QUIKDECISION

I know that this subject has been covered extensively. I have read through all of the posts i can find, and I am still batting zero. Anyone with any thoughts, would be MOST appreciated. I have 454 mags that have been bored 0.030 over. Engines completely rebuilt. New Extreme marine roller cams, 112 LSA. Oval port 781 heads. Larger valves, Inconnel exhaust, extreme duty stainless intakes. I have been through 3 sets of different heads. Fel pro marine 1037 ( I believe) Head gaskets. New guides. Heads magnafluxed. Blocked decked. Edlebrock air gap intake manifolds with Mr gasket intakes. Revolution Marine aluminum exhaust. I have had this boat going on 5 years and cannot make it out without water in the oil. The rebuilds were complete last summer. Made it out 3 times. I had hp-500 cams, LSA 110, and I had reversion constantly.
With the new cams, I believe I have cured the reversion. Now, I have 1 engine that renders milky oil on the garden hose. I pulled the plugs and one side shows signs of water, the plugs are really clean and white on cylinders 3,5, and 7. I performed a pressure check on the exhaust manifold, and it was good. I looked in the riser and can see no signs of water tracks. I pressure checked the block today. I blocked off the openings behind the water pump with steel plates. Blocked the thermostat housing with a half inch thick aluminum plate and cork gasket material. I pressurized the block to 22 lbs. It leaked down to 18 lbs after 4.4 hours. Is this normal, or should it hold pressure longer? I know that pressure checking the block cold, is not as effective as when warm. Most of the previous threads/postings warn of leaks around the intake manifold. I cannot be assured that i don't have an intake leak, but that wouldn't account for the clean spark plugs. The identical twin does not exhibit this problem.
Again, any thoughts would be MOST appreciated. QD.

ljsmith1

My first guess would be a head gasket. Second would be intake manifold.

A far shot would be a cracked block.

Good Luck!

jmherbert

An intake manifold water leak would most likely not be seen at the plugs. The water would drain into the lifter valley and straight into the oil.

If your block or heads have been decked, the intake manifold may have to be machined down to fit proper. Also, if the intake, heads, or block is warped or not flat, that would cause your problems.

If you end up having to tear it down, have the parts checked for flatness.

If you pull just the intake manifold, remove all the gaskets and bolt it to one head, then measure the gap on the other side with feeler gauges. I don't know what the gap should be, someone else may know, but it is should be the same at all points across the mating surfaces.

Liquid Liability

Any idea what your water pressure is when you are running? You could be blowing water past your head gasket if the pressure is too high. There have been a couple of boats in my area that had that problem & they also all had FelPro gaskets. A switch to Cometic (sp?) head gaskets and a water dump cured the problem.

teddy38

sounds like exhaust. i would pull the exhaust manifold and check again. see if the port on the manifold looks white. check with a garden hose why its off. good luck.