into another.

May I assume that you meant Bendix gear? If so, it is very unlikely that he has an old school Bendix style starter motor.
More than likely, he has a starter motor style the same or similar as to the one shown in my post #8.
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.
 
Well, had the starter modified so it is 2 mm closer to ring gear. Put it in and removed all spark plugs and to my surprise water came out of couple of cylinders. crank the engine and starter worked fine and no noise. Did cranking a few times and then put in WD40 in all cylinder and turn it again to lube cylinder walls. Now I have to after risers and manifold to find out where it is leaking into cylinders. It is probably the gasket since I cannot believe 1/4 inch of steel wall can be rusted through. If that is the case, we need to change cylinder block every few years too. Thanks for everyone's help.
 
I will say it... That was an amateur move.

The iron the block is made from is far superior to the crap they make the manifolds and elbows from.

Besides the fact that the temp of the water in the manifold can boil and that makes air bubbles. When Each bubble forms, it takes away a microscopic piece of iron.
 
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fsamie1 said:
Well, had the starter modified so it is 2 mm closer to ring gear.
I am curious as to this starter motor modification!
.....Bolt bores plugged and off-set re-drilled?
.....Bolt bores elongated?


Put it in and removed all spark plugs and to my surprise water came out of couple of cylinders. crank the engine and starter worked fine and no noise. Did cranking a few times and then put in WD40 in all cylinder and turn it again to lube cylinder walls. Now I have to after risers and manifold to find out where it is leaking into cylinders.
It is probably the gasket since I cannot believe 1/4 inch of steel wall can be rusted through.
The manifolds and Elbows are cast iron, not cast steel!
If Spacers/Risers are used, they will also be cast iron!

I don't recall who mentioned 1/4" material thickness. They were most likely referring to the approx 1/4" wall thickness between the seawater transfer ports and the main exhaust chamber.
Look at the areas with the orange arrows leading to them.
These areas become rust compromised, they loose the 1/4" wall thickness, the gasket will fail, and these areas will eventually leak seawater into the main chamber.
The engine's cylinders are not capable of compressing water......... hence a "Hydro-Locked" cylinder or two!


Exhaust manifold transfer ports explained.jpg





If that is the case, we need to change cylinder block every few years too.
See above.


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Also consider that when a GM SBC cylinder block casting is first set up for initial machining, indexing alignment bores and dowels are machined and installed.
Each and every consecutive machining processes uses these alignment areas as control points.
Crankshaft bearing bores, deck height surfaces, cylinders, cylinder head bolt pattern, camshaft bearing bores, oil pan surface, front and rear surfaces and bolt patterns, etc etc etc, including the starter motor mounting bolt pattern and precise location.

What I'm suggesting here is..... it's very unlikely and doubtful that GM screwed up on the initial machining and location of the female starter motor bolt threads that would cause the need to modify the starter motor nose housing bolt bores.

To do what you have done is a band-aid fix for an otherwise deeper problem!

.
 
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Being that you cleared the cylinders , put water into each manifold and see if it comes out the sparkplug holes. Then drain the manifolds and elbow , remove the elbow and inspect the bottom of the manifold for wetness. That is your bad manifold or elbow.
 
thumbnail.jpgthumb.jpgThanks Rick for discussing my issues. First thing, I do not like 1-2 tooth contact, no gear is designed like, obviously it works as long as there is no hydro lock. It will be sheared of with hydro lock due to inertia effect. It should just stop turning crank with no damage unless a different cylinder fires and bend the rod. BTW, I worked for GM for 35 years as an engineer. I think the block is bored correctly but merc and after market folks just did not do it right. Here is a picture of starter hole elongation that made it 2 mm closer to ring gear.

After work, removed the riser and picture of one is attached. they both look perfect, no rust thru as long as I can see with camera. I think changing manifold and riser every 5 years is total non-sense. Look at mine, they are 32 years old. Gaskets were both in pretty bad shape as that is my fault. I had to remove risers a couple o times but did not change the gaskets. I am going to take Bt Doctur advice and test them for leak anyway, It will cost me $30 worth of gasket to check them. Thanks Bt Doctur.

My big lesson was, if starter quit turning all the sudden, do not crank it any more. You will end up with chowed up flywheel or bent rod.
 
..." I had to remove risers a couple o times but did not change the gaskets."

Yikes! You're braver than me. Easy to get water in a cylinder that way.

Jeff
 
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fsamie1 said:
Thanks Rick for discussing my issues. First thing, I do not like 1-2 tooth contact, no gear is designed like,
No disagreement there!

obviously it works as long as there is no hydro lock. It will be sheared of with hydro lock due to inertia effect. It should just stop turning crank with no damage unless a different cylinder fires and bend the rod.

BTW, I worked for GM for 35 years as an engineer. I think the block is bored correctly
I don't think that any of us had a concern about the cylinders being bored correctly.
My comment pertained to the machining of all areas of the cylinder block... including the starter motor bolt threads!

but merc and after market folks just did not do it right.

Here is a picture of starter hole elongation that made it 2 mm closer to ring gear.
Being an engineer, you certainly know why the starter motor nose housing mounting bolt bores are to be a tolerance specific size.
The knurled areas of the bolts are to serve as alignment dowels.
When/if the nose housing bolt bores are enlarged, this dowel/alignment affect is removed from the equation.

Now the concerns will be:
.........will the starter motor torque now shift the alignment, even while the bolts are tight?
.........will the starter motor stay in place while undergoing the torque, even while the bolts are tight?
.........with the bores elongated, and if the starter motor nose housing was to shift, now it can shift even further than it could before!



