exhaust / coolant manifold for 1978 OMC 400 GM 3.0 140HP

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mrbiggdaddy

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after 6 years, got my '78 galaxie tri-hull out of storage. Decide it was worth way more than the 800-900 I might could get selling her. So I got her cleaned up. Got her tuned up, new plugs wires, dist cap, points, fuel tank flushed, time for oil change....I pumped out 5 qts of water and a quart of oil sludge out of it ----I couldn't believe it. I had accidentally flooded the inside rinsing her out..left the hose running and drain hole got clogged. So I figured water must have got in as the water level got all the way over the oil pan..half way up the block level and was that way for at least an hour before being discovered. So I put new oil in, ran it with muffs on, sucked out basically good oil with no water. I figured it would be milky from running with water muffs if there was internal compromise to crankcase. So I changed oil filter, put new oil back in it. Got it running great, oil was clean after idling 30-40 minutes on muffs....soooo Took it out last Sunday for sea test, and ran fine, but didn't run long as I didn't check sterndrive oil levels, didn't trust myself. Bought 9.9 HP 4-stroke Honda kicker and it bracket mounted. Then yesterday, I had the sterndrive oil levels topped off and got trained how to do same, then invested $200 in new prop and hubkit. Fixed up trailer lights. Bought tubes and lures. Told the boys to buckle up their fishing belts for Saturday Lake St. Clair smally, walleye, and tubing expedition. Did an oil level check after hooking boat up at my shop......and it's chocolate milk. water in my crankcase!!!!!! so the water I pumped out wasn't from me flooding the boat...it was from my sea-test last Sunday. cracked block? my neighbor who knows something thinks the crack might be in the upper manifold to allow water into my crankcase? is it part number one in this drawing? If not what. Anyone with a parts engine for me? HELP?! Please and many thanks in advance.

Ray
 
Bondo

Bondo

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Re: exhaust / coolant manifold for 1978 OMC 400 GM 3.0 140HP

cracked block? my neighbor who knows something thinks the crack might be in the upper manifold to allow water into my crankcase?
Click to expand...

Ayuh,... I'd think it's a cracked block,...

If it's the manifold, all the water would have to seep past the piston rings...
 
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mrbiggdaddy

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Re: exhaust / coolant manifold for 1978 OMC 400 GM 3.0 140HP

OK....thank goodness, I found out what happened. My neighbor asked if I ground out the boat / had prop strike during my sea test last Sunday. No. I didn't... He said that sometimes on a prop strike the engine will convulse and suck in water though the exhaust manifold...doesn't take a whole lot to make it white.

I got home and asked my son, who drove the boat in a holding pattern while I got the trailer backed down, if he had run aground while he was driving, and he said YES, they ran through a seaweed patch that hung them up for a little bit.

Sooooo, I pumped 5 qts of choc milk out of crankcase last night. filled up with clean oil..took her out again this morning and ran her around hard for an hour or so.

No water in oil..

The old OMC is fine for a few more years. :rolleyes: :)
 
Nivekt

Nivekt

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Re: exhaust / coolant manifold for 1978 OMC 400 GM 3.0 140HP

Howard Sterndrive said:
?
that's a new one to me.
Click to expand...


Yeah, I dont even see how that would be possible. Dont let your guard down MrBig. Keep an eye on that oil. Pump it out after every trip to be sure.
 
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