1990 4.0 xj Running hot on hills

I would like some suggestions in determining what is causing this, I do have a new waterpump and a new recovery bottle. hoses all appear to be good. What should I look for any and all suggestions are welcome. When I climb the hill to get to my home the needle would climb to about 240 degrees, As soon as i start declining, I notice that the temperature needle drop gradually in a matter of minutes back to normal temperature. The climb up hill is about a mile of steady climbing in the Virgin Islands.

hills in the virgin islands? anyway. I had the same prob. I just flushed the system. refilled with clean and all is nifty. Hows the mud in the rad fins? wehn i flushed mine it was a tasty gray brown

running hot in the V.I.

I did flush the radiator about 2 weeks ago, and changed the water-pump and fluid. However I did not clean those fins that you are mentioning. I attempted to at the same time, but I found them to be quite soft, is that normal for those fins.

An increase in operating temperature is normal and expected when ascending long upgrades. The auxiliary fan should kick in to help offset that. Do you have an aux fan? If so, have you confirmed that it is operating? It should kick on at about 217 degrees.

BTW -- minor nitpick: On a 1990 you don't have a recovery bottle. That plastic bottle is part of the pressurized cooling syste. When you replaced it, did you also replace the cap? It's best to replace both because often an old cap won't seal to a new bottle, and vise versa.

yes those fins are soft but you can take a garden hose and spray in through the front and they will be ok. You will be amazed at all the junk that comes out of there.