90 cooling system

Ok, I went ahead and put in a 3 core radiator and recovery bottle to convert to an open system. I bought the heater valve that was recommended in another article and now my engine is over heating. The top hose is hot but it dont feel like any water is flowing through the heater control valve. Is there a good diagram of the proper routing of the hoses? I used a diagram I found here and it is not working properly. Also I was wondering if I just didnt use this valve and went right into the heater core and back out again, ( like it was before ) would this be ok?

Did you install another stock style radiator or did you install a radiator with a normal radiator cap? Where is your "pressure cap" located? Did you install one of those upper radiator hose fittings? I know my 88 XJ uses a 13 lb cap, you using a 13 lb cap?

If you installed a later model XJ radiator then may need make sure you got all the air out of block. There a trick to pull the temp sensor out of the head while the vehicle if parked down hill, then you fill and the air escapes out, then reinstall sensor before starting motor.

If you went with a later model radiator how did you correct for the lack of temp sensor in the cold tank to turn on the electric fan? When you reinstalled everything did you make the connection of the electric fan to the vehicle chassis - don't ask me how I know about that mistake.... If you are running AC you HAVE TO have the electric fan working, it will overheat if it does not come on. You may want to verify the electric fan works, it should run every time the AC clutch engages, and turns off when it disengages. If it not doing that it may be a bad connection or a bad relay.

For troubleshooting you can elimiate the value to see if that is your problem area, just direct connect the hoses. My 69 Camero did not have a valve in the heater hose, it flowed all the time through the heater core.

Also if you have overheated you may want to change the thermostat. My St Louis radiator shop told me one good over heat above 225F can damage a thermostat. They also sent me to the dealer to get the thermostat.

Also do you know the age of your mechanical fan clutch. If it is over 5 years old I'd just change it since there is no good test to confirm proper operation.

I would verify electric fan operation, make sure the block is burped of air, and if still ran hot I would change the fan clutch and thermostat. Just get it all renewed.

When you installed your lower radiator hose was there a spring in it? There is a problem with some hoses sucking shut and causing it to run hot. My last upper and lower radiator hoses I got at the dealer, they were within a buck of the goodyear hoses at autozone.

Hope one of those solves your problem.