Join Date: Jan 2005
Location: Willow Spring, NC
Ive got an 87 Comanche with the 2.5L. The engine was just put in a couple days ago, and I'm having overheating problems. It has a new water pump and thermostat, and a fairly new radiator. If I start it up, within a minute or so the water will rise and run out the open cap, or if the cap is on, fill and overflow the reservoir. If it is driven for 10 minutes or so it will boil the radiator and overheat. The radiator was brand new and only driven for 50 miles or so 4 years ago. In that time we replaced the water pump with a reman, and that reman ate itself. The impeller was eating away at the pump body causing an overheat then. The radiator and water pump were installed 4 years ago due to an overheat problem on the old engine (we installed a different pump after that one ate itself back then and it still overheated). It is not the unit we put on this engine just installed, it was out of the box new. I'm wondering if there is a blockage in the radiator due to metal filings. If you squeeze the top or bottom radiator hose it does make the fluid level change some, not as much as i would think but some. This engine was pulled from a YJ wrangler and runs good, but has the same overheat problem as the old engine. I dont think its a blown head gasket, its not mixing water into the oil, has good compression, isnt smoking, and when the cap is off the radiator, its an even fluid rise, no bubbles and no sludge. Could an air pocket in the block from it being dry for a month or so between the YJ and MJ cause a fluid rise and overheat? If so what is a good way to burp the system? Im pretty much stumped as to why its doing this. Even with the new parts and different engine, it has the same problem from 4 years ago. Any help is graciously appreciated.
1982 Jeep DJ-5L, restored; 1987 Jeep Comanche Sport Truck, 2.5L 4cyl; 1980 Jeep CJ-5, 258 T176 Dana 300; 2012 JK Unlimited Rubicon RHD