zebvance

I have a 1988 renix mj with a 4.0, 103K with the closed loop system that was from Canada. It started to over heat on my in the city a month or so ago in the peak of summer about a month ago. I live in south texas so temps get up to 100-110 all summer. I wanted to eliminate all possibilities so I started to replace the WHOLE cooling system.

One thing to mention. This truck did not come with ac from the factory and it did not come with the Electric fan from the factory also.


Items Freshly installed:

New zj Fan Clutch
New CFS 3 row radiator
new Flow Kooler water pump
New High flow thermostat
New themostat housing
New upper and lower radiator hoses
New Fan Shroud
New Serp Belt.
New sealed Overflow Tank
New coolant

I got it all hooked up and drove it for a bout 20 miles on the highway and a little in town and it did fine. Then I parked it and let it Idle. And this is what it did.

Outside Temperature : 75 degrees Fahrenheit
Time : 8:45 PM

Dont have a picture of when I parked it but it was sitting at the normal mark.


Time : 9:05 pm
Time elapsed : 20 mins


Time: 9:15 pm
Time elapsed : 30 mins


Time : 9:25 pm
Time elapsed : 40 mins


Time : 9:35 pm
Time elapsed : 50 mins


Time : 9:45 pm
Time elapsed : 60 mins


I will say the temps do not climb nearly as fast as it did before I replaced everything but then again it was around 85-90 degrees when I did.

Let me also note that like I said the truck was made in Canada that's why the temperatures are in Celsius. However I know the truck has been in Texas for at leased the last 10 years.

Lastly, The Truck does not show any signs of head gasket failure. exhaust is VERY clean, no smoke, no water or coolant coming out of it, and it does not burn it.


Please help me and tell me what to do now!!!!!

falcon

Seeing how I am dealing with putting my cooling system back together maybe I can offer you some ideas... (don't yell at me I know some of these you have probably tried)

First things first... Do you have a fan shroud installed? My Renix need the fan shroud to move enough air on idle in the hot days sitting still. Something to bridge the gap from the radiator to pull more air though. Sometimes a extra fan will help, but usually the AC fan does not come on unless you have installed a switch or aftermarket thermostat (if you are not running the AC) In mine anyway.

Simplest thing to check, do you have a good seal on your radiator overflow bottle? If its not a tight seal on that little cheap cap, the coolant will boil and it will overheat. My NEW bottle had a leaky cap, and I replaced it for a 3rd time with a tight fitting cap. You could hear a slight hiss from the cap when it was warm.

I'd look carefully for any leaks, with the engine warm and cold, especially around the fittings and clamps.
There are no leaks around the hoses, radiator, heater core? I always seem to find a leaky fitting somewhere every time I mess with a cooling system. On mine is the hoses from the coolant bottle, and I am getting some new ones from Jeep this time to ensure that they fit. On the Ranger it was a thermostat gasket that is notorious for leaking. On a Supra we did we replaced the radiator after some very minor damage to the fitting on the lower portion when trying to remove the caked on 19 year old hose.

Is the upper hose from the radiator to the thermostat warm after the thermostat has opened up? You should feel a "flow" on the hose and it should be hot. If there is no flow your thermostat didn't open for what ever reason. (after warm up of course)

Here is a silly one, on the lower radiator hose on my 90 there is a spring in the hose to hold the hose open from "suction" on the return back into the block. Did you install that in the new hose if you replaced it?

Maybe you have a blocked radiator core or defective radiator? Easy to check it in various spots to see if there are any cool spots (with hand or with an infrared thermometer maybe). Should be consistent temps though out the radiator with no cold spots. If you have a cold spot (also a good idea to check for leaks) It may be time for a warranty. Not really expecting this but stranger things have happened to me especially on fragile shipped items.

Check both temp sensors, there are two one for the gauge and one for the engine in my Renix. those could also be a failure point as well IE providing you or your Jeep with false data.

Open up the heater core by putting your heater on full blast yes with the fan on, see if there is any difference in cooling. That is essentially a 2nd radiator, you can see if it makes any difference. Sometime you can compensate for a weak cooling system by exchanging more heat temporarily. Also helps to remove air pockets from the system.

How long have you run the Jeep since its been filled? Maybe it has not been "belched" and there is an air pocket in your system, run it for a few days and keep topping it off. I have read that a faulty temp sensor can also cause it not to fill properly.

Maybe you need to flush it again and replace any other worn out hoses?

If the sensors are OK, and you are sure that coolant is in every nook and cranny... then perhaps you have a faulty head gasket. Mine was leaking outside of the block, with out over heating. Besides being a visible leak at the gasket it also ran warmer and had a slightly rough idle. Testing it with a cheep kit form the auto parts store confirmed that the gasket was bad and oil had leaked into my coolant. A pressure test also indicated that there was a small leak on my 3 and 4 cyl which was lower compression then the rest. After installing a new gasket it runs much cooler and has less hesitation and rough idle. Based on my 30 year old Suzuki and my 22 year old jeep the decomposition of my head gaskets in these machines warranted a replacement on them recently it may just be time. They are after all just gaskets.

You may have air in there too...
Now some one will come and post, oh its this.... One line it will be solved

Should keep you busy for a bit!

PS there are lots of Renix threads on overheating 'round here..

zebvance

UPDATE: I took the truck today to the scrap yard to drop off a lot of junk to get some cash to fix the truck. I took it to a shop and are having them do a pressure test and check the head. they are also goin to look at a bad leak that has developed around the slip yolk shaft. And one more thing. While getting out on the high way I floored it in 1st gear and it seemed to bog/hesitate, the it opened up and took off. any ideas? it only doest it in first when you floor it from a stop. BTW it is a automatic.

zebvance

UPDATE: Just talked to the shop and they said they were able to duplicate the problem. Then the did a pressure test on the head gasket and they said they had no problems with that and the head gasket was good. Then the put a little 10 inch fan in place of were the factory electric fan was and said it never got over 205. The demmed the problem being from me mounting the tranny cooler in front of the radiator on the side that the mechanical fan is and my bumper and winch and lights is covering up to much of the surface area of the radiotor and blocking air flow. so looks like I'm installing the datsun 240z louvers and hooking up my electric fan and hoping that it performs well enough trail to not overheat and not just keep the temps under control on the road.

zebvance

Very happy that the head gasket is still good!

cruiser54

Try this. Replace the coolant bottle cap with one from Napa. 703-1396.

zebvance

I have a new overflow tank and cap on it. Its just the dorman brand though..

cruiser54

The Dorman are crap-caps from China. Try the Napa one from a Volvo.

zebvance

Will do. Just looked it up and it was only 7 bucks so it cant hurt right?

cruiser54

Can't hurt and could help for $7.