over heating 101

Need a lot of help on the over heating subject, I did look for some answers on this forum, but will apreciate more opinions and recomedations.
xj is a '89 limited 4x4, auto. 99.9 % stock (flow master).
238k on it. no major rapairs done, replace the valve cover seal (hasn't every body?)
No water or oil leaks, just add 1/4 of oil Between oil changes to keep it level.

It almost, over heated, going to el centro ca. going up the sierra on the mexican side of the border, out side temp. was over the 90's had to turn off the AC, did came down but still at one time it almost reached the red zone. didn't need to pull over just drove a little slower 55-60 mph. water bottle with coolant at a it's normal level, no visible leaks from the bottle, cap or hosses.
the normal running temp. is about 190 hyw. 210 cty.

Repairs done:

Water pump and belt were replaced abut 500 miles ago (xj only used on the weekends).

Using coolant since bougth.

It has the OEM overflow system, did replace the bottle and cap less than a year ago, bought the "improved design" (on Ebay).

The radiator is in excelent condition, removed and professionaly cleaned 1 year ago, no deterioration found.

this is the first time that this has happened since i got it. (210K when bougth, will be 3 year next sep)

in 2005 drove to los cabos (1000 miles from the border) in July with the family and pulling a small trailer (4x6) about 400 pounds, mostly camping gear, never reached 220 and had the AC working most of the time. (average temp down there is 110-120 F) in the summer.

does any one has some sort of check list that I can follow and be certain that I'm not missing anything determining the probable cause of the faulire?

like:
fan cluth (read about the fan cluth, how I do I verify it's working 100%)
belt (tension belt was imporant)
water pump.
flushing the engine.
etc.

were planning some vacation time next month, don't want to be stranded with a 4 year old and wife in the arizona desert (or any desert!)

I promisse that I will try and follow every recomendation to the nose that gets posted.

Just for the record.
I live in Ensenada Baja, Mexico, 75 miles south from the US border with SD CA. we have down here: autozone, napa, etc. I can get mostly every normal or stock parts, for special stuff I can go and get it in the states if needed.
thanks...
Rick

do u have an auxilary electric fan? and if u do have u check ti see if it is still working?

see if you can squeeze the lower radiator hose. There is supposed to be a spring inside to keep it from collapsing. If you can squeeze it, replace the spring or get a new hose with a spring in it.

yes, and works normal, when you turn the AC on, and when the engine is getting hot.... I notice that it hasn't the plastic fan protector (shroud?) could this be another issue to look in to?
thanks

Ok. thanks. I'll verify this....

If you don't have a fan shroud you need to get one. The fan shroud allows the fan to pull air directly through the radiator. With out one the air is being pulled from everywhere but through the radiator. It is very critical.

fan clutch shouldn't have much of an effect at highway speeds, neither should the aux fan. At highway speeds you should have more than enough flow across the radiator just from forward motion.
I would look into a stuck or sticking thermostat, it may not be opening all the way.
It sounds to me like you've got a coolant flow problem, with that much air running over the rad@ highway speeds I doubt it's an airflow problem, unless your radiator is obstructed.

I've posted this several times in other threads and become bored posting it, but here it goes again anyway.

I pulled off my clutch fan this winter to see if the performance gains alone were worth changing to an e-fan. This way I wouldn't run the risk of overheating while I experimented, etc. Long story short, I'm still running with JUST the aux/AC fan on the one side and nothing on the other, outside temps are now in the 90's and I still don't get so hot that the AC fan can't keep up. I consider this a very healthy cooling system, but it has taken some time and work. I have a new 16" fan sitting at home, maybe this weekend I'll buy a relay, shroud, etc and install it, I'm not in a huge hurry, I'd kinda like to see just how much the system can take without the fan... I have also rasied the back of my hood 1/2" to get a little better air flow, seemed to help a little without being too noticeable. I may go to a better vent someday.

