Rust in heads / pushrod missing

[SeattleMatt]

Hello, i just aquired a boat with a 1996 Mercurise 5.7 with closed cooling. I am in the process of bringing her back to life and i have found a few issues.

PO said they replaced the port exhaust manifold due to leaking.

How hard is it to get a cracked block with closed cooling?

Engine starts runs "ok" but does not get enough power to get the boat on plane, it's a 26 foot boat.

Took off the valve covers and found some rust in the heads, valve springs, etc. I also found a missing pushrod on the 3rd valve from the stern/starboard side. I need to look up weather this is exhaust or intake. I also found some pudding in the valve cover on the starboard side. On the port side there is a little less rust, but still some there, no puddin.

My assumption/hope is that the leaking manifolds have caused the corrosion in the head and that it may just need a valve job, pushrod, and a starboard manifold.

I assume the pushrod broke due to valve being stuck and it's floating somewhere in the oil pan.

I contacted my father who knows old pushrods better than me and he said to just get a new pushrod and throw it in adjust the valves and see how the compression looks.

I was considering just purchasing a remanufactured longblock and calling it a day, but that's going to blow half my summer.

Advice?

 

[familyguy]

Re: Rust in heads / pushrod missing

Geez man, there's a whole lot of what you just identified that blows...that engine needs a lot more than just throwing in a new pushrod and checking pressure. That thing runs "ok" without a pushrod?? I would be afraid to run that at all if I suspected metal fragments of an old pushrod in the oil pan. That kind of stuff destroys crankshaft bearings.

If your A/F mixture isn't a correct ratio in too cold a climate you can get a cracked block. If your block or manifolds are rusted through then you can get the same.

What flavor pudding did you discover?

 

[ENSIGN]

Re: Rust in heads / pushrod missing

You never got the whole story from the PO.The missing pushrod is either not there or it's laying in the lifter galley.you need to find the cause of the problem,Good luck

 

[achris]

Re: Rust in heads / pushrod missing

...If your A/F mixture isn't a correct ratio in too cold a climate you can get a cracked block. ...

And putting clothes pegs on the fuel lines will stop vapour lock.... What a load of BS!!!

If the cracked manifold (which should be on the closed cooling side anyway, unless it's a backyard job by someone who didn't have a clue what they were doing) filled the cylinder with water, then the engine may have 'hydrauliced' and you will have more problems than a lost pushrod... (which, as ENSIGN said, is laying in the valley) The if the lifter has been popped out of it's bore and you will have no oil pressure either....

Best advice? Pull the engine, strip it and access it... Determine if it's cheaper to rebuild it yourself, or put a new long block...

Chris.........

 

[JustJason]

Re: Rust in heads / pushrod missing

Originally Posted by familyguy
...If your A/F mixture isn't a correct ratio in too cold a climate you can get a cracked block. ...

And putting clothes pegs on the fuel lines will stop vapour lock.... What a load of BS!!!

I believe he means AntiFreeze ratio, not Air/Fuel.

Either way. If you found rust on the springs and inside of the heads.... the motor is probably 99% junk. It may run, but it's not going to run for long + be reliable.

Pull the intake manifold off, what's the valley look like. Any chance you can post some pics?

 

[achris]

Re: Rust in heads / pushrod missing

I believe he means AntiFreeze ratio, not Air/Fuel....

In that case, I take back what I said... :redface:

Agree with the 99% junk statement though....

Chris.......

 

[familyguy]

Re: Rust in heads / pushrod missing

Correct, seen others type A/F for antifreeze so I did the same. Realized later though if it's closed cooling rust shouldn't be too much of a factor like with an open cooling system. Agree that the engine needs to be stripped down for careful assessment.

 

[SeattleMatt]

Re: Rust in heads / pushrod missing

Just an update

I stripped the manifold off, found the broken pushrod, extracted it, sprayed and tapped on the valve till it moved freely, scraped and reinstalled intake manifold with new gaskets (lot of work), fired it back up and found the problem right away. Obviously the exhaust manifold was leaking which caused the issue, but interestingly, the now working valve blew it wide open and now my cooling doesn't work at all. I have this lame "half" closed cooling system that doesn't include the manifolds, which might be the dumbest thing I've seen Merc do so far, why bother?

Anyway, it runs quieter, less clacking, need to adjust the valves again and install the new manifold, then we'll see how long it runs for.

 

[achris]

Re: Rust in heads / pushrod missing

..... I have this lame "half" closed cooling system that doesn't include the riser, which might be the dumbest thing I've seen Merc do so far, why bother?....

So the engine block, intake manifold, heads and exhaust manifolds are close cooled. If you can come up with a system that has the risers (correct name 'elbows') in the closed cooling system, let's hear it....

Chris.....

 

[SeattleMatt]

Re: Rust in heads / pushrod missing

oops, edited to change "riser" to "manifolds" sorry...

 

[achris]

Re: Rust in heads / pushrod missing

oops, edited to change "riser" to "manifolds" sorry...

In that case what you have is someone's half-arsed attempt to recreate a closed cooling system. The Merc system includes the exhaust manifolds....

Chris........