After work, removed the riser and picture of one is attached.
I believe that you mean exhaust elbow. (see my image in post #38.)

they both look perfect, no rust thru as long as I can see with camera.
Agreed..... the transfer ports and the material between them and the main exhaust chamber look to be OK.

Suggestion:
*** take the exhaust components in to a machine shop for cleaning a magnafluxing. The magnafluxing process will find any cracks.
If need be, a machinist can true the mating surfaces by using a machine shop surface sander. It should take him no longer than 5 minutes per each surface!

I think changing manifold and riser every 5 years is total non-sense. Look at mine, they are 32 years old.
A 5 year interval is a general rule and/or suggestion.
But again, see *** above!

Gaskets were both in pretty bad shape as that is my fault. I had to remove Elbows a couple o times but did not change the gaskets.
Do as you wish...... however, all gaskets and/or O-rings are One-Time-Use items.
Never try to re-use them!
Gaskets will be compressed beyond re-use, and O-rings will have taken a "set" and will be beyond re-use!
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I have to question your back ground.

Merc did not cast the block, GM did.

Prediction.... The starter will now move and or snap the bolts.

Smack that elbow with a hammer and see if it stays together.
 
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Docksidemarineservices said:
I have to question your back ground.
No offense to the OP....but I would also question that!

Merc did not cast the block, GM did.

Prediction.... The starter will now move and or snap the bolts.
As noted in my previous post, I predict the same.
Had he over-drilled, pressed an aluminum bar into those bores, and then re-drilled the off-set bores, it may work!
Operative word "may"!

However, it would still be a temporary fix for an otherwise over-looked and perhaps ignored problem.

Smack that elbow with a hammer and see if it stays together.
No comment!
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Docksidemarineservices said:
I feel like the OP is trolling the site. This cannot be a real issue.
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what is OP?

I am sure you are following all procedure that Mercruiser manual tell you and I am speaking based on my observation and fact.

1. Eight mm long gear tooth should mesh more that 1-2 mm. I am sure block is drilled correctly but starter is not.

2. Exhaust manifold and elbow do not need to be replaced every 5 years. As I noted, mine is 32 years old and still good.
 
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fsamie1 said:
what is OP?
As said.... OP = Original Poster, of which in this thread would be you.

I am sure you are following all procedure that Mercruiser manual tell you and I am speaking based on my observation and fact.
I'm not aware of any OEM manual that addresses your exact issue regarding a starter motor bolt pattern boo boo.

1. Eight mm long gear tooth should mesh more that 1-2 mm. I am sure block is drilled correctly but starter is not.
I assume that you meant 8 mm "deep" pinion gear teeth.
And yes, the cylinder block is most likely drilled and threaded correctly.

2. Exhaust manifold and elbow do not need to be replaced every 5 years.
The 5 years is a recommendation for replacing Elbows, not necessarily a mandate.

As I noted, mine is 32 years old and still good.
If not caused be a cracked cylinder head or cylinder block, what then is a reasonable explanation for the water in your cylinders?
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Is someone wearing coat tails here?

Peat and repeat and repeat again.

The OP is an " engineer"

Enough said.

he has side stepped all advice until after the fact.
reworked elbows and manifolds and never changed haskets (exhaust and water) go figure...

35 years.....and that was doing what?

From the begining of this thread it was suggested to check for water in the cylinders.
You disregarded that advice because you know better because you have "35" years experience?

What do you think many who attemp to help have? And what do you think that experience is from? (With the expection of one)

I think this OP should rethink his approach, buy a NEW unmodified starter and fix the root problem and dont modify anything before solving the root problem first....

JMHO
 
So to put this in perspective the OP destroyed a perfectly good motor and starting system instead of simply replacing the ring gear. Not finding where and how the water got into the cylinders will surely destroy the new starter too. Either mechanical failure or failure on the person working on the motor to replace any gasket that was removed instead of reusing it.
Penny wise, dollar foolish
 
come on guys, do not need to be sarcastic. This is a great forum for trouble shooting and I appreciate all your help. As you all noted, my biggest mistake was not changing the gaskets after removing the riser. I changed flapper valves and I did not change it and another time looking for broken flapper valve and I did not change it. big mistake, I agree, water got to cylinders and tip of ring gear sheared off. Starter is fixed, I think. water is out of cylinders and all lubricated after putting oil thru spark plug holes. Got new gaskets and going to put it back together today.
Whole problem started with broken shutter valve and I thought it is blocking exhaust and limiting the engine to 2500 rpm under load. Appears low power issue was due to old plug wires, 32 years old and may be bad distributor, rotor, and ignition module. Got all new ones and going to change them today.
I am not as bad as you guys think. Worked at R&D center on transmission all these years starting from 3-speed and now 9-10 speed transmissions.
 
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fsamie1 said:
come on guys, do not need to be sarcastic.
I agree....... there's no need for sarcastic, nasty or rude ego based comments.

As you all noted, my biggest mistake was not changing the gaskets after removing the riser.
Elbow!

I agree, water got to cylinders and tip of ring gear sheared off. Starter is fixed, I think.
Well, as you've read, most of us agree in that you have NOT fixed the issue by modifying the starter motor nose housing bolt bores.
Your now elongated bolt bores are going to lead to the same issue..... and perhaps worse!
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Not sarcastic just being honest. You ask about a problem that "it does this" and we respond with our best guess depending on how you describe the problem. Our first answer was correct, water in the cylinders. For some reason you thought the starter was the problem, the ring gear IS the problem now. It will slowly but surely self destruct and you will be pulling the motor to replace it . Once the new ring gear is in place the modified starter will be useless and you will need a new starter or starter housing.
We can only point you in the right direction, it`s up to you to go in that direction
 
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