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PCM 4140 Mitsubishi overheat

funder13

New member
"My friend's engine overhe

"My friend's engine overheated. We had checked the raw water impeller - it was in good shape and fairly recently replaced - and had the heat exchanger boiled out. It still overheated in a big way.
I pressure tested the cooling system and it did not hold pressure. (I put my ear to the oil filler and heard bubbling sounds???)
The circulating water pump seemed fine. I pulled the head and found that the head gasket was in fine shape with no gaps. The head and block had no obvious leakage areas between cylinder and water jackets.
The #4 cylinder had the erosion around the exhaust port mentioned here and pretty extensive corrosion on the exhaust valve stem or guide. One local machine shop said it wouldn't work on the head, with the erosion on #4.
So we are left with a few options:
1) Put it back together with new seals and pray. If it doesn't overheat, we won't know why it did so. If it does, we are out the time and parts.
2) Get a new/rebuilt head. I can't find a listing on line from the links from the discussion back in May.
3) Get a used engine from the salvage yard.
4) Get a new/rebuilt short block (does that include the head?)

Any ideas where to search for the source of overheating, and parts?

Thanks.

Jeff"
 
"That number 4 cylinder is the

"That number 4 cylinder is the culprit. Mine had acted the same way. Buy a head, go online to tri cylinder and pick up a complete. Transfer the camshaft and camshaft holders over to new head. Your problem will go away. Make sure you replace the zincs in the heat exchanger and the exhaust manifold."
 
"Hey Joe ,anyway to stop this

"Hey Joe ,anyway to stop this corrosion around #4 from getting this bad,kind of nip it in the bud??my engine has 10 hrs on it,thanks Chris"
 
"Chris , I have been in commun

"Chris , I have been in communication with someone who has put another s pipe between the muffler and exhaust manifold. Just have no way of knowing if this will help without ripping her apart again! I have thought of installing a tee fitting on heat exchanger and use compressed air to blow out the water after a run. Cylinder number 4 sits at the lowest point and belive moisture is the culprit, along with disimilar metals, even with gasket in there!"
 
"So Joe it sounds like it is t

"So Joe it sounds like it is the water that gets traped in this area,wonder if this is why they stoped usind this motor,mine is a 87 model,do you know when they stoped making this model? thanks again for all the help,Chris"
 
"Joe can you tell me a fram ol

"Joe can you tell me a fram old filter # for the 4140,i took the original to the parts store and they cant match it to anything,thanks Chris"
 
"Hello guys. Glad i finaly fou

"Hello guys. Glad i finaly found somebody talking about this motor. Could anybody tell me some info on this motor? I just bouat a 1987 sunliner with the 4140 pxlt motor and know nothing about it. I been trying to find a exhaust gasket for it since running it for the 1st time, I found it had a leak at the exhaust gasket."
 
"Wheres the leak? Last cylind

"Wheres the leak? Last cylinder towards rear of engine? If so keep reading the posts in this forum, most if not all info has been posted here. Type in the search field pcm 4140.
good luck"
 
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