Cooling issues

1989 XJ Laredo Inline-6

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So I noticed the temp kept rising and that the electric fan never turns on.

It has 2 fans. Fan clutch and electric....

I connect the elec one to the battery direct and it works fine............

So I wire the elec fan directly to a switch and that didn't help at all. Fan runs non stop when the switch is on and there is no improvement in cooling.

But oddly enough when I idle (and have the elec fan off) and then rev it the temp drops from 200 to 180, and soon as I stop revving it, the temp rises instantly again....

This makes me think the aftermarket elec fan I'm getting Monday will be useless...

Running at 210 is normal. So if your looking to run at 180 it wont happen.

But at idle it will go into the red.... above 240.

Ranger187 said:

1989 XJ Laredo Inline-6

====================================

So I noticed the temp kept rising and that the electric fan never turns on.

It has 2 fans. Fan clutch and electric....

I connect the elec one to the battery direct and it works fine............

So I wire the elec fan directly to a switch and that didn't help at all. Fan runs non stop when the switch is on and there is no improvement in cooling.

But oddly enough when I idle (and have the elec fan off) and then rev it the temp drops from 200 to 180, and soon as I stop revving it, the temp rises instantly again....

This makes me think the aftermarket elec fan I'm getting Monday will be useless...

Click to expand...

Air passage through the radiator, or plugged core tubes are likely your problem, plain and simple. If running the electric fan made no differance then you either are not getting water flow on that side, or air is not flowing through that side.

...had the same prob, A/C fan would not come on - replaced the relay - that didn't work but found the contacts had worked loose - reseated it and now fan works

could also be a water pump issue. Might not flow enough at idle. When you rev it it flows more.

Rule of thumb, low or no speed overheat, fan clutch provided it cools down once you are moving, high speed overheat radiator.

Fan Clutch is most likely.

try a new thermostat

Since yours is a 89 you have the closed cooling system. It's technically better because you don't contaminate your coolant with constant exposure to the atmosphere. BUT they have one problem on the xj configuration and that is they trap air at the thermostat housing. That causes the thermostat to stay closed because there's not enough hot coolant around it. The answer may be just a simple "bleeding" of the air out. Driving will not do it. I got a thermostat housing off a newer xj with the ho engine and put a radiator drain valve in where a sensor would normally be to let the air out. Replace the thermostat also because it's supposed to run at 210 degrees.
Some will tell you to convert it to a open system but that will require some rigging.

JoBo said:

Some will tell you to convert it to a open system but that will require some rigging.

Click to expand...

There is no "rigging" to be done on converting to an open system it is all straight forward part changing of radiator, heater valve, recovery bottle and and moving your fan switch from the rad to the t-stat housing. And just my 2pennies after converting to the open i can see why it was only used for such a short time. My open system runs 100% better than the close ever thought of running.

87manche said:

could also be a water pump issue. Might not flow enough at idle. When you rev it it flows more.

Click to expand...

Belt tension?