Hard clunk when trying to start

BOWTECH.JUSTICE

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Rebuilt 4.3 mercruiser just put in this summer. Ran great one day, the next day when I tried to start it I would get a loud clunk a couple times and then just a click when I turned the key. When taking the starter off I found that the threads are stripped on the positive post and on one of the smaller posts. Is a bad connection the cause of the clunking, and since the starter is only a year old, is it a good idea to solder the connectors on due to the stripped threads? The starter is an aftermarket model that I bought because of an issue last year and I didn't want to buy the more expensive one till I figured out why my last starter went bad.
 

Fishermark

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A hard clunk is never a good sign. First thing would be to see if the engine is seized up. See if you can turn the engine by hand. Remove the spark plugs if necessary - see if any are wet.
 

BOWTECH.JUSTICE

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Before taking the starter off, I took 1 spark plug out to relieve some compression so I could turn the engine over by hand as if maybe the flywheel had a bad spot (which it was fine). It was very hard to get the engine to turn but it's also very tough to do much work in there without removing the seat. That 1 plug was dry and looked good. Just how easy should an engine turn over by hand?
 

alldodge

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Before taking the starter off, I took 1 spark plug out to relieve some compression so I could turn the engine over by hand as if maybe the flywheel had a bad spot (which it was fine). It was very hard to get the engine to turn but it's also very tough to do much work in there without removing the seat. That 1 plug was dry and looked good. Just how easy should an engine turn over by hand?

Could be pretty hard to turn over by hand but do-able if you can get a big enough wrench on it. Now if any of the plugs have water in them, your not going to be able to do it even with a big wrench
 

Bondo

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A hard clunk is never a good sign. First thing would be to see if the engine is seized up. See if you can turn the engine by hand. Remove the spark plugs if necessary - see if any are wet.

Ayuh,..... I think I'd just start there,....
 

Bondo

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Took plugs out and yes there was water. Turned motor to flush water out. Now what?

Ayuh,.... Get it started, 'n Runnin',..... Then find how it got there, 'n fix it,.....

Does this motor have 1 piece exhaust manifolds by chance,..??
 

BOWTECH.JUSTICE

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I'm not sure what it would be other than 1 piece, so I am gonna say yes they are, with the elbows.
I am betting that I had a rush of water come up as I slowed to get a tuber.
 

BOWTECH.JUSTICE

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So I need to get it running, do I need to be worried about any damage? And back to my original post, what can I do about the stripped threads on the starter? Can I solder the connections?
 

Stamey

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I'm not sure what it would be other than 1 piece, so I am gonna say yes they are, with the elbows.
I am betting that I had a rush of water come up as I slowed to get a tuber.

If the elbows are bolted to the manifolds then you do not have one piece manifolds. If elbows and manifolds are one piece.... For a couple of years they used the one piece manifolds and I am told that these are a poor design which rusts through internally and allows water into the engine.
If you have two piece manifolds then it might be prudent to check your shutters, which are in the beginning of the Y-pipe.

Chris
 

Maclin

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If you got water in out on the lake it would have hydrolocked then, and you would not have been able to start it without removing the spark plugs. It more than likely has small leak inside the exhaust manifold(s), and when it was shut off on the trailer water went from the cooling passage into the exhaust passage in the manifold then on into any cylinders that had exhaust valve open. Then next time you try to start it could not compress the water and locked.
 

Bondo

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So I need to get it running, do I need to be worried about any damage? And back to my original post, what can I do about the stripped threads on the starter? Can I solder the connections?

Ayuh,.... You need to replace, either the solenoid on the starter, or the whole starter,....
Solderin' on those terminals will Not work,....

Ya gotta get the motor Runnin' to dry it out, 'n prevent it from rustin' solid,....
You'll still need to feed it water when ya do,....

As soon as ya shut it off,....
Pull the exhaust manifolds off, or yer gonna be right back at square 1,....
From what's been said, so far,.... You need a manifold/ riser conversion kit to fix the real Problem,....
 

BOWTECH.JUSTICE

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I realized last night after I posted about the rush of water on the lake that it would have shut down, so that rules that out.
It is a 2 piece manifold as the elbow is bolted on.
I did get it back together and got it running last night, so now I need to find out if I'm back to where I was before.
Just to try and figure things out, I'm not sure if I reversed and caused a back wash at the dock right before I turned it off, because I was heavy in the rear as I had a couple "heavier" people sitting in the back. Also, how much rain would it take to find the right spot and find it's way in? Just drawing straws here.
You guys are lifesavers on here and your help is greatly appreciated.
 

Bondo

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I realized last night after I posted about the rush of water on the lake that it would have shut down, so that rules that out.
It is a 2 piece manifold as the elbow is bolted on.
I did get it back together and got it running last night, so now I need to find out if I'm back to where I was before.
Just to try and figure things out, I'm not sure if I reversed and caused a back wash at the dock right before I turned it off, because I was heavy in the rear as I had a couple "heavier" people sitting in the back. Also, how much rain would it take to find the right spot and find it's way in? Just drawing straws here.
You guys are lifesavers on here and your help is greatly appreciated.

Ayuh,.... Rain water has a funny way of findin' it's way drown through the flame arrester, 'n into the motor, usually from saggin' motorboxes, or padded decks,...

Yer manifolds also have a gasket that can fail, where the riser bolts on,...
 

BOWTECH.JUSTICE

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That bulletin was very informative. Thank you.
I did find that 1/2 a shutter was missing on 1 side so I will be getting new shutters and putting those in.
We also had a fairly heavy rain that same night and even though I had it covered, there was a puddle on the cover over the engine compartment. Whether it soaked through or some ran in as I was draining the puddle off, I don't know. Seems to be lots of variables and coincidences.
I don't know how anyone can keep their sanity, or checking balance, if they are not a DIYer as a boat owner.
Thanks again guys. You've been very helpful.
 

alldodge

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That bulletin was very informative. Thank you.
I did find that 1/2 a shutter was missing on 1 side so I will be getting new shutters and putting those in.
We also had a fairly heavy rain that same night and even though I had it covered, there was a puddle on the cover over the engine compartment. Whether it soaked through or some ran in as I was draining the puddle off, I don't know. Seems to be lots of variables and coincidences.
I don't know how anyone can keep their sanity, or checking balance, if they are not a DIYer as a boat owner.
Thanks again guys. You've been very helpful.

Did you find the other 1/2 piece of the shutter? If not need to go looking for it inside the y-pipe
 

Bondo

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Did you find the other 1/2 piece of the shutter? If not need to go looking for it inside the y-pipe

Ayuh,.... When the drive is pulled to pull the motor, that 1/2 shutter will probably be starrin' ya Right in the face,...
 

BOWTECH.JUSTICE

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Sorry guys, I've tried to post 3 times now and it hasn't gone through.
I did find that a shutter was missing on one side so that is where I stand at the moment. For now I am taking it that maybe a combo of being heavy at the back when at the dock and also a fairly heavy rain that same night contributed to the water getting in. I did have it covered but there was a puddle on the cover in the area of the engine so who knows how much seeped through. As far as being heavy at the rear, 1 guy himself goes about 6'4" and probably 300lbs so if at that time, a couple others were towards the back I guess that's a possibility also. It really is unbelievable all the scenarios that are possible when having a boat. I don't know how anyone can keep their sanity, or checking balance, if they are not a DIYer as a boat owner.
 
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