My Renix is overheating! Please help me!!!

Hi all,

My new to me 1989 Jeep Cherokee Pioneer 5 speed has started to over heat and I don't know why. This jeep has been sitting for the past couple of months without being driven daily. I decided to start working on it today after the past couple of months of it just sitting in the drive way collecting dust and the horrible weather we have been having here in CT. All I have done to the Jeep to get it into this shape was to just fill it with gas and just drive it regularly on the street.

I have an idea as to why it started to over heat but the reasons I'm about to list just don't make sense as to why it would just start to overheat.

Here are the reasons:

1. I just filled it up with gas for the first time in months. (No idea why this would affect the Jeep with this overheating).

2. Maybe driving it after months of it sitting in the drive way maybe something knocked loose or something else.

3. I don't have any pedal brakes only the emergency hand brake (I used the emergency hand brake the entire time for the short time I had it on the road, Maybe that did something, but when it idled in the drive way it started to overheat.

I have been warned that when I purchased this jeep my friend told me that " Its a Renix engine with the infamous Renix closed cooling system it is bound to fail." Is this the infamous Renix closed cooling system failing on me or is this something else,

What are the options to fix this I was told by my friend that I could swap the cooling system of a Renix to something better than a Renix is this true? Also, How would I go about this? Is it hard? Like 1-10 how hard? Is it something I could do in a day or maybe a weekend with some help from my friends who are mechanics?

Another option is that my friend said to me is that I sell my 2000 Grand Cherokee Laredo WJ pocket the money, Buy a new XJ, Swap the old XJ 5 speed transmission to the new XJ if it is auto transmission, Lift the new XJ, and be done with it.

The only problem with that is if I do go the new XJ route I would have to make that my daily driver and not my beater Jeep, which I want. If I do go that route I would have to change my tire selection from an Mud Terrain to an All Terrain.

Please help me. I don't want to lose this Jeep, one of the last things my mother has given me.

Here is a list of things.

1. Check for leaks (radiator, water pump, thermostat housing, heater hoses, heater control valve, heater core, resovoir (aka turtle tank).
2.Check for blocked airflow across the radiator ( lots of bent fins, lots of bugs and grime build up from over the years), other coolers blocking air flow (the a/c condensors are notorious for blocking airflow so bad it causes overheating issues, make sure the efan works, make sure your fan clutch is good. Some people upgrade to the zj clutch, I hate my zj clutch so bad I'm going back to a xj fan clutch.
3. Check to see if the water pump is pumping (pull heater hose off of tube and turn Jeep on, if water starts to come out then the pump is pumping)
4. Spend the dollar on a tstat gasket, pull yours and check to see if its the correct temp (195) and check to see if it works. (put in 195 degree or hotter water and see if it moves.)
5. Pull your radiator out and rinse it out with the hose really well in and out both ends til you think its clean. While its out blow compressed air back through the fins the opposite way it blows in while driving. Also, blow air through any other coolers you have installed in front of the radiator.
6. If you need to buy a new radiator, buy one for a 91, 92, 93 etc. They are the radiator you need to convert to the open style system, even if you arn't ready to convert, get that radiator every time. Because it is not a hardcore jeep I dont believe in the need for any radiator other then a good quality stock replacement.
7. Make sure your temp sensor is working properly.
Im probably forgeting stuff, but its late. good luck.

Restruction said:

3. I don't have any pedal brakes only the emergency hand brake (I used the emergency hand brake the entire time for the short time I had it on the road.

Click to expand...

Uhm....WTF?!
Maybe your jeep is just telling you not to drive it til you have brakes? :wstupid:

more importantly, fix the brakes issue. being it is an 89 i bet you have the dreaded bendix antilock system. if so, do a search on swapping the system for a 95/96 duel diaphragm booster master cylinder. junk yard parts work fine in most cases. get the pedal assembly too. easy swap.

now for the cooling issue. the closed loop system is actually very good when working properly. some suggestions have been made all ready, one that i have found is the heater control valve has a VERY small hole allowing the coolant back into the bottle. if you do not see coolant flowing back into the bottle durring warm up, i am betting that tiny hole is clogged. it is a "T" fitting so the hole is hard to get to but can be done with a pick tool or something similar. i opened mine back up and the temp went down considerably. coolant system worked great and still is on my 89. but i broke the heater control valve doing other stuff and had to replace it with a new one. still a tiny hole and probably a bit smaller than what i did to my original one because the temp is now up about 5-10 degrees.
you will also want to flush out the heater core. i hooked up a garden hose to reverse flush mine and a few others and i was amazed how much brown gunk came out. afterwords both the heater and cooling system worked a million times better.

I'm sorry for bring up such an old thread but I thought that I had fixed my problem. Well, I thought that I fixed my problem I noticed that I was low on coolant so I filled up the reservoir tank to the full line. I drove it around for about a half hour and the temperature was doing good it held steady at the middle temperature. But when I got out to check the reservoir I noticed a smell of burning coolant it was not strong but it was there. I thought nothing of it and I just left it in the drive way. Come the next morning I went out to check the coolant to see if it was still there. Not to any surprise there was no coolant in the reservoir. So, I'm burning coolant somewhere but I don't know where, there was no spot on the driveway so IDK where it went.

My friend once told me that I can do a full Renix swap. How would I go about doing this? Is it hard to do? My friends are all mechanics and one is an avid Jeep enthusiast who said he would help me but only if I find out what I would need to do.

Please help.

First.., please answer as to whether, or not, you have followed the good advice you have already been given thus far. In other words a full blow-by-blow listing of exactly just what you did.., " I thought that I had fixed my problem. Well, I thought that I fixed my problem".

Second.., did you park with the nose of the vehicle down hill, or jack up, and jack-stand the rear end so as to get the rear of the engine up higher than the front? Did you at that point open up, (remove), coolant temperature sender? Did you then start the engine, and while in there.., turn on the heat control to max? After a short period of time, i.e., allowing the engine to warm up, did you closely monitor the fluid level in the tank, (adding anti-freeze/distilled water mix as required)? If you did thusly, at some point in time, the air bubbles in the passageways would all be removed via that sender port, and as such, when a copious, obvious burbing of fluid becomes instead; a steady flowing stream of fluid visibly pouring out.., is exactly the moment one replaces that sender. You have just evacuated most nearly all entrapped air in the system. Check to make sure you have managed to maintain the fluid level in the tank to the top level of that vertical pipe in the tank.

Thirdly, have you inspected your tail pipe for copious amounts of water, (wet/carbon)? The ground below it after idling for awhile? Or was the pipe dry?

Is your oil level normal? Water on the dip stick? Brownish oil on the dip stick after idling?

I stop now.

Perhaps there is a vacuum leak causing a lean condition and lack of booster?

My first thought was a busted vacuum booster.