cold engine

i got a 87 with the 4.0. it is running really cold. like 120. i know this aint good but dont know what could causing it. i dont nothing about engines.
TIA

i forgot to add that its a rebuilt engine. it was done before i got it.

120...all the time? I don't think that's possible unless there's something wrong with your gauge.

Time out!

Scot, you didn't post where you are located. Does your temperature gauge read in Farenheit or Celsius? Normal operating temperature should be in the straight-up position, which is 210 degrees F, but 100 degrees C.

i live in california.and yes the gauge works. ive only got 1 fan right now. and sometimes i gotta pull over for a while cause it gets to hot.

I thought you said it was too cold?? When is it that it's 120? Do you have the stock radiator? There's no way your engine can be 120 unless you just turned it on.

well unless the gauge is just wrong. but it does work.not sure if they replaced the radiator when they did the engine or not.but yea round 120 is what the gauge reads some times it goes up to about 160

So 120 after it's warmed up and when you're going down the road? If so unless you've got some MAJOR cooling mods your gauge is wrong.

well is there a way i can check for mods are the accuracy of the gauge?

Something here is not adding up. As I posted above, in English units the normal operating temperature for a stock XK is 210 degrees F. That's the middle point of the dial sweep, so at that temp the needle should be straight up.

Your first post said your XJ runs too cold, at 120 -- then you follow up by saying that

... sometimes i gotta pull over for a while cause it gets to hot.

Click to expand...

Which is it? Too cold or too hot?

Please tell me what the numbers are on your temperature gauge. It's an outside shot, but I just want to be sure you don't somehow have a metric gauge, and that we're not all on the same page here.

210 is straight up on the gauge. i said it over heats sometimes when im drivin around town because im only runnin with one fan right now. normally it runs with the needle not even close to 210.the needle does work because the temp goes up a little bit after its been runnin awhile. the engine was rebuilt bout 40,000 miles ago.

Since you've just had the cooling system broken and filled, try this (I did read right and you have an 87, right?)

Look at the driver rear of the cylinder head for a small copper-coloured plug with a wire. Unscrew the plug, and see if you get a water trickle. If there is no water over the sender, it won't read even if you do overheat.

Second, was the thermostat changed as well? Was the cooling system "burped" afterward? I suppose one could get a large air bubble - maybe large enough to make the sensor in the head for the gage not work!

Since you are having overheat problems anyhow, change the thermostat. Before you put it in, drill two 1/16" holes in the metal flange on the new thermostat directly opposite each other. Install the thermostat with one hole at 12:00 and the other at 6:00, and the system will purge itself of air as it runs. This works fine for me on an 87, and 88, and an 89, so I'll swear by it.

With the early "closed" systems, it is all to easy to get an air bubble, and the "closed" system is fairly rare in automotive circles until very recently, so not all mechanics know an easy way to deal with it.

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yea its a 87.the thermostat was changed. ill give your suggestions a try asap and see what happens. thanks for everyones help. if it doesnt work ill be back.

It sounds to me like you have NO thermostat, and a partially clogged radiator.

California where?

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