Another OMC 3.0 cooling issue!

Ok Guys,
Bought a 94 Sunbird OMC 3.0 for $750. Been sitting for 4-5 years I'm guessing. Pulled plugs, oiled cylinders, wouldn't start, tracked it down to a starter problem. New starter, turned it over w/o plugs, insert plugs, prime carb and it starts right up. Ran on hose boot, temps and oil pressure ok. I noticed water from under manifold and casting plug was missing. Replaced plug, leak stopped. Took it to the lake and ran it for about 1/2 hour at no more than 3k rpm and it ran fine. Temps and pressures ok. Oil pressure flucuated a good bit, so checked the oil when I got home. It was creamy, so I changed the oil and filter. Took it to lake again yesterday and ran fine. Up to 3500 rpm this time. Let someone else drive and I checked the engine carefully while underway. Noticed a slight leak from water circulating pump weep hole, and slight leak on port side of block coming from under manifold at front of engine. When I got home, oil was creamy again. Previous owner said he winterized the boat before he let it sit, but I wonder...
My question, do I need to immediately find source of leak, block or manifold, or both, or can I run it lightly, keeping the oil changed, for the rest of the season, and do a rebuild this winter? Either way, looks like I'm going the short block and new manifold route sooner or later. Still I'm thinking a pretty good deal for $750, trailer is probably worth almost that much.
Thanks for a great forum.

Re: Another OMC 3.0 cooling issue!

Your block is cracked. He did not winterize it properly.

Running it for the rest of the season is up to you because you are going to wipe out the internals because of lack of lubrication eventually.

Re: Another OMC 3.0 cooling issue!

Thanks for the input Bruce. Yeah, that's kinda what I figured. I expect to rebuild it completely this winter, or buy another motor. Hate to not use it to putt around the lake every two or three days for another 3 - 4 weeks. If I keep the oil changed every other day or so, will that do irreparable damage to the pistons, rings, crank etc? We just retired to the lake and I want to show my girl a little of it before the winter. She's not really into the paddling around in the canoe!

Re: Another OMC 3.0 cooling issue!

I'm back! Over the last couple of months, I have torn down the motor to the block. It appears that the leak I thought was from the exhaust manifold was actually from the head gasket. After pulling the head, I realized it was blown between 2 and 3. I cleaned everything and examined the head and block very carefully. The cylinder walls look fine, as well as the mating surfaces of the block and the head. I can see no signs of cracking on either. I ordered the parts to put it back together and am looking for input into what else to do. I am not going to be able to pull the block right now, so is there any way to check the block for cracks other than visual inspection? I'm hoping that the freeze plug popping out may have prevented any major damage. Is this a pipe dream? :]. Worst case scenario, I'm only out the money for the gaskets if there is a crack, and best case...it's fixed.
I appreciate any input. It's almost boating season down here and I'm ready to get this beast on the water.

Re: Another OMC 3.0 cooling issue!

Well,I would have probably done a pressure test on the water passages before I pulled the head. You can reinstall the head with a new head gasket and do it. If you find a leak you basically wasted your time with the head. If the water jacket is cracked internally, you will never be able to exammine the block visually and find it.

Re: Another OMC 3.0 cooling issue!

Thanks Bruce for the reply....yeah, after the fact I read a post by Don about the pressure testing. The older I get the more I "for"get. In my earlier days, I would have remembered to do the pt first. I'm guessing that I plug the line from the thermo to the ex manifold and inject air to the thermostat? Maybe I'll get lucky and there are no cracks. Down here in Ga, it very seldom gets colder than the teens, so maybe...

Re: Another OMC 3.0 cooling issue!

I'm guessing that I plug the line from the thermo to the ex manifold and inject air to the thermostat?

Click to expand...

Ayuh,... Ya gotta block Both the out-goin', 'n the In-coming waterlines....

Re: Another OMC 3.0 cooling issue!

Thanks guys...probably be a couple of days bf I get to it. Been a cold snap down here...lows in the 25-30 range and I don't have the closed in garage I used to have. You know how us southern boys are...can't stand the cold. I'll let you know the news, good or bad.
Really appreciate the replies. I'll post some photos of the cleaned up boat shortly. It's got a nice line to it and seems to ride on the water well.

Re: Another OMC 3.0 cooling issue!

Shadowfax said:

Down here in Ga, it very seldom gets colder than the teens, so maybe...

Click to expand...

It will freeze sooner than the teens!

Re: Another OMC 3.0 cooling issue!

Hey guys, quick question to anyone who may know. I got the head and thermo housing on and ready to put the ex/intake manifold on. The parts schematic from marineengine.com shows two gaskets and one restrictor between the elbow and the manifold. The restrictor is not available and I emailed the guy from marineengine who said he couldn't get the part and didn't know if it was necessary. I dont recall seeing one when I broke it down, so I'm wondering if anyone knows if the restrictor is mandatory. I'm still learning on I/O's and can't wrap my head around the need for a restrictor. If it is mandatory, any ideas where I could get it. The guy suggested I check ebay, but the only ones available on ebay show only one elbow gasket.