Starboard exhaust overheat Mercuiser 50

"I don’t think my last post

"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"

"Check the oil for water, then

"Check the oil for water, then do a compression test. I suspect there's a bunch wrong inside there. Sorry.

Jeff"

"there is no oil in the water

"there is no oil in the water or vice versa. The engine itself never overheated, it stayed 190-200 degrees the entire time. I think I have a flywheel problem. It sounds like the starter isnt engaging or I have some chipped teeth on the flywheel. I tried a brand new starter and it makes the same sound. I pulled the valve cover off and can see that the engine is turning all 4 cylinders on the starboard side. The flywheel runs so close to the exhaust that I am wondering could the heat from the exhaust screwed it up. It was HOTT when i got back to the motor. Any sugestions?
Thanks in advance
JAMIE"

"Remember that the normal oper

"Remember that the normal operating temperature is less than 180 F and if it was really hot inside the motor box when you got back there, it overheated, A coolant temp sensor in air won't read an overheat since there wasn't any water in contact with it. Steam and air are pretty bad at conducting heat compaerd with water. A flywheel won't be damaged that bad by being near a hot exhaust unless the heat is from direct contact and in that case, I guess the ring gear could be warped. Your exhaust hoses and anything that has exhaust gases blowing through need to be checked. Gear oil needs changing, bellows (probably) and anything soft.

Best thing to do it pull the motor and check it out. YOur exhaust won't overheat unless the raw water is shut off and in that case, the motor was probably smoking hot. Your motor may also have peeling paint on it and any bare metal spots have rusted. That's from overheating and since the water goes through the motor before it ever sees the exhaust, it needs work."

"did you attempt to start it w

"did you attempt to start it with water in cyls? if so you may have damaged ring gear, but also bent rod is very likely. DO COMPRESSION TEST before wasting time on starter."

"Well I decideed not to screw

"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.

Thanks
Jamie"

"Gday Jamie

Sounds like you

"Gday Jamie

Sounds like you got water up the exhaust (maybe due to an overheat), so a full tear down may not be necessary. As far as ur marine products (?) the fact is, marine engines are under far more stress than their automotive cousins (you try towing a caravan uphill for several hours). "Marine" has a price tag so its up to you what you want to pay, i dont mean that you need to purchase "marine" equipment, but you need to buy quality parts.

Cheers Spanaman"