95 cooling questions

[macgyvr]

Disclaimer: This jeep is only ran on the trail, so if it seems like there is great amounts of time in btw trying something new, its cause it doesn't do road time.

Owned this jeep since 99 and never once did it over heat or even run hot until last summer. It was just running warm when it all started, I was at Camp Jeep in MO in the mountains in extreme heat and using the a/c on the trail, so I didnt really think much about it. Later in the fall I noticed it running warm on the trail but winter was coming so again I didnt think much about it. Ran it this winter and it stayed cool.

This winter finally checked the electric fan and it was burnt up. Replaced it this spring and either a relay or sensor burned up and it wouldnt come on automatically. Wired fan directly to a switch in the cab. Hit the trail in April, with fan running all day Jeep was still running hot.

Last week replaced the coolant,tstat and radiator. Was on the trail on Saturday with the fan running all day the motor would stay around 210 until I got on it going up a hill or gave it gas the temp would immeadiately go to the edge of the red zone.

I just changed the oil also, it hadn't been changed since last october and with 240 miles on it, there were no signs of a blown head gasket.

The radiator is 3 years old, it was a brand new stock replacement when it was replaced, so I suppose it could be bad already.

This rig shouldn't be overheating, any help.

mac 'its not even warm outside yet' gyvr

[GreedyXJ]

Check your fan clutch

[macgyvr]

Oops forgot to mention the fan clutch appears to be ok...

mac 'too hot to handle' gyvr

[martin]

Mac,

There is no good way to test the fan clutch. The problem you describe sounds like lack of cooling air through the radiator. The consensus on this board is those fan clutches last 5 years and should be replaced.

Sometimes it is the stuff right in front of us.

Martin

[macgyvr]

I'll go get one and give that a try, that would be great if that's the problem, an easy fix, as I dont want to replace the radiator again if its not the problem.

mac 'coolin my britches' gyvr

[martin]

Mac,

Once you install the new fan clutch you also need to replace the thermostat and radiator cap since you got the engine hot. The bimetalic springs are most likely damaged.

You most likely will see the temps swinging after you install the new clutch if you don't change these. I was going to change the radiator 3 years ago because of the temp swings after an over heat until the radiator shop guy asked "did you change the thermostat and radiator cap?"

Martin

[macgyvr]

I changed the Tstat and cap just before this last trip, it never got into the red on the last trip just right before it.

On this fan clutch thing, a buddy held the fan and I started it last night, and the clutch that's in there would let him hold the fan while the motor was running, as soon as he let go the fan caught up to speed with the motor??? Wouldn't that indicate that its good?

mac 'hate cooling issues' gyvr

[RichP]

WHAT !?!?!?!?! Do you also change fan belts with the engine running :) Wheres your sign :) :) :)
There is really no way to really test it and they do go, yours is like the classic symptom.

[martin]

Mac,

I agree with what RichP said, you have the classic signs of a failed fan clutch. I know it hard to believe since you see the fan moving but you are not getting full speed or full power out of that fan. Like I said before if the fan clutch is over 5 years old, just change it.

So keep in the back of your mind that you may need a new thermostat and radiator cap, even though you did not get to the red you may of damaged them. My radiator shop in st louis told me this 3 years ago and just yesterday I was talking ot my dealer mechanic while picking up a gas cap and he confirmed one time at 225F can damage a thermostat. If you see the needle not holding stead they you know the thermostat is damaged.

Jim the dealer mechanic told me after I mentioned the gas cap how people don't change thermostats, radiator caps, and gas caps. Would prevent alot of break downs buy changing them since they do wear out.

The only reason why I know this stuff is because I lived it with my 88 XJ. I have learned changing/replacing parts is what it takes to keep a XJ running. Time to cultivate a good relationship with the dealer parts guys. The parts guys know me so well they all say "hi" to me when I pass them in the hall way at the dealership. Also, depending on the guy who answers the phone I don't have to prepay for "special orders" just pay when I pick it up.

