Reply With QuoteAre the 5.7 head bolts blind tapped? If they are then I dont think the sealant matters. I though only the big block motors broke into the water jackets...
A few weeks back I found water in my oil and I can't figure out why. The engine did not overheat and was running strong. Engine is a 1987 OMC 5.7 with less than 60 hours after full rebuild. Pulled the intake and heads and all gaskets looked great with no signs of leaking. No, I did not do a leak down and now I'm probably paying the price but I have learned my lesson for the future. Took the heads to my machinest and had them cleaned, magged, and pressure checked. Came back with a clean bill of health. I cleaned up the valley area and looked closely for crackes in the common areas and saw nothing. I even had my machinest double check. What we did notice is that there was evidence of a lot of moisture in the block. The lifter bores had surface rust and there was rust under the intake manifold and along the back wall of the lifter valley. Only thing is, I changed the oil two weeks prior to finding the water and the old oil was not contaminated. The only thing we noticed was that no sealant had been used on the head bolts. Other than this, we can not figure out where the water (2 pints) came from. I figure the only thing I can do is button it back up (with sealant ofcourse) and see what happens? I figured I would ask everyones opinion while it is still apart. Thanks-Will
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Are the 5.7 head bolts blind tapped? If they are then I dont think the sealant matters. I though only the big block motors broke into the water jackets...
There was definitely signs of rust/water on the ends of the lower head bolts so they must thread into the water jackets. I could not determine if specific bolts were causing a leak as there were none that had rust running up to the top along the threads. It also seems unlikely that it is the bolts because the leak seemed to have happened all at once and not a little bit over time. But it is the only abnormal vairable we could find. Seems like I always get stuck with the "mystery" problems. Thanks-Will
i had a 350 that got water in the oil. head gaskets ,heads, manifold ,every theng maged fine. turned out that there was a pinhole in the cylendar that only opened up when the engine got up to temp. just a thought.
As far as I know, all the GM small blocks require sealer on the head bolts. If you found no sealant on the head bolts, you probably have discovered the problem.
What kind of exhaust are you running? do you have flaps in your exhaust? Did you upgrade your stock cam? Did you check your exhaust risers? small blocks need head bolt sealant for sure.
I'm running the stock center rise exhaust manifolds with aftermarket 4" thru hull tips that have flaps. The tips are above water level. The manifolds ports did not show signs of reversion-I figured there would be signs of water if they had been the cause. The cam is mildly upgraded-nothing wild. I will inspect the cylinders closely for damage tomorrow. Thanks-Will
I would probably have the engine oil cooler psi checked just in case. Sealant sounds kinda basic to me. Who would build the moter and not use the proper procedures. Getta service manual. Good luck
Good post on checking the oil cooler, a lot of boaters forget to change the zincs in the cooler and they will sometimes corrode thru and pump water into the oil. You can also close off your cooling system and use a radiator pressure test pump to pressurize the coolant side and see if the pressure drops, or more water shows up in the pan. Troubleshooting can be frustrating but rewarding!
Good Luck and hope you've solved your headbolt leaks.
Raylar
Thanks to everyone for all your suggestions. Unfortunately I do not have an oil cooler so this can't be the culprit. Once the engine is buttoned back up I will pressure check the cooling system as suggested. In the meantime, I figure if I stare at the engine and scratch my head long enough the problem might slap me in the face. Thanks-Will
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