Island Time

I found water/rust in the #1 cylinder on my 5.7 SB. Looks like from the riser. Do I need to tear the whole block down or just rework the heads. I rechecked compression with a good head and have 130 - 150 ft/lbs. #1 had 138.

Also I was looking at the Chevy crate engines P/N 12499529 on gmpartsdirect.com. Anyone know what it would take to use it in a saltwater environment? I could put freshwater cooling on but am not sure what else would need to be done.

thedonz

no need to tear down engine if compression is there....spray wd-40 in the plug hole and rotate the engine by hand....make sure all other cylinders are dry......then start engine....and after running pour some mystery oil or tranmission/brake fluid down the carb....will smoke up a bit, then turn off ......you should be good to go.....do leak down if possible to make sure nothing sticking in the valve train

Dangerous Dave

It's kind of hard to say without seeing it. You're probably ok if you have good compression. Did you do a leakdown test also? That will help determine if your heads/valves/valve seats are ok. Are you sure the water is coming from the riser? # 1 cylinder seems like the last place water would end up. I would think # 8 & 7 would be the most likely place for it to go. I am not a professional mechanic so please continue to seek other opinions but I also had the same problem a few years ago and it ended up being a bad exhaust manifold and I had water in #7. I pulled the heads and had them magnafluxed at Clearwater Cylinder Head on Ulmerton where we found hairline cracks around the valve seats.

Dangerous Dave

As far as the crate engine thing goes...A good marine motor should have stainless steel valves and a different cam. GM does not recomend that motor for marine use but that does not mean it can't be done. I'm sure it has been. It would be nice to know how long it would last.

Island Time

Thanks for the feedback. I actually already pulled the heads because the first time i did the compression test, the readings were all over the place. 30 in #1 to 180 in #8. Others were 90,120,140,160,etc. The inside of cyl 1 on the head was rusted. For grins, I cleaned up the piston and walls, bolted a different decent head on and re-tested compression. All cylinders tested 130-150 and # 1 was right in the middle at 138. I do not have a leak down tester.

Where do the exhaust manifolds begin to leak? Both exhaust and elbows are 3 years old. I agree #1 would have been the last place I would expect to see water.

Dangerous Dave

Stock merc exhaust starts to leak where the riser meets the exhaust manifold. The gasket goes bad after expanding and contracting over the years. Also, the parts are cast iron so salt will eventually destroy that too. Do you flush the motor religously and use an anti salt additive? Even if you do, chances are theres some salt water left in the bottom of the manifold and over time it will eat it's way through the wall into the exhaust stream. Thats what happened to me but mine were aluminum Gils and 15 years old. Pressure test them with a garden hose to see if you sprung a leak.