My old XJ, the one that Mysticfire has now, always rode around 185-195.  I had a 180 thermastat in it though.  Now a lot of people have the 180 thermastat and it still rides around 210, but mine didn't.  Do you know what thermastat you have in it?  You might just need to put a 195 in it.  Although even if it had a 180 in it that is still pritty low.

-- Edited by aci4369 at 20:37, 2007-09-16

Renix XJ, thus a closed loop cooling system.

Even though you have a new t-stat that is your problem. A t-stat sets the MIN. temp your engine will run at. I won't teach you on t-stats as you probally know how they work and the function of them. However your problem is that you went to your local auto-supply store and they sold you a functional, however wrong for your application t-stat.

Even though you tested it prior to install, it is not working. Why? Well you have an air pocket trapped in your motor. The air will travel to the highest point (your t-stat) and keep the pocket there. So coolant is not getting to your t-stat to allow it to open, thus flowing threw the radiator/heater core hoses. The coolant in your motor is most likely at the correct operating temp (maybe even higher), however on the Renix era XJ's the temp sensor is located on the radiator at the top driverside corner. The coolant temp at that area is going to take quite a while to get upto the 200 mark desired temp since it has to SLOWLY push that airpocket around.

The cure for this problem? Buy the MOPAR t-stat from your local dealer. Yes I know it's twice the price of the one you just bought, but suck it up and pay for it so it will cure your problems. The MOPAR version has a little "bleader" on it to allow the air to escape. You can see it at the top of this MOPAR t-stat in this picture.



Your's most likely does not have this, thus the cause of your problem.

High Output motor's have this same issue, however 90% of people are unaware of it as they have thier temp gauge on the t-stat housing and not on the radiator itself on the open-loop systems.