Topic: Fan - stays too cool

[MYSTANGT]

Hey guys,

I was wondering if my fan is supposed to be on all the time?

The TJ runs too cool. I have replaced the thermostat and no change. I always have a cardboard box in front of the radiator and unless 95% of the rad is covered, the temps will not get past 175-180, neither at idle nor driving.

I was wondering if maybe my fan is stuck in the engaged position and never shutting off somehow...how can i check this?

1997 WRANGLER TJ - 2.5 with a belt driven fan

[neale_rs]

What temp thermostat did you get?  It might be normal if you got the 180 degree one.  I got a 195 degree last time and the temp pretty much just stays there no matter the outside temp, hot or cold.

[sharpxmen]

What temp thermostat did you get?  It might be normal if you got the 180 degree one.  I got a 195 degree last time and the temp pretty much just stays there no matter the outside temp, hot or cold.

x2 on the thermostat, that's most likely the reason - get an oem spec one, like he said you prolly got a 180 or your current one is not closing

[MYSTANGT]

I had a 195* in there when i took it out. The new one thats in there is also a 195*

I tested both in a hot pot and both opened and closed in time...

[neale_rs]

Well, to check the fan all you have to do is try to turn it when it is cool.  It should be easier to turn than after running it with hot air from the radiator flowing over it for a while.  The thermostat could still be the problem, it might be staying a bit open all the time. Does it take a long time to warm up?

[MYSTANGT]

Not really...the only thing is that it never warms up to operating temps. It gets to 160 or so within a minute or two and stays there. I can literally let it run for 20 min and it will not go tad over 160-165...

I will replace the ECT tonight and then test the fan by hand. I am almost convinced that its the fan clutch...

Anyone know a place to get one cheap in case i will be needing one? Worth it at all to buy used or no?

[jfrabat]

It could also be that the gauge is not reading right; if you changed the thermostats, and tested them and they are working, then something is not working properly, since, even if the fan turned continusly, there should be no flow of coolant to cool if the temp is below 195*

[MYSTANGT]

My buddy just picked up an ECT for me that i will replace when i get home from work to see if it changes anything.

I believe that the TJ (being OBDII) doesnt have a separate sending unit to the gauge rather that it sends the reading to the PCM which then sends it to the gauge. So, i will see what happens although Im pretty sure thats not my issue as after driving for an hour, the coolant hoses are not hot. They are pretty warm but not as hot as they should be. I can easily hold my hand on it....

[sharpxmen]

It could also be that the gauge is not reading right; if you changed the thermostats, and tested them and they are working, then something is not working properly, since, even if the fan turned continusly, there should be no flow of coolant to cool if the temp is below 195*

x2 on this - you are absolutely correct, if the thermostat is functioning properly it doesn't matter if the fan is on at all times (old vehicles had no clutch on the fan and it was spinning at full rpm all the time).
so it's either the thermostat (either opens to soon, not closing back or not sealing the circuit properly), the gauge or sender.

[dwtaylorpdx]

The heater circuit will keep engine temp under the thermostat if your not working the engine hard.
It bypasses the thermostat on a YJ 2.5. I run a 195 but it only gets to 195 on the road,
at idle it cools down to about 170 guesstimating from the cheesy jeep gauge.
I had a bad heater hose one time and I looped the hose to get home. I tucked the
hose under something and basically kinked it like a garden hose you want to stop flow on.
It idled right at 195.

Dave

[sharpxmen]

i think the heater bypasses the thermostat on any engine and in our case is not big enough to make a big difference. My engine stays at about 190 in the winter even with the heater fan blowing full blast. If it's really cold then yeah, would be lower

[dwtaylorpdx]

I forgot, I have a heavily ported thermostat housing as well.
That may make a difference? Can't see why..

Mine only drops to 170 no matter what temperature
and that's with several thermostats over the years.

I have the reverse water pump rotation as well.

3 row radiator not the factory single or double.

Dave

[sharpxmen]

my ghetto Camaro does something like this, i changed the thermostat but it still runs cold - my guess is i got a bad one but i'm too lazy to change it again  (and it has an electric fan that never starts in the winter).

[MYSTANGT]

Well here's an update...

I replaced the ECT last night. Same thing as i figured. WILL NOT GO PAST 1650* at idle and 170-ish on the highway. Maybe 180* if im loading it up going up hill...

I did however check the fan though. When cold (stood overnight - 40* weather) the fan will move by hand. Not very freely by any means but i can move it with very little force. If i try to spin it by hand it will not turn. It will turn only while i am moving it but no matter hwo hard i swing it, it stops as soon as i let go. Is that normal?

I also did check and have confirmed that it ALWAYS moves with the RPM. Hot or cold. It spins at the same rate that the engine does no matter what. No matter whether it just started, whether i've been driving it, hot, cold, idle or revving high. ALWAYS move exactly with the RPM like the older cars did...

Another thing...i have placed a piece of cardboard in front of the rad to get it up to temps and the fan is ALWAYS strong enough that it pulls the cardboard onto the radiator very firmly at all engine speeds. Even at idle it vaccuums the cardboard onto the radiator...
What do you gents think....?

[sharpxmen]

Well here's an update...

I replaced the ECT last night. Same thing as i figured. WILL NOT GO PAST 1650* at idle and 170-ish on the highway. Maybe 180* if im loading it up going up hill...

I did however check the fan though. When cold (stood overnight - 40* weather) the fan will move by hand. Not very freely by any means but i can move it with very little force. If i try to spin it by hand it will not turn. It will turn only while i am moving it but no matter hwo hard i swing it, it stops as soon as i let go. Is that normal?

I also did check and have confirmed that it ALWAYS moves with the RPM. Hot or cold. It spins at the same rate that the engine does no matter what. No matter whether it just started, whether i've been driving it, hot, cold, idle or revving high. ALWAYS move exactly with the RPM like the older cars did...

Another thing...i have placed a piece of cardboard in front of the rad to get it up to temps and the fan is ALWAYS strong enough that it pulls the cardboard onto the radiator very firmly at all engine speeds. Even at idle it vaccuums the cardboard onto the radiator...
What do you gents think....?

that is all normal - when they go out there's quite a bit of play in them and when you spin the fan you would feel like it there's sand in there - if it turns smooth and there is no binding it's fine. It will always spin up with the rpm, the one that you are probably thinking about is the electromagnetic clutch type (like the A/C clutch) but that's not the case on the Wrangler. you can change it if you want, is not that expensive and if you have doubts you should go ahead (i had one failing on me and it's not pretty, it can take out the shroud and even the water pump bearings), but i can bet you'll have the same issue.