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  Topic Review (Newest First)
06-03-2012 11:27 PM
BleepinJeep wow, I guess I never paid attention to the 4cyl engines. But after looking at pics of other 4cyl on the net that's how they look. I guess that's how the 4 cyl's cycle the water until the thermostat opens up. Someone smarter than me will have to tell you where exactly that goes and why.

As far as the overheating, you'll just have to diagnose one thing at a time. Sounds like it could be a thermostat, water pump, air bubble, or maybe radiator. I'd check them in that order using the techniques I used in the video. If you think your radiator is clogged then try flushing it with a garden hose and see how it flows. Also, make sure your thermostat isnt in backwards... that happens sometimes.
06-03-2012 06:51 PM
gonoles Also I discovered the shop did not plug the coolant temp sensor back in, though I wouldnt think it would have anything to do with the actual cooling system, more how it runs than anything. I ran it some today with the rad cap off trying to bleed any air. It ran for 5 or 10 minutes, all the while spilling coolant out the radiator, it never did go down like the thermostat opening. Also, after I shut it down, i felt all the hoses. The heater hoses, whatever the hose is im pointing to in the above picture, and the lower radiator hose were warm, but the upper radiator hose was cool, as was the radiator. Would this be a thermostat problem, blocked radiator problem, or is there still air in the system?
06-03-2012 04:47 PM
06-03-2012 04:35 PM
BleepinJeep I'm confused... can you take a pic of it?
06-03-2012 03:35 PM
gonoles No the one Im talking about is on the left side of the engine (left side of the vehicle). My heater hoses of course go to the right side of the vehicle where the heater core is. The hose Im talking about is rubber that goes to the intake manifold, there it connects to a hard line.
06-03-2012 11:02 AM
BleepinJeep I assume you mean the right side in the video, (I guess it will be the left side in this picture)... that is just a switch that I am using as a hole plug in my high flow thermostat housing. The other hoses are standard. the large one goes to the upper radiator and the small one to the heater core.
06-03-2012 08:24 AM
gonoles All the things in the video have been replaced on my MJ. Im going to try burping the system again today. I notice on your thermostat housing you have a hose disconnected on the left side. On my comanche i have a hose going from there to the intake manifold, what is the purpose of this line? never had anything else with something like that. Apparently it does something because I squeeze that hose and my fluid level rises.
06-02-2012 10:39 PM
BleepinJeep try this:

06-02-2012 06:03 PM
theguywithjeeps are your fans working? also try flushing the system and just take the thermostat out. if it still over heats im not sure.
06-02-2012 02:52 PM
Comanche overheating

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.

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