AutoRetro

Hello, The other day i checked my coolant, admittedly for the first time as my heaters have become less effective over the last few weeks to the point they were just blowing cold. I would normally associate this with head gasket problems or an air lock. I use my jeep to pull a big trailer and only dragged another cherokee back on it about 100 miles last week, she never gets hot and always runs perfectly on lpg and petrol. So i havnt had any concerns about major issues with it. Today i decided to flush the cooling system and refill with fresh pink antifreeze. I also flushed the heater matrix and the radiator through with a hose. I then drove around 5 miles to check everything was ok and the temerature rose and continued to rise untill it got to the top. i stopped, some steam was coming out from the top hose and the smaller one connected to thermostat housing. i removed the thermostat but this was working fine. i have checked the viscous and electric fan are working. It will idle fine but overheat as soon as you drive and still regardless of engine temp blow cold air through the heater. I know this is all a bit long winded but hopefully gives you a rough picture.
If anyone has any help on this matter i would be very gratefull as i am now a bit stuck without it especially over Christmas. in advance many thanks.

DFlintstone

Just tossing out a couple things to start. Was fine until the change? Gotta suspect air. Sometimes I park at different angles. Mine is pretty different. I idle mine for a bit. Let it cool. Top it and check again soon.

That "hot right away".....If you fill it right to the top then "power brake", with the cap OFF , watch for bubbles. (just like it sounds, gas it some with the brake's pressed full on) (takes two), If the Head gasket were letting 2000* (F), gasses into the water jacket it will bubble or worse. Some "surging" is normal, but sustained bubbling means that supper hot combustion gas is going into your coolant when it's under load. Heats it up fast.

jdjonesdr

I'm with Flintstone.

Sounds like air in the cooling system to me too, if all you did was change coolant.

BimmerJeeper

How do you bleed an XJ system? Just remove the radiator cap and start it and let it heat up?

DFlintstone

90 and earlier Renix just has our "time bomb" , Expansion tank. No "pressure relief. (Renix folk don't fill it! (Really, leave it 1/2 empty). 2/3 rds air is OK). Or 1/2 full. It NEEDS air in there. I'd just park the 94 with the cap up/higher. Fill it, let it idle to temp, let, let it cool, then top it and watch it.

I did mean top the radiator. You can "top" the overflow tank, no harm but no point ether.

AutoRetro

thanks for the advice, the more i think about it, it must be air. in my impatience i didnt let it cool properly once just filling it running it and spewing it all back out again. its been sat all evening now and in the morning i will check the level and see how it is. I have a sort of expansion tank with a useless lid that used to be empty so i filled it about half full maybe more, could this be affecting it?

Firestorm500

"90 and earlier Renix just has our "time bomb" , Expansion tank."

HAhahahahahah! I still wish this forum had a "like" button.

The Rooster

its so true...