1990 OMC 5.7

B

Bulldogbones17

New member
Joined
Apr 4, 2022
RO Number
34688
Messages
4
Hey guys I searched for cracked blocks and wasn't able to get an answer. Bought a 1990 ranger 395 V i/o with a 5.7. It was over a month ago and it was in PA. So I checked the oil, nice and clean. We started it up and it ran smooth. I know it wasn't started right before I got there because we had to dig ice and snow off the cover to get the boat uncovered. Get it home to NC where it's warmer and I hooked the muffs up started it and turned the water on. By now it was dark out so I ran it 10min, shut it down and shown my flashlight over everything and I noticed steam on the side of the block... yep small crack with water peeing out. So I decided can't hurt it anymore. So I'll grind it and weld it. So I removed the dipstick tube and while I was down there decided, why not change the oil. Popped the plug and I had chocolate milk. So my question is, if the engine runs as smooth as it does. Other then the intake manifold gasket, where else can there be a crack. My thinking is, there is about 100 places a pin hole crack could have formed letting water into the oil. But I'm not familiar with these engines.

Thanks
 
That engine is 32 years old. A reman 5.7 might be in your future.
 
Haha yes sir that might be the case, what is sad is this boat is in pristine shape, less the motor issue. But if I can patch it for the season. Then I can source another one and maybe do some fun upgrades lol. I mean with fuel costing what it does why not make the smiles per gallon even bigger.
 
I guess the previous owner didn’t bother to winterize or even drain it after you ran it a month ago? the good news is that you can get a small block Chevy for pretty cheap, build your self a vortec heads motor for not much more.
 
IS the engine FWC(Fresh Water Cooled) or RWC(Raw water cooled). Basically does it have an antifreeze reservoir (like a car) and heat exchanger? If so, your crack should be limited to the exhaust manifold / elbows and risers.

If not, the crack could be anywhere (intake, exhaust, block, head)
 
WALSHIE said:
IS the engine FWC(Fresh Water Cooled) or RWC(Raw water cooled). Basically does it have an antifreeze reservoir (like a car) and heat exchanger? If so, your crack should be limited to the exhaust manifold / elbows and risers.

If not, the crack could be anywhere (intake, exhaust, block, head)
Click to expand...
Its Garden Hose Water Cooled LOL, its fresh water
 
Pulled the intake manifold off and the other block had a crack in the valley. So my next question, will that stock OMC cobra outdrive handle me upgrading from a SBC 350 to a SBC 383?
 
I believe the stock Cobra is rated to 300 hp so a 383 might be too much for it. A 5.7 Vortec with a 4bbl carb from some sellers like Michigan Motorz is rated at 295 hp which is about as much as I'd put in front of a standard Cobra.
 
You must log in or register to reply here.
Back
Top