A little background. 1989 454. Through hull exhaust. Port exhaust steamed more then starboard on same motor. (starboard motor no steam either exhaust, same motors, less then 300 hrs since rebuild 6 years ago. No issues on either motor.

Last spring, motor ran good the first couple hours out. Then starter began making noise and would sometimes have a hard time turning motor over. Replaced starter. Boat ran good. 3-4 eng hours later... same starter issue... on oil check found water in oil. located water in #7, all others dry. No water ingestion when running. Took topend off, had head maged, head good, gasket looked okay, but perhaps suspect in one place. New gaskets and correct assembly. Good compression test all cylinders. Ran good for 3 or so hours. Suck my head under hatch, kept hearing a "ticking". Tried like hell to find where it was coming from. Found water in #7, not in oil. Ran got up to temp. Shut down, open drains in exhaust manifold. No water. in 7. Replaced exhaust manifold and riser. Ran up to temp, ticking and water back in #7. Ran up to temp again, shut down and open drains, ticking goes away when water is drained. Its fall at this point, so I pulled the motor, drained it of all fluids, found water in 3, 5 and 7, all others dry. This happens if it in the water or on muffs.

Im only finding water in the port side. Head was maged, its good and straight, replaced the riser and exhaust manifold. The starboard side of the motor has always been dry. Cylinder walls look good. Only thing left is to have the intake manifold maged. Im hoping it the intake manifold and not the block.

Any thoughts, experience, advice??? Im out of idea's. A couple of my buddies who are ASE certified mechanics are also scratching their heads. Any help would be greatly appreciated. So far there is no sign the block is cracked, but havent taken it completely apart yet and am hoping I don't have too.

Thanks

Exhaust manifold cracked internally dumping water into cylinders. Then draining past piston into oil pan???

yes exhaust or maybe the head is cracked but only leaks when hot and expands

He replaced the manifold and riser, same results

I'd check the cam lobes. You could be losing a lobe, and reverting water because of it. I've seen bad lobes show decent compression on a gauge still even though they were going flat

Yup. And since 5 + 7 follow each other in firing order, they are more likely to revert. ie: suck in water.

BTW: I would have also pressure checked the head and exhaust.

I guess I took it as he just reassembled them back on the motor when he said replaced.

No, replaced with new.

Yes, this all happens when the motor is hot. Does not happen when I run it 5-6 minutes from the ramp to the dock. Replacement of the exhaust manifold and riser eleminate them. I have also wondered if a crack in the head only opens up when it gets hot, but shouldn't magnafluxing the head find that even when cold?

Im wondering if anyone has ever seen a intake crack? Has anyone ever maged one? This motor did backfire a few times in the past, but the carb was fixed.

I have had a cracked head that checked good with magnaflux. I think the most common way of checking a head or block nowadays is to pressure check it. The magnaflux is a quick way to check if u are buying some heads from Jim bob and wanted to check them!! Every machine shop I have been to has plates for pressure checking.

Magnaflu is only as good as he person reading it. It will show a crack that only opens up when its hot. Since it is only one cylinder I would be looking at the head. Valve guides can leak water and hard to detect. It sounds like you are checking everything. Unless you are in salt water, I doubt an intake would leak water. My 2cents.

Update: Had head pressure tested, found cracks in the exhaust valve guides on 5 and 7. Lesson learned? Save the headaches and have them pressure tested. Thanks for the input everyone.