5.7 Liter Blown Head Gasket, Mech says need new block (pics)

[Crownline_242]

2001 Mercruiser 5.7 Liter 2 BBL about 450 hours
Never overheated, Oil pressure always normal

Put boat away last year, everything normal. Included oil change and full gas tank and gas additive when winterized. The yard does not fog engines for the winter
Changed plugs, cap, rotor in spring
Take out boat for Shake Down cruise and heard fairly loud pinging, then brought the boat back in
Check oil (level OK, no water),Re-gap plugs, check wired correctly, retry…still pings.
Compression test Port F-R 180, 180, 180, 180 , Stbd F-R 180, 30, 30, 165

Mechanic takes top end apart and says I need a new block because of the corrosion towards the top of the cylinders. I also noted that there was no rust in the exhaust manifolds

Any opinions on the requirement for a new block based one the pics?



Any opinions on the requirement for a new block based on the attached pics?

 

[Rick Stephens]

I don't see no stinkin corrosion.

Not sure what he is talking about. I'd redo the thing in a heartbeat. Pictures of the head would help as well.

 

[Searay205]

I would check for flatness if in within specification put on new head gasket and use. Looks beautiful to me. Heads off get resurfaced anyway.

 

[Bondo]

and heard fairly loud pinging,

Ayuh,...... Welcome Aboard,....... What I can see in the pictures looks rebuildable,......

The pinging is detonation, which is most likely the cause,.......
Probably detonation from a lean condition, but I guess over advanced timin' is possible,....

 

[kenny nunez]

I also vote for just getting the head cleaned up also. As far as the pinging do you think that you may have crossed 2 plug wires during the tune up? I also suggest going through the carburetor while the engine is down. Double check the timing when it gets running again. There are plenty hours left on the engine’s life.

 

[jgrote]

As others have said, from the pics it looks perfectly serviceable. He's trying to sell you a new engine. However, it's a little tough to tell how deep those pits are. But at this point, you have little to lose by putting a new HG on and giving it a shot.

If it were mine, I'd have the head checked, slap it back together, and see how it did. I would then check for blowby into the crank case. (smoke coming from oil breather.) Next, I'd send some oil off to Blackstone to see if there are any signs of excess combustion gasses in the oil.

 

[tpenfield]

The mechanic may also need to have his head checked

 

[Scott Danforth]

first, get your compression gauge fixed. anything over 150 psi on a good gauge is debris or oil or water in the combustion chamber

second, get yourself a new mechanic.

third, take heads to a reputable machine shop and have them serviced.

 

[Howard Sterndrive]

Maybe roll the engine and look where that piston at tdc is before condemning the mechanic.

 

[Crownline_242]

Team,

Thanks for your feedback so far.

Rick Stephens, kenny nunez, Scott Danforth – Heads - I am planning on redoing the heads regardless since they are off. I will try to stop by the marina for pics today

kenny nunez – Crossed Wires - it is possible the wires were crossed although they were double checked as it would have not been the first time that has happened to me. Only question is that I could not figure out how the crossed wires would have made the pinging noise…unless that is what was responsible for the head gasket to blow

Bondo – Pinging Sound - The ping I heard was much louder than a typical knock. I originally was hoping that my fuel went sour. Thanks again for your help. You helped me on a different forum about 10 years ago

Scott Danforth – Compression Readings. I also thought that the readings were a bit high. It was a new compression tester from AutoZone. I guess I found what I was looking for regardless…2 cylinders down, the rest within a reasonable range.

The shop owner has not given me a quote yet as I suspect they may be rethinking things. I went back to the boat last evening and I noticed that they removed the blown head gasket from the boat

 

[Lou C]

I’m in agreement with the opinions stated in fact I did a similar job on my old 4.3 V6 3 years ago. It had a bad overheat in 2013, ran fine for 2 more seasons and then blew both head gaskets in 2016, with water in a cylinder but not enough to hydrolock. I took it apart and had the heads checked by a machine shop. They found both heads had cracks in the center cyl exhaust valve seat area, and the cooling parts were eroded from years of raw water cooling in salt water. The block deck looked good as did the cyl walls and pistons. Valve lifters and cam lobes looked like new. I installed a set of reman heads with Fel Pro head & manifold gaskets. Turned out well. Yours looks repairable but you must determine the cause of the blown HG or it could happen again. If it was a lean condition you need to correct that. Make sure the boat is not over propped and that your max wide open throttle RPM is within specs.