97 still runs hot despite all new parts

[Ben824]

My 97 XJ will run hot if it sits still. I have a rebuilt 4.0 with 6,000 miles on it. I have replaced the following with the new engine:

- CSF 3 row all metal radiator with safety cap
- water pump
- thermostat
- heater core
- fan clutch
- electric cooling fan
- Mopar coolant temp sensor

On the old engine I ran this exact same setup and the engine always ran 210 or less and never ran hot for 7 years. I only replaced the radiator after discovering a leak when I was under the Jeep one day. I had a 4 year battle with the garbage junk all aluminum radiators from champion and other Ebay vendors going through 8 of them before going back to CSF.

I am baffled why this is happening when I know this same grouping of parts worked perfect before.

 

[blondejoncherokee]

put the fan on a switch ?

 

[Digger87xj]

what temps are you seeing? Have you confirmed the dash gauge accuracy?

 

[Green Mesa XJ]

X2 on checking the sender.

Other thought is thermostat is defective.


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[Johnnie Walker]

Confirming your temp with an IR gun, and even a scan tool will let you know how far off your gauge is. Even new senders can be faulty.

 

[Ben824]

I put a the new Mopar sensor in because I had a generic parts store one in there before. The temps are not as bad as they were reading before but still creep up when in stop and go traffic. The temps get to what I would guess is 220. I know many people say that nothing to worry about but I had this exact same setup and it ran 195-205 all the time no matter what. The only thing I have different is it had a brand new parts store Made in America fan clutch and the trans has its own cooler instead of using the radiator. I also just swapped out the thermostat in yesterday to make sure it wasn't that and it still creeps up.

 

[cnugent]

I would almost expect my temps to run a little different when the system's had that much work done to it. Just because they are higher doesn't necessarily mean it's bad, unless you're having other performance problems. Just my .02.

If it runs hotter at idle, I would be inclined to think it's an airflow problem over the radiator. Could it be that your new fan clutch has affected the volume of air moving through the radiator?

 

[Green Mesa XJ]

I run a similar cooling set up and know what you mean about where the temperature should be.

Just saw this in another thread, is the condenser in good shape?

The fan is the only other factor outside a engine problem and inaccurate gauge reading.

I wouldn't think the fan clutch is the source but maybe if its not reacting to temperature.

Do the 97 have those metal fan blade that look like they could be installed backwards ?

Then the last question I'd have is about the electric auxiliary fan


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[sidriptide]

My 97 XJ will run hot if it sits still. I have a rebuilt 4.0 with 6,000 miles on it. I have replaced the following with the new engine:

- CSF 3 row all metal radiator with safety cap
- water pump
- thermostat
- heater core
- fan clutch
- electric cooling fan
- Mopar coolant temp sensor

On the old engine I ran this exact same setup and the engine always ran 210 or less and never ran hot for 7 years. I only replaced the radiator after discovering a leak when I was under the Jeep one day. I had a 4 year battle with the garbage junk all aluminum radiators from champion and other Ebay vendors going through 8 of them before going back to CSF.

I am baffled why this is happening when I know this same grouping of parts worked perfect before.

spring time is when cooling system issues start to show up.
explain "rebuilt engine". did you do it yourself locally, or is it a crate motor? or did you buy it from a guy online who said it was rebuilt?
6000 miles should be a safe wear-in period, but an engine rebuilt with "tight" tolerances can run warm until it wears in. but i think that is over-thinking your problem.

test/replace the easy stuff, especially the fan clutch. it very well could have failed, or maybe only have been marginal since new and you didnt notice it thru the winter. if it creeps up sitting in traffic it's an air-flow issue. find the problem and repair it correctly, dont band-aid it with a e-fan over ride switch.

 

[techno1154]

My one question,....How clean was the water passages in that new block when you installed it? Try flushing the cooling system especially the radiator.

I once had one those radiators. I had to replace it less than 3 weeks later because the tubes got blocked with rust from the engine cooling passages. New radiator old engine block.

Look at the other thread going right now in this forum.

 

[Kego814]

Make sure your electric fan works while a/c is on and off. If the electric fan isn't working then you'll overheat right now. I understand that it's new but all it takes is a green connection to muff that all up

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[JeepNoob]

Fan shroud in place/not broken? What about your coolant? Are you running a good 50/50 or did you just dump in a couple gallons of straight 100% because you're worried about stuff corroding? How's your belt tension? If your belt's loose, that's gonna mean both your water pump and fan are gonna run slower than normal. And honestly, yeah, 220 is nothing to sweat. 50/50 boils at around 220, but a 16 PSI radiator cap is gonna raise that by about 48 degrees...

 

[Ben824]

All parts are present and accounted for and in good shape and/or new. A/C fan has been confirmed to work and it is a brand new TYC fan. I also have an OEM fan too, there is no difference in performance between the TYC and OEM. I just did a drain, flush with cleaner, and refill yesterday. The coolant wasn't bright green but it wasn't brown, it was a dark green. I ran the cleaner through it and it came out a little brown so something was cleaned out. If outside temps are under 65 degrees it does not run hot. It was 53 degrees out this morning on my way to work and it never hit 210. It fluctuated between 195 and 205 but never hit the 210 mark.

 

[Ecomike]

I would rig up a small pump and fitting combo to isolate just the block and circulate a heavy duty block descaler through it then flush it good twice with tap water, then once with DI water, then drain and refill with 50/50....

Otherwise the crap in there will migrate to the radiator and scale it up...:shiver:

 

[puntforloss]

You probably are already on the right track with a flush. Don't forget to flush out the heater core.
Also, exhaust back pressure can cause engine temp to creep up. Sometimes a cat converter can get plugged up and cause this.
I haven't tired this, but I know there are those that swear by using laquer thinner to clean cats. Wait until your tank is half empty, put 2 gallons of laquer thinner in the tank and add ten more gallons of fuel. This will give you a 10/1 ratio of gass to laquer thinner with two gallons of LT and 20 gallons of gas mixed in tank. Drive that back down to empty and at worst you will have a little cleaner cat. At best, it may solve a backpressue problem and your motor will run a bit cooler.
Also, get a buddy and check your lower radiator hose. Have your buddy rev up the motor and see if you notice the hose collapsing a bit. The spring inside that keeps it from collapsing may need replacing or might have gotten thrown away by acident last time the hose was changed. In time, the new hose will get softer and will collapse when the pump increases the flow rate at higher rpm without the spring inside that holds it open.
Hope this helps and 'stay cool'.