Hey Guys I am the new owner of a 1992 Mitsubishi MiniCab U42T /657-cc/3G83/Auto/ 4x4. I have been following the forum to help troubleshoot a few issues. I am at a point now where I just want some confirmation before I go for a head gasket change. I noticed I did not have any heat, no matter how long I let the engine run. It seems I have zero coolant flow. I can pull hoses off the thermostat housing while the truck is running and nothing will flow out, this is with and without the thermostat installed. The coolant level is also full. Pulled the water pump, it looks fine. I am able to blow coolant through the system with compressed air so I do not think I have any blockage. I am thinking maybe there is an issue with the head or head gasket? -Oil seems fine, no coolant in oil, even dropped oil to double-check -Coolant seems fine, no oil in coolant, dropped coolant to double-check but it looks like a fine metallics in coolant. -Very small bubbling happening in coolant overflow tank when the engine is running -Compression check with all spark plugs out, #1 155 PSI, #2 165 psi #3 155psi -Cylinder leak test, #1 in green around 20%, #2 in yellow around 50%, and can hear slight bubbling in over flow #3 in yellow around 65% can hear slight bubbling in overflow I am thinking I need to replace the head gasket but I wanted to hear what you guys think. The engine actually does run good and my compression seems fine. I only started to look into this due to the no heat issue.
Well, I decided to take the valve cover off to check the torque of the head bolts but I found a new problem. It looks like one of the valve adjustment screws is missing (attached is a picture). Looks like I am going to have to drop the oil pan now to see if it's around. Anything else I should check while I have the oil pan off looking for this screw?
I would plasti-gauge, the main and con rod bearings, and then re-torque them. And, rotate things around to see what the inside of the cylinders look like. It would let you know what kind of wear the engine has.
So it looks like it was a blown head gasket. I pulled the head, cleaned everything, noticed the some of the valves did not seal properly so I also pulled all the valves, cleaned and lapped them too. Put it all back together today. It runs a lot better now and I actually have heat. Looking back at it, when the truck was cold it seemed ok, as soon as it warmed you could see the rad overflow blowing little bubbles in the container. Something must of prevented the fluid from circulating once it warmed up and stated blowing the little bubbles. I think the last owner knew there was an issue as there was lots of fine metallic in the rad fluid. I was told this was probably some sort of leak fix additive. I checked the compression and its around the 170-180 mark now.
