Shane Posted October 11, 2008 Share Posted October 11, 2008 I got home from work one day and as I pulled into the driveway I noticed that my MJ was smoking from under the hood. When I stopped and raised the hood I heard a bubbling sound and the coolant running out from the resivour. My temp ;ight never came on, but my battery gauge did. I put on a thermostat, changed the radiator hoses, put on a new water pump, and had the altenator rebuilt which it was almoast shot. After all that I still have thecoolant bubbling over. There is no water in the oil or no oil in the water. Soa what could this be? It is an 89 automatic 4x4. Any advice is greatfully appreciated. Thanks, Shane Link to comment Share on other sites More sharing options...
Eagle Posted October 11, 2008 Share Posted October 11, 2008 Do you still have the original cooling system, with the plastic reservoir on the passenger side of the firewall? If so, one possibility (probability, more likely) is that the cap isn't able to hold pressure any more. In the 87 - 90 4.0L cooling system, that bottle is not an overflow recovery bottle. It is a part of the pressurized system, and that cap is a pressure cap. When they get old, being plastic, they lose the ability to seal. The other point is ... how full do you fill that reservoir? There is NO overflow for the "closed" system -- which is why it is nick-named the "closed" system. There has to be air in the system to allow for expansion. If you look into the opening in that reservoir bottle, you'll see a post sticking up. That's how full you should fill it when the system is cold. It fills to the halfway point of the bottle, with the additional volume to allow for when the coolant gets hot and expands. If you've been filling it up to the top -- you've been over-filling it, and stressing the pressure cap in a way it wasn't designed to be stressed. Quadratec used to sell a complete replacement (plastic) bottle for $19, with cap. It's probably a few $$$ more now, but ti's still the cheapest way out. There are other solutions available using high quality aluminum parts, but they're a LOT more money. If you're interested, I'm sure a search will turn up the discussions. Link to comment Share on other sites More sharing options...
comanche87 Posted October 11, 2008 Share Posted October 11, 2008 i had a problem similar to that. it was the bottle with the cap. my bottle cracked cuz it was old and it was bubbling up like crazy and pissining everywhere. get a bottle with cap and that should solve your problem. Link to comment Share on other sites More sharing options...
mjdoa Posted October 11, 2008 Share Posted October 11, 2008 Shane,first confirm that it's not actually overheating. The idiot light is not the most accurate indication. Just as an fyi for everyone,I found that mine runs a bit cooler if I overfill the system by a quart or two. Don't know why. Link to comment Share on other sites More sharing options...
BLHTAZ Posted October 11, 2008 Share Posted October 11, 2008 You MUST make sure that you bleed ALL of the air out of the system when you have had it open & refilled. The closed system is very sensitive to air in it as I found out when I first got my truck ;) . My method of bleeding works without running then engine and requires it to be cool... 1.) Park the truck with the front end pointing down hill or jack the back end up as high as you can if you don't have a sloped area to work with. Allow it to set for a few minutes to get the air to accumulate at the high point in the rear of the head. 2.) Locate the temperature sender at the right rear of the head just under the MAP sensor. (I found it easier to remove the MAP sensor to get to it with a socket & extension). (not a Renix engine pictured, but it shows the location) 3.) Be sure that your coolant is propoerly filled and remove the sender, but don't go far with it as the air will bubble out and then the coolant will start to flow so you will need to be ready to put it back in quickly. That should have the air out. Check your coolant level again after this process and then take it for a ride and see how it works. It should not heat up again (unless you have other issues), but if it does, repeat this process one more time AFTER IT COOLS DOWN. Mine worked with one try though :cheers: Link to comment Share on other sites More sharing options...
mvusse Posted October 11, 2008 Share Posted October 11, 2008 And if you are in fact overheating, have the radiator flow tested. As for filling the closed system, I take the cap off the pressure bottle and the upper radiator hose off the thermostat housing. I then fill through the upper radiator hose until it is up to the correct level in the pressure bottle. Put the hose back on and replace the cap. There will be some air in the system, but never had a problem yet by doing it that way. Link to comment Share on other sites More sharing options...
