Ok, please enlighten me with this overheating issue lol.

[thamotivatedcouple]

Hello! My girlfriend has a 1994 Grand Cherokee Laredo 4.0 jeep, and has had several problems with it. I have done my best at what I was given to get it up and running, and have had several questions along the way. I am now trying to reach out to other owners, as I learned with my Subaru, sometimes the best advice and help you can get, is with fellow owners. I will give you all the knowledge that I have, and ask that any and all advice you have, please clue me in. it starts like this...

A few years ago, she was having some transmission problems. She took it to a mechanic, who just added atf fluid, and had it working for a little bit, but soon after the transmission "blew up" on her. From what she told me, is that the lines to the transmission cooler had been chewed up and they had to replace them and the transmission. A few months later, the same thing occurred. The shop replaced the transmission out of warranty, and the lines. The problem was the motor mounts were broken, and the lines got caught into the motor mounts (how, I don't know, lol) and were "chewed" up by that. She had the motor mounts replaced, the transmission replaced, and the lines replaced. Shortly after, the radiator was not working as advertised. She had the radiator replaced, and it worked fine. approximately 7 months ago, the radiator had some sort of milky "goo" in it. She took it to a shop who looked at it, and said it had to be flushed. They 'supposedly' flushed it a few times, then said that she needed a new motor. She said that they had said that the motor was cracked, the head was rusted, and that the head gasket was blown. They wanted her to pay 4500 for a new Jasper motor. She did not have the money for that and let it sit for a 5 months or so. When she started explaining it to me, I told her that I wanted to look into it and see what the problem was, and if it was something I could fix. I told her that I could find either a new motor (rebuild or not) for a decent price, and all I would charge her was a hug and a kiss for installation.
As I started to look into it, the radiator and cooling lines had some sort of Yellowish 'snot' inside it. I have never seen that color of 'snot' in a radiator before. I began to pull stuff off the motor to look at the head myself and the gasket myself, when I realized, the bolts had not been touched by a wrench in forever. I began to look heavily into the cooling system and found that the whole system was clogged with this Yellowish snot looking stuff. When pulled the thermostat housing off, there was no thermostat installed, and the gasket was worn down very heavily. I have seen blown head gaskets and worked on many a motor with that problem. The coloring of the goo was not anything I had seen before. Plus, the motor oil was in perfect condition (aside from the sludge that is associated with a vehicle that has over 200,000 miles on it).

There were no signs of a blown head gasket at all, at least from my experience, and no signs of any sort of issue. I bolted the car back up and decided to get it started to see what exactly it was doing. I got the car started, and it runs great. No knocking, no dinging, nothing. The motor runs great, but is overheating. I flushed the goo out as best as I can, and will get another cooling system cleaner a little bit later to clean out the residue as best as I can. I began reading more forums about the overheating problem. The vehicle has the belt run fan, and the fan clutch needed to be replaced. I have replaced the fan clutch, but it still overheats. Before I dump any more money into this, I would like to hear am I on the right track? does anybody know what the heck that snot was? There are no apparent leaks in the cooling system that I can see or find. The transmission fluid and oil both seem perfect and no signs of any head gasket issue to where the oil and antifreeze mix. kind of confused and would like some insight. Thank you in advance for any and all help. She loves this jeep and wants to keep it until the zombies come (they cant come soon enough, lol).

[Brasscatz]

that is some weird looking goo... I have no clue what it is, unless it's some sort of "stop leak" stuff for cooling systems. Yes, I think you're on the right track. Make sure it gets cleaned out VERY good, replace items that could have been gummed up like, coolant temp sensor, etc. Make sure heater core is fully flushed out (that's probably a big one because all the little tubes could be very clogged) radiator (might have to take it to a radiator shop to clean the whole thing out) water pump should be ok by just cleaning off the fins, but make sure it spins well and the fins don't have damage.

[Brasscatz]

You might have to go through the cleaning and flush process several times to get most of it out too...

[thamotivatedcouple]

sweet! looks like snot doesn't it? I have seen some crazy crap before, but I think this takes the cake. She did say they tried to clean it up, maybe with that stop leak stuff. I will clean it out over the next few days and go from there. thanks!

[Brasscatz]

Cool. Please don't forget about us.... come back with the results and let us know!

