[QUOTE=rmouton;2607142]there is also one thing that i found out with mine , is that you can get a head gasket leak into the exhaust manifold that will cause it to run hot quick..so hot that it would puke back pressure into the overflow bottle. 200,000 miles, i just put in new head and all the trimings. so far so

Mine dont puke, but i have found a used ho engine, that i am going to pick tomorrow.

[QUOTE=cherokee77;2610837]So your installing a used engine instead of trying factory cooling set up ?

With three cylinders at 40 it would run horrible and never pass smogg ....

It had the factory cooling system when these problems started. I have upgraded everything along the way to no avail, so now i will replace engine. Its my last resort.

When it passed smog, I put a brand new cat on the same day. Usually a new cat will almost always get a vehicle to pass.

Wouldn't this cause some type of smoke to come out of the exhaust pipe? Im having a similar issue with my 2000 Cherokee Sport. Give a rundown of whats going on...jeep has 124,000 on it all original notcied had a radiator leak about three months back, replaced it with a used one from junkyard alll I could afford at the time and cleaned and flushed it before installing. Coolant was a little brownish when took the old one off. but put new coolant in and all was fine. Until...

The used rad has recently started to leak as well, and motor would run around 210 instead of usual 190-195 but didnt notcie any preformance issues. I did a cooling system flush and got it all cleaned out heater core included, put some bar's stop leak in it. The leak has stopped but as soon as I did this my temp gauge goes nuts it will run between 210-225 untill Im stopped for a minute or two then it peaks to first red line. Has also done that while driving but would drop back down to 210. At first thought it was a bad sending unit, but since then it has actually overheated once on me and my girlfriend says it did twice on her yesterday. When it overheated on me pulled off the road to check it out, popped the hood and the cap was cool motor was hot assumed I was leaking and had lost my water popped the cap to first notch and was replied with an eruption of coolant and steam so my cap is holding pressure for sure, and my blow off line to the res is clear because later that day it was blowing out of the the res overflow. Been reading yalls thread here and found couple things Im going to check that I havent thought about yet, namely the lower rad hose to see if its collapsing. But any thought would be greatly appriciated low on funds and this is our only vehicle right now.

Has anyone tested the Timing?
If your timing is off it will idle all day long smooth but when under a load will overheat quickly. Not personal experience , but advice from my Uncle who's a mechanic.

Doubt it would be a cat as he just passed smog test but if its really clogged up ( glowing red at night ) wont let the engine breathe.

Please don't take offensively if I'm stating the oblivious just throwing thoughts.

I have a 1990 xj 4.0 L and was sitting in traffic got up to 210 parked and noticed the new res was low..... Also the small leak on top Of the water pump seems to have stoped ? I don't see any other leaks any where. Fans are good and kick on . Bottom hose has no spring i,but doesn't Seem to be collapsed. I heard its hard to get this hose w/ the spring ? Question is the resivore the only way to check as this is a closed system? I don't see an actual radiator cap. What's the best way to burp this system and flush ?

If you top off your open system and power brake it with the cap of, does it bubble or shoot out? It doesn't take much 2000* gas getting past the head gasket to overheat the coolant. It does OK on the highway, cruising on the open road? (thinking air-flow of course)

this may sound nuts but since your're stuck what helped for me was to change the engine fan clutch.

New engine is in, did not have time to finish yesterday. Will have it running today or Monday. Will let you guys know the results.

On BMW 5 series a trick to "burp" the coolant is to drill a small hole on the top side of the thermostat, just through the metal disc, not the working parts of it. Some coolant will pass when the thermostat is supposed to be shut, but not much. Even the BMW dealership had big problems bleeding mine. (Of course i got to my senses and bougth a Jeep )

Have you felt/compared the temperature on both sides of the thermostat? You could allso try taking it out completely for testing.

didn't see anyone suggest that the thermostat could be in backwards or the diverter valve going to the heater core. also could be the wrong head gasket off a 4.2 instead of a 4.0, water jackets are in different spots.

Yes, installed at 12 O' clock. The OEM and the good ones have that. Good point though. If I read right he said he had 40# compression on some. HG was maybe letting 2000* gas into the coolant. I suppose another engine might help that...