Overheating question

[stew1978]

A mate of mine recently bought a Jeep Cherokee, a 1994 model I think.

Anyway 2 days after having the car serviced we went for a drive on Stockton to see how it goes in the sand. It went OK until it started to over heat.

Now both of us have very little mechanical knowledge but we lifted to bonnet anyway to see if anything obvious was wrong. When we lifted the bonnet we noticed that a large amount of coolant was being pushed out the overflow pipe connected to the coolant reservoir. It appeared to be boiling. So much so that when the car had cooled and we opened the radiator it was almost empty.

He has taken the car up to Watagans before without this problem occuring and it has not happend since while driving on road.

What could cause this and how can he avoid it in the future. I've heard Jeeps can overheat on sand but this seemed to be extreme.

[wolfe 503]

Aaah, the perenial overheating question! Honestly the search button is your friend.
http://www.ausjeepoffroad.com/forum/index.php?

http://www.naxja.org/forum/index.php

http://www.pirate4x4.com/forum/forumdisplay.php?f=67

http://www.go.jeep-xj.info/

Basically, yes a lot of jeeps will overheat on sand. Its like driving up hill all the time,as your pushing the sand in front of your tyres.
You could check viscous fan coupler, put vent in hood. You could also lift rear of hood with washers. The xxxpedition people told me they replaced their radiator with an aluminium one from the states and they swear by it. Wooders knows the brand and could order it if you ask nicely.

[Richo GU]

Anyway 2 days after having the car serviced we went for a drive on Stockton to see how it goes in the sand. It went OK until it started to over heat.

Stockton seems to be the place for jeep's to overheat, surley its known problem, as we have witnessed 2 jeeps burn to a rusted melted heep during our visits up there over the last 18 months. The second one made it to 4WD monthly the poor guy was on a club outing and the whole of stockton beach gathered at the sygna to watch as everyone pulled out there fire extinguishers to try and put it out. 45 minutes is all it took and she was gone. The jeep a great 4WD but there got to be a known problem sorta like he ZD30 3 litre motor out of the early GU's as they just blew up come 80000kms. Car manufacturers really do have a lot to answer for sometimes as people invest dollars into there cars. Most of the early ZD30 motors have been replaced or modified with much debate still going on as to why, but still no exact known cause, mmmmmm

[sir_camel]

The jeeps that burned were KJ's (the newer Cherokees) and are completly different issues to the one mentioend in this thread.

I believe XJ's were originally designed (back in 85 or there abouts) with a 4cyl engine. Then when the 4.0 came out they decided to shoe horn it in there and it just fit. Hence the 4.0 fills up every last space of the engine bay meaning it gets pretty warm in there. When working hard on sand it gets that little bit hotter as in any 4wd, sand seems to require a little bit more from the truck. I have the same motor in my TJ but it doesnt overheat on sand as it seems to be a much better cooling system (and there is MUCH more space under the hood). This issue discussed here is not about jeeps catching fire though...

[PK]

Basically, as sir camel says, XJ's do run hot under the bonnet, which is why a good clean radiator, with good clean coolant is a necessity. A lot of people also make the mistake of not using low range when they should (not saying that is the case here) and making the engine labour, rather than keeping the engine in its premium torque band in low range.

[Wooders]

Yup Ill bet they were in hugh rnge not low range which makes a huge difference on Stockton in the XJ's

[stew1978]

Was running in low range that day and had a clean radiator with new coolant. As I said it was only serviced a few days before.

His mechanic has offered to check the cooling system to see if there are any faults. Any advice on what he should be looking for?

[Captain Trenchard]

Just to add further fuel and range to this question I am an owner of a 99 WJ Grand Cherokee Laredo.

AS a mechanic I checked everything over before I purchased it including carrying out coolant and system pressure tests about 8 weeks ago.

Post purchase I changed out the fluid and retested the system. No faults were found.

Wife thought it would be great to hit the beach and living in newcastle selected Stockton as our beach of choice. Let the tyres down to 16 PSI all round and selected low range and 30 minutes into our journey down the golden sand temperature hits 120 degrees C. When in a cloud of steam I pulled up the truck. Opened the bonnet thinking hose only to find a piece of the plastic radiator tank missing.

Consequently I am now replacing the radiator, thermostat & water pump in a bid to eliminate any further problems.

Even with my trade knowledge and 4*4 experience gained through courses and work I am still at a loss to answer why this happened.
The beach recovery agent for stockton did say this was a common cause of his employment on weekends.

Cheers Captain Trenchard

[just a tj]

My TJ has been getting hot on Rainbow Beach and wheelin' in 4Low, finally pulled the water pump out and was surprised at how much of the casing was missing due to corrosion. the impeller was fine but had 40 % of the casing missing behind it. No wonder it got hot, would have been cavitating horribly I guess. New pump and all is fine. Pays to check these things occasionally.

[FireTruck]

start with the easy stuff... new radiator cap, check thermostat. If you are getting a kind of a dieseling sound (like a whiring sound) its probably the water pump.

Then have the cooling system pressure tested... viscous coupling on the fan maybe. It's easy to put some vents in the hood too for some m ore air flow.

Good luck - it's common to see Jeep's overheating, and not just on the sand.

S.

[Captain Trenchard]

Just an aside I have now replaced the radiator, waterpump and thermostat in my 99 WJ 4.0lt. It now runs at about 82 degrees C on the open road but continues to get up near a 100 when idling in traffic.
I haven't been allowed to return to the beach but I must say that this 4B now runs a lot cooler than it has ever run since i bought it.

Still can't get the thermo to cut in however can anyone tell me where the temp sensor for this is located.

Cheers Capt T

[AussieCJ7]

Just an aside I have now replaced the radiator, waterpump and thermostat in my 99 WJ 4.0lt. It now runs at about 82 degrees C on the open road but continues to get up near a 100 when idling in traffic.
I haven't been allowed to return to the beach but I must say that this 4B now runs a lot cooler than it has ever run since i bought it.

Still can't get the thermo to cut in however can anyone tell me where the temp sensor for this is located.

Cheers Capt T

you better read your workshop manual again !! the 4.0l operating temp is around 100deg !!! less than about 92 deg (stock thermo ??) and your computer will force into open loop mode and fuel economy will suck even more than normal Jeep 4.0L do NOT like cooler thermo's

[AussieCJ7]

btw temp sensor for guages is normally on the back of the block on the passenger side for a 4.0L temp sensor for the computer is in the thermo housing

[Captain Trenchard]

btw temp sensor for guages is normally on the back of the block on the passenger side for a 4.0L temp sensor for the computer is in the thermo housing

Thanks Aussie I will double check tomorrow what the Jeep is running at with a seperate temp gauge, but I am sure when I purchased these parts that the book gave me 82 degrees C for the thermostat.

As for fuel econom,y I recently took the family to grafton from newcastle[wife & 2 kIDS + BOX TRAILER] and made it point to point with a 1/4 tank to spare so far there has been no indication that the Jeep is running out of sorts.

Will check for thermo sensor tomorrow as well and see if i can get the thermo to cut in as it still reaches over 100 when in traffic at low speed.

Cheers and thanks again for the info and advice Aussie

Capt T