[thamotivatedcouple]

I plan to. This site is very well put together. Plus the amount of information I am finding is awesome. You responded right away, and I thank you for that.

[XJ Wheeler]

Never seen anything like that either. But my mind goes like this... The shop "flushes" it and then says "$4,500 please"! And there's this unexplainable stuff inside the cooling system. Which shoulda been cleared out if they really flushed it.

Now on to fixing this. What's the characteristics of its overheating? What speeds... how long to get to what temps... etc?

Sent via messenger pigeon - i talk, he types.

[Brasscatz]

I plan to. This site is very well put together. Plus the amount of information I am finding is awesome. You responded right away, and I thank you for that.

It's what we're here for buddy

[thamotivatedcouple]

I haven't driven it for an extended period of time yet. I have only been on the 'job' for two days now. when I turn it on, it heats up and gets past the 260 point in approximately 5-10 minutes. I plan to drive it around the neighborhood after rush hour traffic. I will let everyone know how it turns out after that drive.

[nickyg]

It looks like you feed your Jeep peanut butter. (They perfer crunchy over creamy). Did it boil over or did the gauge just go high. I'm wondering if all that goop fracked up the sensors.

[XJ Wheeler]

Yes, confirm the gauge is right. An infrared thermometer comes in handy here. If in fact its true that is quite a fast time to overheat that much.

Sent via messenger pigeon - i talk, he types.

[thamotivatedcouple]

that's where I messed up... I thought it said creamy... lol... to be honest, I think the jeep hates me now, lol... I might replace all the sensors as well. I did have to clean it off of the switch on the thermostat housing... lets see how it drives tonight

[Mudderoy]

Hello! My girlfriend has a 1994 Grand Cherokee Laredo 4.0 jeep, and has had several problems with it. I have done my best at what I was given to get it up and running, and have had several questions along the way. I am now trying to reach out to other owners, as I learned with my Subaru, sometimes the best advice and help you can get, is with fellow owners. I will give you all the knowledge that I have, and ask that any and all advice you have, please clue me in. it starts like this...

A few years ago, she was having some transmission problems. She took it to a mechanic, who just added atf fluid, and had it working for a little bit, but soon after the transmission "blew up" on her. From what she told me, is that the lines to the transmission cooler had been chewed up and they had to replace them and the transmission. A few months later, the same thing occurred. The shop replaced the transmission out of warranty, and the lines. The problem was the motor mounts were broken, and the lines got caught into the motor mounts (how, I don't know, lol) and were "chewed" up by that. She had the motor mounts replaced, the transmission replaced, and the lines replaced. Shortly after, the radiator was not working as advertised. She had the radiator replaced, and it worked fine. approximately 7 months ago, the radiator had some sort of milky "goo" in it. She took it to a shop who looked at it, and said it had to be flushed. They 'supposedly' flushed it a few times, then said that she needed a new motor. She said that they had said that the motor was cracked, the head was rusted, and that the head gasket was blown. They wanted her to pay 4500 for a new Jasper motor. She did not have the money for that and let it sit for a 5 months or so. When she started explaining it to me, I told her that I wanted to look into it and see what the problem was, and if it was something I could fix. I told her that I could find either a new motor (rebuild or not) for a decent price, and all I would charge her was a hug and a kiss for installation.
As I started to look into it, the radiator and cooling lines had some sort of Yellowish 'snot' inside it. I have never seen that color of 'snot' in a radiator before. I began to pull stuff off the motor to look at the head myself and the gasket myself, when I realized, the bolts had not been touched by a wrench in forever. I began to look heavily into the cooling system and found that the whole system was clogged with this Yellowish snot looking stuff. When pulled the thermostat housing off, there was no thermostat installed, and the gasket was worn down very heavily. I have seen blown head gaskets and worked on many a motor with that problem. The coloring of the goo was not anything I had seen before. Plus, the motor oil was in perfect condition (aside from the sludge that is associated with a vehicle that has over 200,000 miles on it).

