Cmcilm94

Hey everyone!

This is my first post on this site and I am currently going through the pre-troubleshooting steps on my first Jeep. I just bought my Cherokee about a week ago and I've been fixing it up but now I've seem to run into an overheating issue. I have really began any of the troubleshooting steps but I would appreciate any advice after I provide the information I already know. Okay, so last night I was on the highway and my check gauge light came on and my temp gauge was at 250 but as I cruised down the road for another 30 seconds it literally went from 250 to 210 in the matter of seconds, it did that once more last night and again today but shortly there after it was happening again. But I was just cruising and keeping my eye on it and then I stepped on it and low and behold it has shot up to 260 and wouldn't come down, luckily I was pulling in the driveway. I got out and noticed a lot of smoke coming from the driver side, like back by the firewall where you can see the trans. I got under and noticed coolant dripping off of the trains where it meets the engine, but it looks like it ran down there from somewhere up high. Also, I don't think the heat is working very well. So I'm trying to come up with a course of action, obviously I'm thinking thermostat but why would it be leaking. Any ideas? Thanks everyone, I appreciate any input.

toasterknight

I would start with a flush. The leaking could be the freeze plug on the rear of the engine. It may also be a fan clutch. Radiator plugged. Water pump dead. Head gasket. If the heat isn't working well I would assume it needs a thorough flush.

Wayne,Az

Check the plastic heater control valve,passenger side toward rear of engine..Wifes 94 started leaking after about 180k and 18years of use.Easy and cheap fix.

toasterknight

99 doesn't have that valve.

Cmcilm94

Coolant in the radiator, looks and smells burnt.

toasterknight

Looks like a lot of deposits as well. I would back flush the entire system until it ran clear.

Cmcilm94

Yeah, I agree with that. I got down with a mirror and looked at that rear freeze plug and although I can't see any physical pooling of coolant it sure is very wet back there and it would make sense for it to leak down where I saw it dripping.

toasterknight

I have never done one but there are threads all over the place about changing them and someone may come along with advice on how to do them.

Cmcilm94

I'll take a look around so thanks. But that wouldn't explain the overheating.

toasterknight

It doesn't but its still a problem.

Cmcilm94

Thought I'd put and update of what happened. Okay, so I am very happy to say that I solved the issue. I decided to start with a flush but I didn't want to flush it with an old thermostat and water pump so I decided to replace the both of those along with a very VERY thorough flush of the whole system (new pump and 195' t-stat was only $30 at oreillys so I thought why the hell not) I had also discovered that the heater core inlet tube that threads into the water pump was rotted out and was leaking and let me just tell you how baffled I was that my local oreillys had one in stock for only $9. Definitely thought it would be a dealership part. But after hours of flushing until water was coming out clear I filled her up with fresh coolant and now it won't even go above 210 degrees. It stays right between 200 and 210! Beautiful if you ask me. Also, piping hot hear being blown now too. I came to find that the pump that was in it was in fact factory, 181,000 miles old. Also I did a pretty good inspection and found none of the freeze plugs to be leaky and I even kinda think the plug on the head is newer. Anyway, I'm pretty happy with how this turned out. It really kinda taught me the importance of good coolant. So now I can check that issue off the list!

toasterknight

Glad you got it working properly.

Fred/N0AZZ

On that bad boy flush, then run cleaner, then flush again till clean and clear make sure the heater core is opened when doing this.