Shane Posted October 13, 2008 Author Share Posted October 13, 2008 Now I have replaced the cp to the jug. It sill blows the coolane out but not as bad. What else could it be. A friend of mine told me that it could have a cracked head, but I do not see that bring that there is no water in the oil or vice versa. Just to check things off the list: New thermonstat, new radiator hoses, rebuilt alternator, new battery,( I know that has nothing to do with prob, but it neede it too) and new cap for the coolant jug. As always any advice is appreciated . Thanks Shane Link to comment Share on other sites More sharing options...
BLHTAZ Posted October 13, 2008 Share Posted October 13, 2008 You didn't mention if you did the air bleeding thing or not. What you are describing sounds like air in the system which is why I posted my previous instructions above for you ;) . Yours is doing exactly what mine did until someone told me about this process and I did it. If you have done that and it is truly overheating then there are a few things it could be including head gasket, radiator, clogged catalytic converter, plugged hose going to the bottle etc, etc... Link to comment Share on other sites More sharing options...
Eagle Posted October 13, 2008 Share Posted October 13, 2008 Now I have replaced the cp to the jug. It sill blows the coolane out but not as bad. What else could it be. A friend of mine told me that it could have a cracked head, but I do not see that bring that there is no water in the oil or vice versa. Just to check things off the list: New thermonstat, new radiator hoses, rebuilt alternator, new battery,( I know that has nothing to do with prob, but it neede it too) and new cap for the coolant jug. As always any advice is appreciated . Thanks Shane Assuming you still have the OEM plastic surge tank, replacing just the cap is not going to resolve the problem. The tank and cap should always be replaced together. Link to comment Share on other sites More sharing options...
chicofuentes0224 Posted October 13, 2008 Share Posted October 13, 2008 Before you go and do anything else, go to Autozone and buy yourself a digi thermometer. They're around $20. Shoot differnt areas around the thermostat housing and get us a good reading. Then we'll go from there. If you search on the forum you'll find a lot of differnt things. Look up "Chico's 1988" in the MJ projects section to see what I replaced my plastic tank with. But first find out what temp your engine is actually running at. And bleed the system like BLHTAZ told you. Link to comment Share on other sites More sharing options...
SuperWade2 Posted November 15, 2008 Share Posted November 15, 2008 You MUST make sure that you bleed ALL of the air out of the system when you have had it open & refilled. The closed system is very sensitive to air in it as I found out when I first got my truck ;) . My method of bleeding works without running then engine and requires it to be cool... 1.) Park the truck with the front end pointing down hill or jack the back end up as high as you can if you don't have a sloped area to work with. Allow it to set for a few minutes to get the air to accumulate at the high point in the rear of the head. 2.) Locate the temperature sender at the right rear of the head just under the MAP sensor. (I found it easier to remove the MAP sensor to get to it with a socket & extension). (not a Renix engine pictured, but it shows the location) 3.) Be sure that your coolant is propoerly filled and remove the sender, but don't go far with it as the air will bubble out and then the coolant will start to flow so you will need to be ready to put it back in quickly. That should have the air out. Check your coolant level again after this process and then take it for a ride and see how it works. It should not heat up again (unless you have other issues), but if it does, repeat this process one more time AFTER IT COOLS DOWN. Mine worked with one try though :cheers: Holy old threads batman... Hey Brent, tried this today... MJ parked in driveway, nose down (fairly steep), I pulled the Temp sensor all the way out and no coolant came out... does that mean there's not enough in my system? When I'm "level" and cool, the fluid in the pressure bottle is right about (maybe a smidge under) 1/2 way... Maybe I didn't do the right thing, this was the sensor that I replaced when I went from dummy gauges to temp gauges console... I remember getting rad fluid out when I installed the sensor. Link to comment Share on other sites More sharing options...
BLHTAZ Posted November 15, 2008 Share Posted November 15, 2008 Wade...that's a strange one... :hmm: I have used this method on three different vehicles now (my MJ & two XJ's) and I have never had one that didn't flow out freely :nuts: . It would seem to me that the coolant would have to be VERY low in order for that to happen, but if your bottle is staying at the proper level...that doesn't sound possible :???: . Link to comment Share on other sites More sharing options...
jtdesigns Posted November 15, 2008 Share Posted November 15, 2008 SWII did you uncap your bottle when you pulled the sensor?? Link to comment Share on other sites More sharing options...
