freeworld71

97 xj-I just finished installing new water pump, thermostat housing, 195F failsafe thermostat and coolant sensor. I fired her up today. No overheating or leaks but I did notice the upper radiator hose never really got hot OR when I squeezed the hose, it didn't give much pressure back at all. The heater core hose was hot as it should be. Also, After turning the car off, I took radiator cap off and the fluid was not scalding hot as I thought it should be. Didn't even burn me to put my finger in it.

Is something wrong here?

Angus1jp

How long did you run it for? It can take 20+ minutes to get fully heated up. My inclination would be to run it for longer and see if it opens up.

freeworld71

I ran it/drove it for 20 minutes or so. I also noticed the engine temp guage went down quicker than it usually did after I shut it down. Engine was cool after about 20 min....Maybe thats correct?

BlueRidgeMark

Yep.

You might have your thermostat in backwards, or, it might be bad out of the box. It's not uncommon. Did you test it by putting it in boiling water before you installed it?

BTW, mine is hot in less than 10 minutes.

freeworld71

I didn't test it in hot water although that is a good idea. I put the spring side of the thermostat inside the head.

Am I right to be concerned that the upper radiator hose isn't giving me much feedback?

freeworld71

By the way too. My fan clutch never stopped running. It didn't do that before.

Angus1jp

The mechanical fan on passenger/right side or the electrical fan on the driver/left side?

freeworld71

The mechanical fan on left, passenger side. The viscous fan clutch or whatever. Thing keeps running.

And for what it's worth, I dont know how that thing knows when to come on since it's only connected to a bracket/pulley.

Martlor13

ummmm? I don't understand? It's supposed to be spinning when the motor is on.

freeworld71

Is it supposed to always spin? Previously it would spin then cut off for 10 seconds or so. Now it's running all the time. Is it supposed to do that?

BlueRidgeMark

It's a good thing to test them first. Even good quality thermostats are bad out of the box too often to miss that test.

Sounds like you have it in correctly.


Yes. Something is wrong.

I suggest you replace it with a Stant or Mopar unit. Some of the more experience folks on here have expressed very low opinions of "fail open" thermostats. I've never tried one, so I don't have an opinion on them, but you can't go wrong with a good Mopar or Stant.

freeworld71

I actually opened it up tonight and reinstalled it. What is the best indicator to let me know if it's working correctly? I assume the coolant sensor only measure coolant in the housing if the thermostat doesn't open up.....And this could cause overheating without me knowing, correct?

jt_aleshire

I have a fail safe t stat and have had no problems when I replaced mine I did pump hoses and t stat with a good flush

LiamLikeNeeson

failsafe can also fail closed, my mechanic has had multiple Jeeps in the shop for overheating and that was the cause.

Swim

take ur old tstat and strip all parts and install, put ur top hose on engine and stuff some pipe in end to run hot water out and away from everything. put running garden hose in cap fill and run, observ flow , adjust hose to keep rad full and flow out open end radiator, then observe temp run till everthing is steady, asumming you have hot flow out pipe...if you dont have good flow or running very hot you got blockage or bad.pump....