There were no signs of a blown head gasket at all, at least from my experience, and no signs of any sort of issue. I bolted the car back up and decided to get it started to see what exactly it was doing. I got the car started, and it runs great. No knocking, no dinging, nothing. The motor runs great, but is overheating. I flushed the goo out as best as I can, and will get another cooling system cleaner a little bit later to clean out the residue as best as I can. I began reading more forums about the overheating problem. The vehicle has the belt run fan, and the fan clutch needed to be replaced. I have replaced the fan clutch, but it still overheats. Before I dump any more money into this, I would like to hear am I on the right track? does anybody know what the heck that snot was? There are no apparent leaks in the cooling system that I can see or find. The transmission fluid and oil both seem perfect and no signs of any head gasket issue to where the oil and antifreeze mix. kind of confused and would like some insight. Thank you in advance for any and all help. She loves this jeep and wants to keep it until the zombies come (they cant come soon enough, lol).

I've very concerned about this "snot" The coolant system is under a lot of pressure where as the oil system is not. With a cracked head or block I think it would be more likely that there would be coolant in the oil, the milky substance that most people describe. I've read your post a couple of times, but I don't recall if you said how the oil looked.

Personally I wouldn't drive it very much until you figure out where this stuff is coming from.

One thing that comes to mind is a leak inside the radiator where the transmission fluid is mixing with the coolant, but then I would expect there to be coolant in the transmission.

A cracked head probably wouldn't make the 4.0l run bad, it would just over heat. Eventually the coolant in the oil would score and ruin the mains and rod bearings.

We have a few more people in here with more experience that will jump in soon.

[thamotivatedcouple]

the oil is good. No mixture with coolant present whatsoever. Same with the tranny fluid. I just plan to drive it around the block, as it hasn't driven yet in over 6 mos. I disconnected the tranny lines from the radiator and put the cooling system under pressure, but there was no signs of it leaking internally with the tranny fluid system. No leaking that was observed from the lines. The dipsticks from the tranny and oil look good, and I tool a sample of oil from the oil pan. Havent checked the tranny fluid yet, aside from the dipstick.

[4.3LXJ]

My 2 cents is that the snot is oil and water/coolant emulsified together. I am with Tony with the idea you might have a leak in the coolant coil in the radiator. And I hate to tell you this, but I think those radiator cooling tubes are probably plugged up. To check that unhook the hoses and shove a hose in one port, seal it off as best as you can, rag or something and let her rip. You should have a nice easy flow. If not ............. well

[thamotivatedcouple]

My 2 cents is that the snot is oil and water/coolant emulsified together. I am with Tony with the idea you might have a leak in the coolant coil in the radiator. And I hate to tell you this, but I think those radiator cooling tubes are probably plugged up. To check that unhook the hoses and shove a hose in one port, seal it off as best as you can, rag or something and let her rip. You should have a nice easy flow. If not ............. well

I did put it under pressure, and it was a smooth steady flow.

[Carves]

.................. She loves this jeep and wants to keep it until the zombies come (they cant come soon enough, lol).


Sadly ... that yellow snot - is ...... zombie ooze .. ;);)

Time for her to change vehicles .. :D:D


Sounds like you have some work in front of you.

My thoughts are a oil and coolant mix too .... but if you are certain there is no mixing happening ... It could all well be - just the cooling system and some form of stop leak or something ??

- Probably going to need some sort of "trusted" chemical cleaner to clean out the engine galleries,
- At a guess, I would say that gunk - occupies most of the radiator ... and there is very little, effective cooling, happening ... probably want to consider a newie on your shopping list ;),
- Really should have a thermostat in there ... temp range is your choice - but the flow restriction any t'stat provides - may be a requirement,
- Had the waterpump off yet ?? ... it pays to check that the impellor is all there - and moving coolant as it should - rather than being rotted off.
- Might even be worthwhile thinking about replacing all the welch plugs/freeze plugs while you're at it ?? ... Side benefit of that nasty little job - is that you get a look at the condition of the water passages.

[thamotivatedcouple]

Sadly ... that yellow snot - is ...... zombie ooze .. ;);)

Time for her to change vehicles .. :D:D


Sounds like you have some work in front of you.

My thoughts are a oil and coolant mix too .... but if you are certain there is no mixing happening ... It could all well be - just the cooling system and some form of stop leak or something ??

