HELP! 84 mercruiser 350 engine oil leak!
 

hello everyone! I have a 1984 chris craft stinger 260 that i have been working on restoring and rebuilding for about 4 or 5 years on and off. It has twin 350's. I finally thought i was at completion when I took it out for my first run this year and i encountered an oil leak from hell! It appeared one of the engines lost oil pressure while idling out from the loading ramp. Didn't catch the drop in pressure till a couple of seconds before the engine died. I opened the engine hatch and there was a major puddle of oil in the bilge. I pulled engine, did a bottom end rebuild, dropped engine back in. Okay now i go to start engine up, noticed no oil pressure and there was the oil again in the bilge. I found the oil coming from around oil filter. I replaced that filter with a fresh one. same thing happened again. So i pulled the oil filter adapter off as well and replaced with a new one as well as new filter once again. Well problem was solved, took boat back out and engine ran fine for about a good hour. Well today went out to run engines on hose to check everything out before taking to lake, and there was no oil pressure on the same engine and oil was in bilge again coming fromoil filter. I am at a dead end and don't know what else to do! Does anyone recognize this and no how to resolve? Help greatly appreciated!

wow... get a pro to look at it! I have no clue either!

you may have some kind of blockedge after the oil filter, is it blowing out the oil filter seal ?

yeah it is coming out over the seal. the filter is tight enough. a few times before it was causing enough pressure to loosen the filter but it is still tight and the oil is running over the filter when engine is running.

dumb question, did you make SURE the old oil filter rubber ring is not stuck to the housing? that is the only thing that makes sense to me if it is coming from between the filter and the block, does it have oil coolers? I doubt it., if it does pull off the cooler adaptor and re seal all if it.

last time i changed the filter is when i put a new oil filter adapter and new filter on. evidently something was wrong with the old adapter. i double checked for any old seal to be left on there and it was clean and slick. this evidently solved the problem. took it out for about an hour, ran fine. that was about a month ago. went out yesterday and the same thing happened. don't know it something is causing the adapter to go bad or what. i will check the filter again today for bad seal and post back on results.

ok, pulled filter, it was nice and snug but not too tight. the seal looked fine , no damage and intact. what could be causing this? could trash in the oil be clogging the oil passage way in the adapter or what? oil looked to be a little dark but not heavy. i also checked the adapter for looseness. it was ok also.

doit do it at idle? are you able to see where it is REALLY coming from when it is doing it?

it being so tight to see under twin engines, I can only see just the outer side of filter. I do feel the oil running down filter. now when engine is off i feel around and it just covered with dripping oil. i felt around oil pan after i took filter off and i don't think its coming from there. I used fram filter. think i will try ac delco and see if thats any different.

Long shot, I remember many years ago a problem with the bellhousing bolts intruding into filter adapter area. Don't know if thats your problem, just sharing a possibility.
Jim

i"ll be sure and check for the bellhousing stud. gotta get that telescoping mirror for sure because that will be a big help! thanks guys!

What are the odds of the adapter going bad so quick. I just bought it brand new from chevy dealership. it has a little bypass with a spring in it, but not sure if that causes this.

Im back after a year later and had to rebuild bottem end again. I was told that pressure was building up in the crankcase and causing the oil seal to leak. started engine back up yesterday and no leak.:drink:

thank for the idea, i think i already have the solution now, cause i just overhauled a 350 mpi, the filter o-ring is always coming out, i doubt the oil filter adapter also, i'll change it 2moro , thank for posting

i just exprerience its lately oil coming from filter, i doubt the oil filter adapter also, cause i already replace the oil filter 3 times, same problem, i'll try to buy a adater 2moro

have you overhaul both engine, somebody told me that it might be the cam shaft bearing
or the oil gallery iis clog, we are having same trouble

i have clean the oil gallery and blow it with hi pressure air, i run the engine about and its ok now, dont pour oil more than 4 liters

Sounds like the relief valve in oil pump is stuck.. If stuck, it will blow the oil filter up and split or leak badly.
Oil pan needs to come off and valve checked. Just had the same problem last week, but I was in the process of priming the long block engine thru the distributor. You could see the oil filter expand almost instantly.
Good luck
Brad

+1...this happens with high volume oil pumps. Make sure your relive valve/spring is moving freely or you will blow the weakest gasket and blow oil everywhere. Most of the time you have to pull the engine to do this. I feel bad for you on this. We are supposed to enjoy these rigs after we put so much time and $$$$ into them,,,not have all this friggin drama.

It's unrelated but I had a sticking relief valve blow a push rod tube seal out of a Porsche powered dune buggy at 2AM in the Mint 400 race in Reno, NV in '72...lost the engine before I could shut it down. Hitched a ride back to the pits with James Garner...but that's another story.

I hate oil leaks.

James Garner HUH? Do tell.