Hey guys, I'm hoping you can help me with this one,
My '94 Grand Cherokee with the 5.2 v8 has been having problems. All of the anti-freeze will spill out onto the ground once I stop after I've been driving in hot weather. It come out of either the cap or the over-flow tank - one time its one, and the next it could be the other. I just haven't pinned down why. I thought that maybe the relief valve in the cap was too low, so I tried another one, but still over flowed. I also usually don't notice a temperature increase while driving, just that when I stop it sometimes spews. Lately, though, I've noticed that it moves from the tick below 210 (Are they 10 degree increments? Hard to tell since the scale isn't linear) up to 210. When pulling a friend's boat I noticed this, but it didn't spew at the gas station (40 miles into the drive) so I figured we were ok, but about 15 miles further down the road at the bait store the radiator emptied. (Through the cap.) After the drive back I had my buddy hose down the radiator before I shut the car off to increase cooling. No overflow, but I don't want to be required to do that each time I drive.

Thoughts? Thank you!

Your thermastat, I would say is dorked, your engine allways gets hotter after you shut it off, since operation of the engine just "stops" when you turn off the key all the heat that would be taken away during running is stopped and the heat builds up.

Under normal operation the system will still get hot but it does not overflow, I think you stat is closeing to soon and the pressure of the heat build up is being pushed back into the rad from the lower hose and since it's hot the pressure is acting on the Rad cap and into the puke tank.

Thats the best idea I have, if anybody has a better one I would love to hear it.

I just did mine on my 98 JGC 360 it't the same as yours, if you going to do it yourself buy the HIGH TAC gasket maker as well as a gasket and a 180 stat, not the 190, I think Jeep messed up doing this on the V8s.

The stat houseing is kinda hard to get out between the AC and Genarator, but just wiggle it, whats going to be messed up is getting the old gasket off, what a time I had with that, I had to use my dremel and a brass wire wheel. You going to puke coolent all over unless you drain some from your rad, and your still going to have it all over the place, so remember if any thing drinks that stuff they are going to die!!! So dont kill anything and hose it away if you spill it.

Put the gasket stuff on the paper then let it tac up as directed on the tube, put the gasket with the goo on it on the intake, don't put it on both sides because you will get it all over everything , then put the gasket maker on the cleaned steel houseing, try to get it on once, I mean set it down once, if you tag it the gasket may move, and you really cant see that good down in that area.

Tighten them down to factory numbers useing some anit lock on the bolts, Alum and steel suck together

(1987 K5 4x4 350 stat bolt= 4 broken taps 3 broken drill bits, my fathers and my blood and talks to god a chain tow job to a machanic and his 2 broken drill bits and 2 taps and a non stock oversized bolt and $40)

Sounds like theres too much coolant in the overflow tank, shoul dbe at the ADD mark on the tank when the engine is completely cold.

I have the same jeep (94 5.2L). When I replace the thermostat (I used a 160 Degree T-Stat) I remove the whole accessory drive bracket, it is a lil more work but will make the job a lil easier. the increments are about 27 degree (100, 127.5, 155, 182.5, 210). after putting in a 160 degree T-Stat I am now running between 150-160 degree (depending on if I am using AC or not, with ambient tempautre 85-90 degree)...

When you look at the area, it seems that you can get it done with only a little problem, thats without removing the accessory drive bracket, however you can do the job without removing it. If you have to scrap off gasket you can use a drem, or a drill with a brass wire wheel, the intake is Alum.

I would say that it would have been less a problem takeing off the accessory drive bracket, because I kept getting my deep well stuck as well as fishing the houseing around I will next time take off the accessory drive bracket, however you dont have to...