- Probably going to need some sort of "trusted" chemical cleaner to clean out the engine galleries,
- At a guess, I would say that gunk - occupies most of the radiator ... and there is very little, effective cooling, happening ... probably want to consider a newie on your shopping list ;),
- Really should have a thermostat in there ... temp range is your choice - but the flow restriction any t'stat provides - may be a requirement,
- Had the waterpump off yet ?? ... it pays to check that the impellor is all there - and moving coolant as it should - rather than being rotted off.
- Might even be worthwhile thinking about replacing all the welch plugs/freeze plugs while you're at it ?? ... Side benefit of that nasty little job - is that you get a look at the condition of the water passages.

Buwahahaha... I will tell her that... lol, copy that. I will take a look at a new radiator and I already have a new thermostat. Just waiting to figure out the situation before installing. I will ask her about the water pump as I do recall she had it replaced maybe a year ago? Ill find out for sure and let you guys know. Any suggestions with the radiator cleaner? I used prestone's radiator cleaner already once for about 20 minutes yesterday.

[Mudderoy]

Buwahahaha... I will tell her that... lol, copy that. I will take a look at a new radiator and I already have a new thermostat. Just waiting to figure out the situation before installing. I will ask her about the water pump as I do recall she had it replaced maybe a year ago? Ill find out for sure and let you guys know. Any suggestions with the radiator cleaner? I used prestone's radiator cleaner already once for about 20 minutes yesterday.

If you replace the radiator flush that heater core out really well so you don't recontamination the radiator.

[tommy guns]

I know people that worked at scrap yards,when the cash for clunker thing was going. They poured glue into motors and transmissions,hopefully that isn't the case here.

[bigjim350]

Have seen that "snot" many times. Its when oil is mixing with the water. Seems to me like its a cracked head, or a very blown head gasket. Here is a pic of the intake on a ford truck I had. The head was cracked on it very bad and let tons of water into the motor, so much that it ended up in the intake.
http://i20.photobucket.com/albums/b249/bigjim350/IMG_20120402_144125.jpg

[abebehrmann]

Found this pic of transmission fluid mixed with antifreeze in a Mercedes transmission. Looks a lot like your snot. Not sure what the pressures are like in the radiator between the coolant and the trans fluid but if the trans fluid is at a higher pressure, then that might explain why the trans fluid looks ok but the cooling system looks like crap.

[4.3LXJ]

Buwahahaha... I will tell her that... lol, copy that. I will take a look at a new radiator and I already have a new thermostat. Just waiting to figure out the situation before installing. I will ask her about the water pump as I do recall she had it replaced maybe a year ago? Ill find out for sure and let you guys know. Any suggestions with the radiator cleaner? I used prestone's radiator cleaner already once for about 20 minutes yesterday.

Since the water pump was replaced, verify flow. There are two water pumps that will fit the 4.0. But they have opposite rotations. If you have the tstat out, revving the engine should give you enough water out the upper hose to put out a small house fire

[reddragon72]

It's a leak in your cooling line from the tranny! been there done that with four vehicles!!! You will never see it in the tranny fluid because the cooling lines from the tranny are at 100+ PSI. It is usually a very small pin hole that spits the tranny fluid into the radiator.

Trust me you need a new radiator or if you have a seperate cooler then bypass the radiator part. Just remember to close up the two holes in the radiator or else it will spew out!

Sorry for not catching this earlier but been busy with buying a house and work!

FYI for good measure do a tranny flush as well. Coolant will kill seals in the tranny!

[thamotivatedcouple]

Ok, now I will triple check the radiator. I just replaced the head gasket, it was very warped and had a few rotted away spots. After replacing the head gasket, it ran better, sounded better, but still overheats. It is slower to overheat this time though. I put some radiator cleaner in it again. What's the next step? The water pump looked good and spun good, I will check the flow to it sometime tomorrow. I have read all the posts, and want to thank everyone for the tips. The temp seems to stabilize at around 245-255 deg and only gets to 260 when it idles for awhile. But it still took like 15-20 mins for it to get that hot though. I miss my Subaru... Lol.

[4.3LXJ]

Both fans working? Shrouds intact? Fan clutch working properly?

[XJ Wheeler]

Both fans working? Shrouds intact? Fan clutch working properly?

This is a ZJ so it would only have one fan and shroud. ;)

Sent via messenger pigeon - i talk, he types.

[4.3LXJ]

OK, so same question with only one fan involved

[XJ Wheeler]

Man, you're quick!