OMC 2.5l

[dschuma72]

I have a 2.5l OMC that I've been having problems with water in the oil.

The end of last season I had a problem with the boat not starting after a short ride from the dock at very low speed. Water was coming up between the exhaust manifold and the head. I took the exhaust manifold off and noticed there was a freeze plug that wasn't seated evenly, I took a socket and beat the freeze plug in so it was the same depth all around. I thought that may be where the water was coming from so I put the exhaust manifold back on with a new gasket. That fixed the problem of water spurting out from between the head and the exhaust manifold.

I had to make a gasket for the riser elbow from a rubber gasket material.
After having it back together, I didn't get the riser elbow tight enough, because I could see where water was seaping out where I put the gasket I had made... I took that back apart and made a new gasket again, but this time I tightened it harder and it doesn't seem to be leaking water anymore.

The problem is I still get water in the oil. I almost tore the head off thinking there must be something wrong there. Good thing I didn't because I don't think that's the problem anymore. Here's why...

I also had a starter problem and the boat was starting very rough, took many attempts to turn over. I put a new starter in it and if I keep the boat at high rpm I don't seem to get any water in the oil.

The thing fires right up with the new starter, shouldn't it hydro lock if water is getting in the oil through the exhaust?

Any help is greatly appreciated.

Thanks

 

[Bondo]

Re: OMC 2.5l

and noticed there was a freeze plug that wasn't seated evenly,

Ayuh,... That's Freeze Damage,.... My guess is, you have More Freeze damage, Internally...

 

[dschuma72]

Re: OMC 2.5l

I guess it could be freeze damage, but it was still September and we haven't had a freeze yet. It ran fine all summer and I winterized the boat every year.

I was just reading that starting the boat out of water for any period of time is bad. I always thought you could start the motor and let it run for 30seconds or so while out of water without any damage. Could any part that fails from starting out of water have anything to do with this?

If I fire the boat up and take off from dock instantly, I can run it all day without water getting in. I actually ran it for almost a week with no water. Then my starter failed on me again and the boat was rough to start, right away water was in the oil.

I called all of the local shops to see if I could get a pressure test of the cooling system done to try and isolate the problem. Nobody around here has the equipment to do that. I could probably build the pump setup to do it myself, only problem is I'm unsure of how to block it off, and exactly where I should block it.

Thanks for the help Bondo. I know you're probably right, I must not have winterized it correctly and it just caught up to me at the end of the season. I'm just still shooting for stars and hoping I don't have to tear the motor apart.

 

[Howard Sterndrive]

Re: OMC 2.5l

I had to make a gasket for the riser elbow from a rubber gasket material.

whatever the case, get that crap out of there and use a proper gasket. don't risk an engine to save $4

The problem is I still get water in the oil. I almost tore the head off thinking there must be something wrong there.

Tearing the head off NEVER reveals much of anything. You pressure test the cooling system with everthing assembled. Never take the head off until you have completely diagnosed the issue.

The thing fires right up with the new starter, shouldn't it hydro lock if water is getting in the oil through the exhaust?

sounds to me like the brand new starter is strong enough to overcome the extra compression where the older starter wasn't

The rubber gasket you made is probably leaking water into the exhaust.

You don't "tighten harder" on cast iron parts to stop leaks. You need the proper gasket and torque.

 

[dschuma72]

Re: OMC 2.5l

Thanks Howard, I didn't even think to order the correct gasket.

I actually did purchase one from the local OMC guy in town. I installed it and water was in my oil like I've never seen before. Here the gasket wasn't totally correct for my exhaust manifold. There was an interior ledge in the riser elbow that the gasket I purchased did not cover. The OMC mechanic didn't have the correct gasket and told me to just go buy gasket material and make one.

I'm going to order the new gasket and I'll let you know if that was the issue.

Thanks again, my hopes are high here that this is the problem.

 

[Howard Sterndrive]

Re: OMC 2.5l

The OMC mechanic didn't have the correct gasket and told me to just go buy gasket material and make one.

did he say when my lawn mower would be ready?

 

[dschuma72]

Re: OMC 2.5l

He's actually been around for many years, I think he was just setting me up for failure. When I look back on it I'm pretty sure he knew he was giving me the wrong gasket at first.

I was actually very surprised at how helpful he was, about 5 years ago I went to his shop and tried looking in the service manual on his counter and the guy threw a fit, saying that's how he makes his money and such.

I'll let you know the outcome. Thanks