Your thermostat is probably okay otherwise you would overheat going down the highway. I would replace your radiator cap as it isn't holding the pressure in your radiator thus allowing the coolant to go to your overflow tank. When you turn your engine off the water is not moving through the radiator any longer thus the temperature will go up along with the pressure in the system. A good radiator cap will control this.
If you had any other problems such as a water pump or thermostat or clogged radiator you would notice the over heating problems while you were driving and the engine was underload. I had the same problem. I would turn the engine off and the overflow tank would start to bubble as the pressure was released into the tank. New cap = no more bubbles.

He replaced the cap.

Other then a cloged Rad it has to be the stat, I'm saying it's closeing to soon, I may be wrong howevr it's worth trying.

Thanks for all of the possibilities. As for an update, the car began loosing fluid even when not stopped, and I was able to find a leak in the radiator. Maybe the problem all along is that I was loosing enough fluid that the car would just over heat. I'm not completely convinced, but either way, the radiator needs to be changed. I was planning on doing it this weekend, but made a few calls and a place down the street would replace it for only $60 more than I could get the parts for. For that kind of money I'd rather take the day to go fishing. Hopefully this helps the problem. I'll be driving down to South Padre Island for the Fourth, so it will get tested. A road trip in the South Texas sun is a pretty good test for a cooling system. :) (I'll be bringing extra antifreeze just in case - the propylene glycol stuff instead of ethylene glycol so I don't kill the wildlife if it does go.)

Thanks for your help, if this doesn't work I'll definately be changing the thermostat.

Good luck, great idea about the Anti-dead-Anti-freeze.
If you find out what the problem is, let us no, so the info can be passed on.

Happy 4th

Well, the new radiator wasn't quite the fix that I'd hoped for. THe temperature gauge still had way more movement than I've come to expect. However, the coolant stayed in. Like I mentioned before, my next step was to try a new thermostat. Which I did. But I screwed it up and cross threaded the bolt on the left and now it wont hold pressure. >:( I'm upset with myself on that one. I shouldn't have tried to rush the job an hour before a road trip. Has anyone out there helicoiled that part of the engine? Although if I couldn't manage to just screw in a bolt in such a tight spot, I'm not sure if I should attempt to re-thread it with the helicoil. I suppose I'll need to defer to a professional. Any thoughts on the cost of this job?

And I still don't think I've quite fixed the temperature problem.

Thanks for your help.

I had this same exact thing happen to me.
That is why i remove the whole Accessory Drive Bracket.

You cross-threaded the left bolt (looking at it from the front), toward the Altenator, right?

I did the same thing on my 87K5 Blazer 5.7 it was crazy, I broke the tap off in the hole trying to coil it, well then the next 4 drill bits got broke trying to re drill the hole, as soon as it hit the hard tap piece it snaped the drill bit, then I had a tap piece and a drill bit piece in the dam hole, so me and my dad towed it to a shop for them to fix it, let me tell you what happened next.

The guy drilled everything out with a bigger bit and then broke off his F'n tap!!!! I didnt feel as bad when the pro did it, he ended up snaping 2 standard bits so we had to use his metric set and metric bolt that was 2 sizes to big, but it held a seal.

All in all, when I did my GTO stat I used studs, and I plan on useing them when I change to a 185 stat in my jeep at the same time replace my Rad with a steel unit along with T-bot hose clamps with new hoses.

After I replaced my stat on my jeep the factory spring clamp didnt hold good enough and started driping a little, so I replaced it with a worm clamp, but since i'm redoing the cooling system I'm going with NHRA spec cT bolt clamps.

I feel bad you crossed your bolt man, Alum and Steel were never ment for each other like that, if you can use Studs next time, Lows sells them in the bolt isle.

Good luck

I had this same exact thing happen to me.
That is why i remove the whole Accessory Drive Bracket.

You cross-threaded the left bolt (looking at it from the front), toward the Altenator, right?

Yup. That's the one.

And after RamAirGTO72's responce, I think I'm going to take it in to a shop and have them mess with it.

Thanks for the help.

ColdPass

I did the same thing to the same bolt. I did manage to remove everything (Acc. Drive Bracket, T-Stat housing) and then re-tap the hole.