1990 xj with 4.0 keeps overheating...HELP

[MAF90XJ]

I just bought my 90 xj about a month ago, i have put a new radiator, 160 thermostat, water pump, heater valve, fan clutch works, and it still seems to keep running hot. its only steamed once on me and overheated but you can hear it when you stop and the pressure on the expansion champer is hissing out of the cap. Could i need to do the head gasket? I really need a good opinion.

Thanks

[Davisrats]

i would start with a new surge bottle. it should not be venting, the RENIX injected XJs are a sealed cooling system. Second, spend ALOT of time getting the water back in to the engine, the way the hoses run to the surge tank the engine block does not like to fill up. pull the top radiator hose and fill from there and/or remove the temp sender from the head until water runs out.
160 is too cold for an injected engine get the cooling figured out and go back to a stock thermostat.
does the electric fan come on? does it come on with the A/C? on the driver side of he radiator is the sender for the fan, if in doubt change it. the relay for it is on the left inner fender.
I hope this helps
Ron

[MAF90XJ]

Well thats a start thanks for the info. I bought it and it did not have an electric cooling fan on the drivers side so i did not think it came on this model but im new to the jeep world, always owned a toyota. That and i dont have a/c. I am going to get a 196 t-stat and new hoses and expansion bottle today, so hopefully doing this and purging the system of air correctly will solve my problem, im am just dreading the fact if it could be a head gasket. im going to change the oil and filter today so i will know if it is or not if there is water in the oil. But thanks for the opinion it is greatly appriate it.
Thanks,
Ron

[Davisrats]

is the fan shroud arond the engine driven fan? does it stay cool at 30 plus miles an hour?
the XJ has a history of cooling problems, but it can be solved.
Here are a couple sites, I am sure you can find more on the web...
http://jeephorizons.com/tech/xj_cooling.html
http://www.lunghd.com/Tech_Articles/..._Diagnosis.htm

[Gerr]

Tons of good info on this subject on www.naxja.org