Help me find my leak!

[MadPikAvenger]

Greetings all,

So I have a 1995 Bayliner 1750 with the 3.0L Mercruiser (serial #0F287053) that I've been having issues with water getting into the oil. No visible leaks on the outside of the engine. I checked the compression and got the following results:

Cylinder 1 (front of boat): 170
Cylinder 2: 170
Cylinder 3: 170
Cylinder 4 (rear of boat): 60

I put some oil in the 4th cylinder and the pressure rose to about 80 one time and on another test a couple days later jumped to about 120 but was less and less with each test.

I realize I probably should have pressure tested the cooling system and all that but I was too excited to start taking stuff apart that I pulled the head and manifold hoping to find some obvious (to me) problem. Of course I didn't so I'm hoping all the great knowledge and experience you guys posses might be able to help me out.

Here's what I did find. The exhaust manifold only appears slightly corroded in the passage that the water goes through and not anywhere else. The riser looks a little corroded in both passages (not sure if that is normal)

Also there was obvious oil on the exterior of the engine near the 4th cylinder. I attributed this to oil/water getting blowing up through the "vent" in the valve cover. It can be seen here:

Here's some pics with the head off:

Here's how the valves/gasket looks (4th cylinder is on the left):

I put some gas in the 4th cylinder with the head upside down and it appears it leaked past the valves:

And finally I noticed that the head gasket was firmly stuck to the all the way around except near the 4th cylinder near where I observed the oil on the exterior. In this area it looked like this:

I haven't checked to see if the head is warped at all yet but is the condition of the gasket in that area a sign that it wasn't sealing properly?

So my big question is what does this all mean and what could the source of water in my oil be? If any more pictures are required just ask.

Thanks!

 

[Josh P]

Re: Help me find my leak!

ya looks like head gasket, your piston is really clean and combustion camber is wet looking. I would send the head out to a machince shop they will check it for flatness cracks and valve seat grind. I would also check the cylinder wall with the piston all the way down inspect for cracks as well

 

[Josh P]

Re: Help me find my leak!

ive circled the areas where it looks like it may have been seeping.

 

[achris]

Re: Help me find my leak!

Maybe... But I doubt that would have let water into the oil. Re-inspect the exhausts manifold and elbow again, and this time REALLY check them. Water in #4 is usually a sign of a leaking elbow, and at 7 years old, that's where I'd be starting. Your compression figures are a concern, but that may improve when you get the engine running again.

Would love to see some photos of the elbow/manifold gasket and mating surfaces, and some of the insides of each.... The head gasket may be a symptom, not a cause....

Chris......

 

[MadPikAvenger]

Re: Help me find my leak!

Thanks Josh P and Chris! I'll snap some pics and get them posted up later today.

 

[MadPikAvenger]

Re: Help me find my leak!

Would love to see some photos of the elbow/manifold gasket and mating surfaces, and some of the insides of each.... The head gasket may be a symptom, not a cause....

Not sure if this is anything. Looked particularly oily/wet in this section.

I haven't gotten the old gasket between the manifold and riser cleaned off yet. The gasket between the head and manifold came off easy and didn't appear to have any noticeable issues.

More pics below.

 

[MadPikAvenger]

Re: Help me find my leak!

Here's the pics of the riser. Thanks again!

 

[achris]

Re: Help me find my leak!

Wrong elbow gasket!!! See how one side has a partly covered water passage, and the other side of that passage is open to ...the manifold.. That, my friend, is where your water is getting into the engine....
So glad you didn't clean that gasket off! Would never have seen it if you had....

EDIT: Correct gasket number is 27-997772.

 

[MadPikAvenger]

Re: Help me find my leak!

Wrong elbow gasket!!! See how one side has a partly covered water passage, and the other side of that passage is open to ...the manifold.. That, my friend, is where your water is getting into the engine....
So glad you didn't clean that gasket off! Would never have seem it if you had....

EDIT: Correct gasket number is 27-997772.

Chis to the rescue! Glad my laziness paid off for once. Much thanks my friend!

My (hopefully) final question/s: Is there anything else worth doing while I have the head and manifold off? Do the exhaust manifold or riser show signs of needing replacement? Would it be worth having the valves checked or just decoke it well and let it be?

Is there a gasket set available or is it better just buy the head, manifold, and riser gaskets separate?

Thanks again!

 

[achris]

Re: Help me find my leak!

The rest of it looks fine... I'd just get the head checked out, maybe a little re-lap on the valves (and make sure #4 exhaust valve's not too rusty). The manifold and elbow look great, just clean up the surfaces and throw some new gaskets on and you should be fine. I'm just hoping the cylinder walls and rings on #4 aren't too badly rusted either, but time will tell... I would be putting it back together and taking it on a long run. Hopefully the rings will re-bed themselves and you'll have a happy season...

If you want to buy the gaskets separately, as follows is the Merc numbers.

Head gasket -> 27-8010841
Manifold gasket -> 27-96429
Elbow gasket -> 27-997772

Chris......

 

[Don S]

Re: Help me find my leak!

Be careful when you put it back together. It's not so much that you had the wrong gasket for the elbow, your old one was on backwards.

Compare the remains of your gasket to how a new gasket looks.

 

[MadPikAvenger]

Re: Help me find my leak!

Thanks for all the help! New gaskets on order. Hopefully the machine shop will have a quick turn around time so we can get back on the water.