Martin

[macgyvr]

Originally posted by RichP
WHAT !?!?!?!?! Do you also change fan belts with the engine running :) Wheres your sign :) :) :)
There is really no way to really test it and they do go, yours is like the classic symptom.


Um, well we had drank some beer.... I didnt hold the fan... a buddy did...I started it...

Ok, I'll change the fan clutch cap and thermostat again.

On a trail rig is there anything wrong with a tstat under 195? like a 180 or 160? are there benefits? or should I stick with what the factory says to do?

mac 'drunk wrenching' gyvr

[Uglygreenxj]

I am experiencing cooling problems too. Last year I installed a three core radiator (for a manual), a high flow t-stat housing and t-stat, new hoses, a flowkooler water pump, a very large tranny cooler (no longer routed through radiator, new sensor in t-stat housing, new electric fan, and finally, a new fan clutch.

Now that its hot out again (I live near Phoenix) its running hot again. It runs about 200-210 on the highway, but in traffic or at a light, it IMMEDIATELY jumps up to 230- 235 or so.

Any suggestions? From reading the above, I gather I should replace the t-stat and the radiator cap but I hate to replace the clutch without knowing its bad they're not cheap and mines only a year old! I do remember not noticing any difference in cooling when I replaced it last year.

[Loose_Nuts_Enterprises]

Have your cap pressure tested, but may need the chemical flush.
Flush out the block both directions, flush the radiator, and the heater. I had to do mine separately. I think what did it for me was:
Take t-stat housing off
Take upper rad hose off of t-stat housing
insert garden hose in open end of rad hose
turn on water full blast and watch all the junk come out of the t-stat hole infront of block.

I did this after doing the chemical flush.

I also did the same with the heater.

Remove heater hoses from heater valve (hoses that come out of the firewall)
run water both directions through heater core.

Mine was partially plugged and Green and Brown stuff came out.
Cooling system with a cold and fever!

That seems to have taken care of my problems, just did this last night.

Dan

[Uglygreenxj]

I just picked up the stuff for the chemical flush the other day. I never thought to flush each component seperately like that. Sounds like a good idea. I usually just throw in my alternate heater hose setup with the inline Tee and go for it.

[Loose_Nuts_Enterprises]

If you do it semi regularly, you probably don't need to go through all the hassle that I did. I was just doing it every possible way to ensure I got it all. I was at my wit's end, feeling much better now, thank you.


Hope you get it all figured out!

Dan

[RichP]

Careful of those hoses going into the heater core, brake on off and you have real problems. If necessary use a sharp exacto knife to slice them loose. Don't pull, twist or yank hard on them.

[macgyvr]

where do i get the stuff for a chemical flush? I think I'm going to do that as well as I bet my cooling system has a ton of crap it in, i never thought about doing that

when i put the new to be used motor in three years ago i broke one of the ends of that heater valve, what a pain, i would becareful if that baby is stock cause it will be brittle, if i remember I got that valve at napa for a decent price if it does get broken.

I think I'll flush the system both ways replace all the hoses, tstat, cap and fan clutch here within the next week or two and report back.

mac 'flushed' gyvr

[Loose_Nuts_Enterprises]

You can get the chemical flush at any auto parts store. Prestone and Xerex makes it. Two varieties, 10 minute flush, and a super cleaner, that you put in and drive for like 3-6 hours over a couople of days. Then you get to flush with clean water all over again. Some say to use distilled water only in the cooling system to avoid calcium deposits and chlorine and what not.

HTH, Dan

[macgyvr]

well the only problem with that, is that part about driving 3-6 hours over a couple of days.... i dont do that, it sits in the garage....


oh and the flush deal that was done with the upper radiator hose through the tstat, is that done with the motor running?

i know its not like changing a belt....lol

mac 'heading out to the auto parts store' gyvr

[Loose_Nuts_Enterprises]

No, I did that with the engine off. I still have the super clean stuff in my cooling system. I only drive about 5-10 miles a day. I flush it out again this weekend.

Dan