Water in oil. Intake gasket?

[danond]

Here's the status:

- 1989 OMC Cobra 4.3 I/O
- Water in the oil
- Oil stinks like engine exhaust after only a few minutes of running
- Compression is between 155 and 170 on all cylinders
- I've changed the oil twice
- Previous owner swapped a 4bbl intake for the 2bbl that was there
- Engine was well cared for, serviced and winterized, then stored in heated garage
- Engine runs perfectly, starts perfect, no hydro-lock that I've experienced, has 50psi oil pressure at idle
- After 20 minutes of idling the engine won't warm up at all, stays very cold, even to the touch. I think the thermostat is stuck open.
- Heads haven't been off the engine
- Freeze plugs still have original paint, aren't leaking or distorted

If the intake manifold wasn't installed properly it seems like it could be loosing water into the lifter valley. Has anyone seen this before?

Is it possible to have good compression with a bad head gasket?

Can you guys recommend any further testing that I could do to eliminate a few more things before I tear into it?

 

[Bondo]

Re: Water in oil. Intake gasket?

Ayuh,....

Block off,+ isolate the Block's Cooling system,+ Pressurize it with Air,.. About 10/ 15psi.....

Then Listen,+ follow the sound....

 

[danond]

Re: Water in oil. Intake gasket? Update

Re: Water in oil. Intake gasket? Update

I did pressurise the cooling system with the garden hose method tonight, my hose puts out about 75psi. I turned the engine over little by little and waited 5 mins each time, nothing came from the plugs. Not that it's terribly relevant, but it was dead quiet, too. No "running water" sounds anywhere.

When you say pressurize do you mean the cooling system and the cylinders?

Thanks for the response, by the way.

Edit: nevermind, took me a minute to process the words. You mean the cooling system. I need to drink more.

 

[danond]

Re: Water in oil. Intake gasket? Good news!

Re: Water in oil. Intake gasket? Good news!

Update - Bond-o I did what you suggested, drained everything (found what was left of my thermostat in the lower hose during the process) and pressurized it with around 15psi of air, then sealed it and let it sit for about 20 mins.

Couldn't hear air coming from anything, so I went inside, made a sandwich, watched boring women's tennis and after about 30 mins went out again, opened the valve I'd put in the line and whoooooosh all my air came back out.

Now I'm wondering if my exhaust flappers have gone bad. My plugs were rusty (not all of them) when I took them out. I replaced them, and there's not been any water in the cylinders since.

Here's my assumptions:

- No air leaking anywhere and good compression means 90% sure the block and cooling system is OK (except for the termostat, which I will swap today)
- Rusty plugs means water did get in the cylinders
- If exhaust flappers were bad, that would allow water into cylinders where the exhaust valve was open, explaining the few rusty plugs
- I didn't change oil before firing it up the first time this year, which would explain why the oil suddenly went milky (assuming water had drained down into the oilpan from the cylinders). Mistake, I know. Only ran it for 10 mins. Have mercy.
- The very strong fuel smell in the oil suggests my fuel pump is bad.
- I changed oil on a slight slant (just noticed). I am probably leaving a fair amount of nasty oil in the pan.

Anything else I should check?

 

[HT32BSX115]

Re: Water in oil. Intake gasket?

(Same engine as the "other" thread right?)

It's very possible that the water in the cyls (that had open ex valves ) came from a leaking riser gasket (or cracked ex manifold/riser....although it's very hard to get more than a few oz of water into the oil this way as it has to get past the rings.)

I had the very same problem with my previous OMC engine. I had water leaking into open exhaust valves via bad riser gaskets on both sides. It woul dhydrolock every time I restarted the engine after being off for about 15 min or so. If I let it sit for an hour or more or over night it would start right up (indicating the water was leaking right past the rings) It never caused milky oil though. The little bit of water that did get past the rings did evaporate out every time I ran it afterwards.

Once you determine that the block is NOT cracked or t the risers etc, I would look to the intake manifold & gaskets like you indicated and possibly a cracked head/blown head gasket. Good compression usually rules out head gasket problems though.

Fuel pumps with a cracked diaphragm usually will allow gas into the engine and you should be seeing gas in the tube that runs to the carb. If you don't have a tube to the carb, then it's missing or it's an automotive pump and should be replaced with a marine pump whether it's bad or not.

Cheers,

Rick

(btw, did you know that OMC is out of business?) JUST KIDDING!

 

[danond]

Re: Water in oil. Intake gasket?

You are a forum nazi. I like you.

Since I have the one-piece manifolds I'm guessing I don't have riser gaskets...

At this point I'm close to ruling out a busted block, and the air pressure test tells me it's probably not the heads, but I haven't ruled any of those out 100% though I'm not going to focus on that being the problem anymore since the remaining test is to start removing big parts. I'll save THAT joyride for last.

I'm going to try to pump the oil out again and change it one more time, I don't think I got it all the first time.

I also think the previous owner regularly ran the engine without a water supply, which from what I've read burns the flappers out. I already found a cooked impeller and a bubbly impeller housing. Yeah, it got that hot.

I do have the clear line to the carb, I *think* I can see droplets in it. I ordered a new fuel pump today to be sure.

Question - is it possible with the one-piece exhaust manifolds to remove the rubber exhaust connectors without removing the manifolds?

 

[HT32BSX115]

Re: Water in oil. Intake gasket?

Yeah those one piece OMC manifolds are a pain (and $$$ too) (if they're old....the're still suspect....manifolds can look good on the outside and be rusted thru on the inside.)

Yes you do cook all the rubber and the flappers in the Y-pipe if you put exhaust gasses in there without mixing with water.


You might be able to slide the rubber couplings up or down without removing the manifolds but I don't think there's enough gap to get in there and remove/replace the flappers...I think you really have to remove the manifolds to get in there. (don't drop anything in there or you'll play 'ell getting them out) You know once you get the rubber hoses slid down enough to see.....

 

[danond]

Re: Water in oil. Intake gasket?

Changed the oil today with the nose of the boat in the air - that was the problem. I didn't notice until today but the boat sits nose low on the trailer when the trailer is level, allowing the nasty crap in the oil pan to sit in the front section of the sump.

Lifted it up, changed the oil again, and walla....no more crap in the oil.

With a good thermostat it heated right up. Oil pressure stayed at 50psi, temp was around 170 on the gauge. Shut it down, let it sit for 20 mins, fired right back up with just a touch of the key. Oil is crystal clear.

Assumptions:

- Previous owner couldn't get it to start (bad points) so he pumped half a quart of fuel down into the engine. Explains the fuel in the oil.
- Previous owner was bad about not changing oil, went 2 seasons without a change, so with that and the bad thermostat not allowing the oil to get hot, the condensation in the oil was making it get milky.

Going to the lake tomorrow for a test run. If the flappers are bad that's my last thing to fix. Whew what a PITA but not a bad gamble. I got the boat for a STEAL because it wouldn't run. Figured I'd play my odds and it looks like I came out on top.

I'll post another update after the test run.

 

[danond]

Re: Water in oil. Intake gasket?

Test run was excellent. 4 hrs on the lake, no serious issues. Looks like I need to seal up the transom, so I'll order a full seal kit with bellows and whatnot and fix that, service the u-joints while I'm in there, check the gimbal and so on.

Oil is still crystal clear.

Thanks for all the help, guys.