Lucas21

Story is I bought this 88 XJ a few weeks ago knowing that it overheated (got a REALLY good price on it). When I checked it out the coolant bottle had a gash in the side, the electric fan didn't work, the thermostat was stuck closed, and the radiator was horrendous. Basically, I knew I had my work cut out for me and it was no surprise that it had an overheating problem.

I first changed out the coolant bottle and thermostat. Gave it a burp and it ran alright for about 10 minutes before it would start to overheat. Got a 2-core radiator for it and just got the fan working the other day. Now it runs good for quite awhile but once the temp gets to the 210 mark (ie operating temperature) the coolant tank starts spraying coolant. Could it just be a faulty coolant tank cap? It has went through it's share of overheatings as I've been troubleshooting this thing through.

Thanks guys!

BlueXJ

If you suspect the expansion tank of having a defective tank and you want to never buy another tank again then try this. CLICKY

milmat1

You should wait on the experts but I will add this:
the 210* Temp is normal for the Jeep, I don't know why the overflow bottle would be spraying at that temp Unless like you said the Cap isn't working?? Does it have an Aux Electric fan also?

Lucas21

I know 210* is normal, hence why I'm suspecting the overflow tank cap is faulty. Yes I do have the auxilary fan and it is working.

Basically, up to this point I have been having problems with it overheating, now it gets to normal temp and then starts pissing coolant.

ETA: Thanks for the link to that coolant tank. I may consider it in the future but believe it or not that tank would cost almost as much as what I paid for the entire XJ :P The current one has been holding pressure nicely up until it sprayed coolant last night. I still didn't see any cracks in it or anything to indicate that the tank is bad, too.

BlueXJ

The bad thing about those plastic tanks is that once they have been crossthreaded they become unreliable for future sealing.

theangler

Get a new cap first off I'd say. After that if you want to work out all the possible weak links in your coolant system, water pump? I'd do that for sure especially if you're changing the radiator and everything else.

Lucas21

Waterpump is new and there are no symptoms of it being faulty.

Lucas21

Does anyone have a suggestion on a cap to get? Would one from CarQuest or an auto parts store work alright or would I be better off getting an OEM one?

Thanks for all your help guys!

Lucas21

^I appreciate the help but I think we are talking about two different "caps" here. I'm asking about coolant tank caps. Looks like you are talking about ignition.

milmat1

Replace the Bottle cap and the Radiator Cap! The radiator cap has an expansion spring that allows the coolant to flow to the bottle when needed, It could be bad..

c-loss

milmat he has an 88 xj which has the closed system so no radiator cap with it. i had this same problem until i bought a new tank and i have not had the problem since.

paroxysym

i stick with OEM on this... order a new one and a new tank from the tank...

LimitedXJAddict

also make sure that your temp sender is working, I had one that was broke inside the brass collar so it wasn't giving a true reading. In fact I discovered it was broke when I went to check the voltage and pulled on the connector and the sender came out of the collar.

87 XJ

I had that problem before on my 87!!! It was fine, then one day it starts over heating. Didn't know what was going on. Turns out my year old cap was cracked and not holding presure. Replaced it and all is fine now

Lucas21

How much pressure should the cap be able to hold?