Overheating

I have a problem. When I sit at a stop light, my heat guage goes :flame:way:flame: up. I filled up my coolent, it just started doing this...I don't know why. Any ideas?

Thanks.

Hows your radiator? My 90' started out like this then got progressively worse.
Bought a new rad. from www.radiatorbarn.com for about $105 S&H included, had it within 24hrs. Solved my problem.......of course b-4 shelling out $$ for a new rad. I would go thru the process of elimination.

Check your thermostat or buy a new one and gasket (fairly cheap). Not saying there is but check for leaks. You could have a bad radiator or water pump but don't go there yet. You could flush the Rad. Make sure you have water and coolant aswell. If all else fails you might need to get a new radiator and maybe a water pump. A friend of mine also had an over heating problem on hot days on the trails. Turns out it was leaking fluid the whole time. don't run your engine long if it is overheating because then you run the risk of warping the heads I believe.

How about your electric fan, is it working properly?

Does your temperature drop down once you start moving again? As someone who has gone through every single XJ cooling problem and finally overcome all of them (with help from people on ), I can tell you that if your temp only goes up when you are sitting still, your fan clutch and/or electric fan are probably malfunctioning. The fans are responsible for forcing air through the radiator when you are moving slowly. If your temps drop down again when you start moving, this is almost certainly the problem.

fan clutch!!!!!!

X2 on fan clutch

Overheating at highway speed = Circulation - radiator (restricted) or water pump.

Overheating in traffic or wheeling = Air flow - Aux. fan not coming on OR fan clutch.

What year? Motor?

Renix = cracked pressure bottle/air in system.

Post 91/Pre 96 = heater valve.

Post 96 = ??

I believe I have a coolent hose leak. I fill up the res, then a little while later after driving for a bit, the tank is empty.

Well the tank will be empty as the system draws in the fresh coolant when the remaining coolant in the system compresses. When it is hot it expands and goes into the overflow, when it is cool it compresses and goes back into the system.

Keep filling until it stabilizes and never completely empties.

Not to jack the thread, but with the renix how do you get the air out? i already replaced the bottle and cant find any other leaks, so i am thinking there must be air trapped in the system?

im not sure on the renix, but on my 95 i just cleared up an issue i was having (today) with overheating. over the weekend i did a cooling system flush. as i drove to work at 430am, i began to overheat and it continued both at freeway speed and at intersections. the xj did the same on the way home from work-98* for todays high temp. i went and got myself a new radiator cap. the one that has the pressure relief safety valve (red plastic lever on the top). i was able to "burp" my cooling system by SLIGHTLY lifting on the lever. as soon as i did, i could hear the air escaping into the overflow tank. after it was done "burping" i let the vehicle sit for about 15 minutes. after that, i looked in the overflow bottle, and it was empty. i refilled and after 20 minutes of idle i am not overheating.

hth
stewie

OZNAD said:

Not to jack the thread, but with the renix how do you get the air out? i already replaced the bottle and cant find any other leaks, so i am thinking there must be air trapped in the system?

Click to expand...

Yea, it's a hijack, BUT:

1.) I've yet to read what year the OP is driving. If it's a RENIX then this is relevant.
2.) To alleviate the air-in-system problem, take out the thermostat, drill a 1/16" (1/8"?)hole in the thermostat at top and bottom (AKA 12 o'clock and 6 o'clock of the face of the t-stat, not the edge). Re-install the thermostat. This effectively burps the RENIX closed system. Drive fill, drive.
3.) A properly working thermostat only regulates MINIMUM temp. Unless it's stuck closed or partially closed (unlikely) the thermostat is not the problem.
4.) X2 on the 16 lb cap but that won't work on a RENIX (no radiator cap) and a non-RENIX will burp itself in normal driving. Monitor your overflow bottle after every trip, even to the store.
5.) A pressure bottle is not an overflow bottle, it'd be easier to diagnose if we knew what you were driving, please include in your post. If I missed that, Im sorry.
5.) On my 90 (RENIX) I had a pinhole leak that was only evident when it was hot and running. When I turned the engine off the pressure would dissipate quickly and the stream of coolant went away. There was some coolant in the engine bay but not on the ground. After replacing 2 coolant bottles (cheapies admittedly) I converted it to an open system in aggravation.

...and finally, if you're overheating at a light or in traffic or wheeling at slow pace it's more likely your fan clutch OR your aux. electric fan.

...and then there's always the possibility of a head gasket failure...but we won't go there on this post since I have no experience with mine on this. So that's all I got.
eace:

You gotta burp that Renix until it is really, really full. The tank is not plumbed well to allow air to naturally percolate up to it - that's why when you fill it, later, it's empty again.

Open systems without a catch bottle will do the same, even worse. They keep losing coolant until you get a overheat condition ( and yeah, I know better now.)