BLHTAZ Posted November 15, 2008 Share Posted November 15, 2008 SWII did you uncap your bottle when you pulled the sensor?? :idea: Good question... Link to comment Share on other sites More sharing options...
SuperWade2 Posted November 15, 2008 Share Posted November 15, 2008 SWII did you uncap your bottle when you pulled the sensor?? Uh...no... Didn't know I was supposed too... Link to comment Share on other sites More sharing options...
jtdesigns Posted November 15, 2008 Share Posted November 15, 2008 Well its like holding your finger on a straw... it won't move without a little displacement of air. At least thats what I'm thinking. And your truck needs to be a little warm not hot. Link to comment Share on other sites More sharing options...
BLHTAZ Posted November 15, 2008 Share Posted November 15, 2008 SWII did you uncap your bottle when you pulled the sensor?? Uh...no... Didn't know I was supposed too... Guess I didn't think about that being a step in the process as I just did it automatically :oops: ...sorry. I'll go add that to the DIY post. Link to comment Share on other sites More sharing options...
SuperWade2 Posted November 15, 2008 Share Posted November 15, 2008 SWII did you uncap your bottle when you pulled the sensor?? Uh...no... Didn't know I was supposed too... Guess I didn't think about that being a step in the process as I just did it automatically :oops: ...sorry. I'll go add that to the DIY post. :doh: :doh: :doh: :doh: Link to comment Share on other sites More sharing options...
BLHTAZ Posted November 15, 2008 Share Posted November 15, 2008 :doh: :doh: :doh: :doh: Your being nice... :yes: It should have been a :thwak: or a ...or both... Link to comment Share on other sites More sharing options...
chicofuentes0224 Posted November 15, 2008 Share Posted November 15, 2008 Wade, did it work? Link to comment Share on other sites More sharing options...
HOrnbrod Posted November 15, 2008 Share Posted November 15, 2008 :doh: :doh: :doh: :doh: Your being nice... :yes: It should have been a :thwak: or a ...or both... I don't see how this method can get all the air out of the system if it's not warmed up. There will still be air trapped in the stat housing since the thermostat hasn't opened, unless you use the stat with the hole in it, right? Link to comment Share on other sites More sharing options...
BLHTAZ Posted November 15, 2008 Share Posted November 15, 2008 That would be correct Don. This method ASSumes that you have the proper t-stat in the engine and not a cheap aftermarket one. The proper ones from the dealership have the vent hole in the top. Link to comment Share on other sites More sharing options...
Pete M Posted November 15, 2008 Share Posted November 15, 2008 Hey Brent, tried this today... MJ parked in driveway, nose down (fairly steep), I pulled the Temp sensor all the way out and no coolant came out... does that mean there's not enough in my system? When I'm "level" and cool, the fluid in the pressure bottle is right about (maybe a smidge under) 1/2 way... Maybe I didn't do the right thing, this was the sensor that I replaced when I went from dummy gauges to temp gauges console... I remember getting rad fluid out when I installed the sensor. Did you have the engine running? Link to comment Share on other sites More sharing options...
SuperWade2 Posted November 15, 2008 Share Posted November 15, 2008 Hey Brent, tried this today... MJ parked in driveway, nose down (fairly steep), I pulled the Temp sensor all the way out and no coolant came out... does that mean there's not enough in my system? When I'm "level" and cool, the fluid in the pressure bottle is right about (maybe a smidge under) 1/2 way... Maybe I didn't do the right thing, this was the sensor that I replaced when I went from dummy gauges to temp gauges console... I remember getting rad fluid out when I installed the sensor. Did you have the engine running? Nope... another step I didn't see... I probably won't mess with again till later today or tomorow...so what is the "right" way to do it? Link to comment Share on other sites More sharing options...
Pete M Posted November 15, 2008 Share Posted November 15, 2008 The first time I ever heard about the procedure it was with the engine cold but running, and the sensor wasn't supposed to fully come out, just enough to bleed air out. I've not had the pleasure of doing it myself so I can't say. Link to comment Share on other sites More sharing options...
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