overheating

[valleytroll]

Have a pretty much stock 89 laredo 4.0 What I have changed is a Rusty's 4.5 lift,flowmaster, and yokahama geolander mt 31's my problem is that while driving on highway it will stay cool and then start getting hot, have asked around here in central ca. All the radiator shops want to convert to a 93 or newer radiator, I personally thout there might be some blockage due to the age. it has right at 100k miles from what I gather not the best care from what I saw when I replaced the rear main seal. Any thoughts would be appriciated.
Valleytroll

[Yucca-Man]

You already know the answer - the radiator needs replacing, especially if it's the original. They were marginal to the task 14 years ago, and it's probably all sorts of clogged.

There have been a lot of threads about this recently, I've collected a number of my thoughts and experiences with an overheating 89 XJ at http://www.yuccaman.com/jeep/cooling.html

[churky89]

You can use a open style rad from a 91'+heater valve also for a 91'.Not that hard to do.Make sure you chk the water pump also if you have any doubts about the water pump chang it out.
New upper and lower rad hoses
New htr hoses.
BUT BEFORE YOU DO ANYTHING BACKFLUSH THE HELL OUT OF THE ENGINE BLOCK!!!!!!!!!!!!!!!!!

[BrianG]

well how hot is hot? 210 is normal.


if you do end up replacing the radiator, definetly switch to the open cooling system..

[Eagle]

IMHO any original radiator that age is overdue to be replaced. You can change over to the "open" style radiator if you wish, but it does NOT in any way increase the cooling capacity. What it does is leave you the problem of how to control the auxiliary fan. If you run a search you will find innumerable threads on this, and innumerable solutions that mostly don't work.

There is really no valid reason not to replace your radiator with a direct-fit "closed" style replacement. Ask the shops who want to push the conversion how they plan to control the auxiliary fan after they put in a radiator with no bung for the sensor.

[TLange]

I have a '91 with an open system. I just replaced the radiator two months ago. The replacement radiator was purchased locally from a radiator shop. It does have a bung for the older style aux fan switch. This bung is located on the driver's side tank between the transmission lines. Of coarse for my '91 the bung is plugged. I don't know what brand the radiator is because it came in a plain white box. It's an all metal two row and looks a lot like a Modine.

[valleytroll]

Well, went for the gdi 3 row radiator, new w/pump, tstat, all new hoses will see how it does towing our canvus hunting mansion to Big Meadow to kill Bambi will let you all know. realy appreciate the input.
Valleytroll

[Backdraft]

Eagle, I swapped over to the "open cooling" system and knew it wouldnt help cool my jeep any better than a properly operating closed system. My reason for switching over was for the ease of burping the air outta the system. After doing the conversion, my neddle never sees over 210 and it was a piece of cake to fill and purge, very unlike the closed system which would usually take me a couple days to get it right.

my useless $.02


Mike

[woody]

triggers the dashboard gage?

[GSequoia]

Originally posted by woody
triggers the dashboard gage?

THe one in the rear of the head, just has one wire off'a it.

Also, at some point I'm going to find a thermostatic switch for that aux fan, I plan to have it screw into a pre-existing hole in the '91+ thermostat housing. I will let everybody know where to get it when I find it. I figure one that goes off around 205*?

Sequoia

[valleytroll]

Backdraft it was a pain the butt to blled the air, found the best way was to almost stand the thing on its nose seems o.k. now but time will tell.
Valleytroll

[8Mud]

I´ve found vigorously squeezing the top radiator hose with two hands, until it makes a sound like a demented suction pump, with the motor hot, works for me. To be repeated at intervals, until the coolant level in the resivoir stops falling.
The last OEM thermostat I bought, had an extra little ball check valve at the top of the large valve, guess it´s to help with burping the system.
My fan clutch is getting tired, I switched over to the newer style aux fan, with more vains, cools it back down jiffy quick. When it heats up at idle.
I´ve got a fan clutch out of a 88 Chev K-1500 V-8, that looks like a fit, but a bit larger in diameter. Next project after the exhaust.

[brian]

I think the lower hose has a lot to do with this problem. The factory has a spring inside to stop it from collapsing but parts stores ones don't. And this would help at higher RPM'S on the highway.

[MacGowan-XJ]

Why don't you guys just convert your aux. fan to run off a switch?
I have done this on my Cherokee and it works like a charm. It's great for offroad use as well, as you can have it off or on depending on the conditions (IE ON at all times when crawling, or OFF when going through water).

[four_shot]

I'm lucky...I've got an '86 with a 2.8L...lol. I don't have to worry about burping the cooling system. Even if I did, I have one of those "airlift" type cooling system evacuators. It draws the cooling system down to around 27" Hg, and then lets atmospheric pressure push coolant in... no air = no air bubbles! A real neat investment if you've got shop air or a strong compressor. Unfortunately, the only place I've seen them are on the tool trucks