Anyway, you say the radiator has been cleaned, etc. I'd do it again. Take the lower radiator hose off and drain as much out of the system as you can, refill with as much vinegar as you can get into it and drive it for several days, then flush the system as aggressively as you can. You will get all kinds of chunks, sludge and scale off the cylinder walls, head and radiator passages. When you refill the system use a mix of about 75% distilled water and 25% antifreeze. Keep a really close eye on your overflow bottle for several weeks, it will continue to collect the sludge from the cooling system, and you can just remove the bottle and wash out the sludge in 10 minutes to keep the system crud-free. I did the vinegar trick months ago and still get a little bit of sludge over the course of 2-3 weeks.

I wouldn't use a thremostat lower than 185*, and to stick with the 190* is best, but when I replaced mine last the guy accicently gave me a 165* and I didn't catch it until I noticed it wouldn't heat up. This actually gives me a little more time before I get hot while sitting in traffic simply because I start 30* cooler, but it's not good overall and it gets changed soon. Fuel economy is slightly down with the cooler thermostat and I really dont' see any reason to run it.

I will add one more thing, radiators do deteriorate, the copper or aluminum fins corrode and stop transferring heat. The rad shop that explained it to me called it rot, mostly on copper core, the fins get soft. while the flow might be good if the fins are rottted you won't get good heat transfer. He showed me a trick on my old radiator and the new one that involved running my thumb backwards so the thumb nail would depress the fins a bit, if they stays depressed the core was rotten, if they sprang back up they were good..

Just replaced my radiator yesterday. Fixed my cooling problems. Do you actually know how old your radiator is? It's not a very expensive fix (about $110 for a CSF 2 row) if it is the case. In my case, my radiator was totally shot. I would drain my coolant from the plug and I would get like .5 gallons of fluid. Things work great now and when I drain it from the plug, all the coolant comes out.

Hey guys, speaking of fan clutches, how much resistance should be in it when it's up to temp? I've got a 95 that like to get into the 230 range when I'm in slow traffic (which is a lot) and I have some resistance on the clutch when I'm up to temp, but it still spins free for 5 or 10 seconds when I shut the motor off.

In my case I cancelled the fan clutch and bolted the fan to the engine it helps cooling in Egypt but I lose performance, Fuel economy and sound like a 747 in reverse thrust

SCW, while on the flushing subject. what's the proper procedure to do the flush and refill for the return bottle system. when the water pump was replaced, I was told that this particular system is filled different from the "traditional" way, it has to be purge?
thanks

In Brazil, there´s no XJ that goes off-road and does not boil. In my case it´s a '98 Sport, I have changed the radiator with one custom made with one more' cooling cell', have changed the pump with a flow kool, have changed the thermostat with a 185 and changed the hoses and I still get it to boil in the overflow bottle.

The problem I have is that at low speeds off-road it boils while on-road it is ok, the air temperatures are between 64F and 113F.


My next steps are: taking out the thermostat, keeping the fan that has a clutch always on and changing the rad cap with one that holds up to 24 psi.

Is there anything else to be done?

UN-limited'89 said:

SCW, while on the flushing subject. what's the proper procedure to do the flush and refill for the return bottle system. when the water pump was replaced, I was told that this particular system is filled different from the "traditional" way, it has to be purge?
thanks

Click to expand...

On your closed system you will have to "burp" the system to get all the air out of the block/head every time you flush, drain or backflush. There is a lot of info around on ways to do that, I have the open system so I just yank the bottle out and stick a garden hose down it to wash out the settled crud. Same concept on yours though, the bottle will act like a basin where the solids will settle over time so just keep an eye on it and when you see some, take it out and wash it then re-burp the system. You might want to drill a hole in the thermostat to make it easier, look up 5-90's method on a search. I have read it but didn't pay too much attention since I don't have the closed system. You can also burp the system by opening the temp sender and letting the air bleed out, then closing it up when the coolant starts coming out. I've never done it though-

It's still not a difficult thing by any means, maybe take a few minutes longer is all.