View Full Version : Rebuild on a 1991 50L GM

05-17-2006, 09:16 AM
"Well I decideed not to screw around and pulled the engine, I pulled all the pluggs and the water just poured out. The good new I hope is that withe the pluggs out I can turn the motor over with ease and it appears to be very smooth. I will break it all down tonight and am going to do a complete rebuild. I do however have a few questions for my 1991 5.0L.

1. The exhaust manifolds are in great shape. I am considering hot tanking them etc. and keeping them. Is this ok?

2. Can I run all regular GM parts for the inside, i.e. }rings, bearings, and that sort of stuff or for all the internal engine parts?

3. Do I need to stick with the marine products when replacing the water pump etc.


05-17-2006, 09:26 AM
Check the water pump- you may not need to replace it. Look at the exhaust manifold gaskets for leaks- it's possible that the water came into the cylinders through them. GM parts should be OK but the parts store will want casting numbers and anything else that identifies the motor.

Was the motor running on after turning the key off? It's possible that it rotated backward at the end when it was trying to stop and injested the water at that time.

05-17-2006, 09:40 AM
"What happened was

Posted on Tuesday, May 16, 2006 - 09:31 am:

I don’t think my last post went through. I have a 1991 5.0 mercruiser in a Trophy. The starboard side exhaust overheated on me. It melted one of the rubber 4 inch sleeves, froze the shift linkage, and appears to have done something to the flywheel or engine. The motor turns over but it makes the sound of metal being hit with a sledge hammer. The motor diesled when I shut it down and it sucked saltwater. I have the lower unit off as we speak. It all looks good except the shift linkage needs to be replaced. I think I need to pull the motor and start looking at the flywheel and work my way forward. I will need lots of advice on this one; I just can’t bring myself to pay $71/hour for service at the dealer. Does anyone have any suggestions? I know I need to replace the exhaust manifolds and risers. What do I need to do regarding the saltwater? How should I attack the engine to get it going again so it can visit the SALE MARKET?
Thanks a bunch Jamie


So I went ahead and pulled it so I could just go through it so it will last another 15 years with no problems."