View Full Version : cooling problems xj

02-02-2008, 10:06 PM
my friends and i all have 89 xj. and we all are having problems with overheating. i hear its fairly common is there a better way, bigger rad or better water pump or what. any info would be appreciated...
:rockhorns: [cheers]

02-02-2008, 10:12 PM
upgrade to the open system. I did it to my 90, haven't had a problem since

Taz Jeep
02-02-2008, 11:29 PM
[iagree] Had the same problem with my '89, got the rad, hoses and thermstat outlet from a 2000 XJ at Gary's in Maple Ridge for $100 cash :D

Haven't had a problem since. [cheers]

02-03-2008, 12:09 AM
so what is the main problem with the older xj cooling system.

is it just the closed system that is the sore spot in the system. I have a 90 and running into the same problems...

02-03-2008, 12:29 AM

02-03-2008, 12:38 AM
Yea you got some real problems if your overheating in this fucking weather.

02-03-2008, 12:47 AM
ok thanx fockers. go fuck yourself

02-03-2008, 12:52 AM
yeh ill switch to the open system . thanx . and roc go fuck yourself i guess we wheel harder than you mam! it dosent overheat till im diggin uphill hard. but my zuki and my chev both dig hard but dont overheat.

dirka dave
02-03-2008, 12:02 PM
Believe it or not, if you are over heating in the cold weather, it is usually because the lower rad hos is freezing. Why ?, well the lower rad hose is exposed and when you are driving around the speed that you are going is the wind chill factor. Antifreeze will help lower the freezing point, an open rad system can actually do more damage. 1 - If you leave the rad cap loose, you can not build the 5-15psi the cooling system needs. (works on the principal of convection). 2 - If you pull out the thermostat, you are not letting the coolant stay in the rad long enough to either cool down (summer time) or warm up (winter time cold start). hope this helps. [cheers]

02-03-2008, 12:58 PM
The closed system sucks if you have even the slightest blockage, Especially commmon if your heater core isn't eficient because the bypass in the system is fucked so the coolant won't circulate properly.

dirka dave
02-03-2008, 01:14 PM
Not so true, the little tube under the rad cap will allow any air bubbles to pass into the over flow. Only works if the rad cap is operating corectly. There is also a bypass built into the waterpump or a bypass hose so that coolent and air can flow and so that any air will go to the highest point in the system, the rad cap. [cheers]

02-03-2008, 10:07 PM
The 87-90 Renix closed coolant system in the XJs is very hard to get all the air out of the system it doesn't circulate the water to the expansion tank on the fire wall well, any air in this system and they will overheat, and the expansion tanks are very prone to cracking which lets air into the system.

The best fix is to upgrade to the 91 and newer over flow tank and pressure cap system they bleed out the air alot better and keeps the coolant system topped up with antifreeze.

A quick fix to try on it, providing the expansion tank is not cracked, get yourself a 5/8inch flusher Tee and a couple of hose clamps, take the heater hose that goes to the thermostat housing at the top frt of the cyl head in frt of the valve cover and cut that hose in the middle put in the flusher Tee take the cap off of the Tee and hold it up about as high as the expansion tank and fill the coolant up the tee will now be the highest point in the cooling system and will let all the air out of the system, once coolant starts to come out of the Tee put the cap on it and fill the expansion tank about half full.

02-10-2008, 08:10 PM
i picked up a 99 rad and all the gear. ill put it in and see what happens.