cj8mule
Senior Chief Petty Officer
- Joined
- Apr 7, 2012
- Messages
- 660
I'm working on a 1978 2.5L mercruiser. SN 5155605 This motor has not been used in a couple of years.
The PO had not winterized the motor properly and blew out 1 of the casting (freeze) plugs. The cold compression numbers at that time was (119, 125, 120, 130) and the oil was black with no water mixed in. I figured it was worth a shot and pulled the boat home. I put a new casting plug in and got it running on the ear muffs. It actually ran pretty good but noticed a crack in the exhaust manifold so I only ran it for a few minutes. I checked the oil and found a nice milkshake.
I pulled the exhaust manifold expecting to find a cracked block, but it looked great. I then went on to pressure checking the water in the block and it held
So, I ordered a new manifold and got her running pretty good, but still need a tune-up. I've changed the oil/filter 3 times now and all looks good.
http://www.youtube.com/watch?v=ske8nKJuHjU&feature=plcp
My question is about the variance in the warm compression numbers I'm getting now after it has ran for 30 minutes. (125, 135, 125, 145) The numbers are around 15% of each other, so I guess the motor is OK. I'm just wondering about number 4 cylinder being 145.
Should I run this motor some more and check the compression again? Or, am I good to go for an install?
The PO had not winterized the motor properly and blew out 1 of the casting (freeze) plugs. The cold compression numbers at that time was (119, 125, 120, 130) and the oil was black with no water mixed in. I figured it was worth a shot and pulled the boat home. I put a new casting plug in and got it running on the ear muffs. It actually ran pretty good but noticed a crack in the exhaust manifold so I only ran it for a few minutes. I checked the oil and found a nice milkshake.
I pulled the exhaust manifold expecting to find a cracked block, but it looked great. I then went on to pressure checking the water in the block and it held
So, I ordered a new manifold and got her running pretty good, but still need a tune-up. I've changed the oil/filter 3 times now and all looks good.http://www.youtube.com/watch?v=ske8nKJuHjU&feature=plcp
My question is about the variance in the warm compression numbers I'm getting now after it has ran for 30 minutes. (125, 135, 125, 145) The numbers are around 15% of each other, so I guess the motor is OK. I'm just wondering about number 4 cylinder being 145.
Should I run this motor some more and check the compression again? Or, am I good to go for an install?
