Back of engine coolant leak.
 

What’s up everyone. I’m new around here and I’m hoping some of you can help me with a problem I’m having. I did a search but didn't find anything.

I have a 2000 XJ that I’ve owned since 2002. This thing has given me zero problems in the 100,000 miles I’ve put on her (total mileage is 148000) but lately has developed a coolant leak that seems to come from the back of the motor. When I park it and it sits I can hear and see the coolant dripping onto the exhaust, I can also smell coolant when I drive it.

The jeep runs fine, I’ve only had to add coolant twice a month or so, so the leaks not terrible. My oil was normal when I changed it last week and it doesn’t show any signs of vapor in the exhaust. Any ideas?

You could have a loose or cracked coolant hose. Not terribly familiar with the coolant systems on the newer models but I would inspect all the hoses to start with. May have to drain it and take them off or get a dental mirror and look around under the back ones. Also check the thermostat housing and see if there is any leakage around it.

Check your heater control valve.

Big chunk of black plastic with 3-4 heater hoses going to it.

Should be right in front of your transmission dipstick.

These are known for cracking.
The constant heating/cooling/heating/cooling effects the plastic, making it quite brittle.
Brittle to the point of looking at it funny :wacko: can cause it to crack.


If it IS the culprit, they are easily replaced. Not often a clean job, but an easy one.

There is a freeze plug right on the back of the motor above the transmission and below the head. You'd have to use a mirror to see it. They can leak also. That would be about the right location to drip onto your exhaust...
You need to source the leak before you do anything, we are only guessing here, you have the source in front of you...
Mike

Great thanks for the tips guys. I'm going out there with a mirror right now and I'll see if any of the ideas mentioned help me out.

Ok so I checked out that freeze plug and it shows no signs of leaking. Also checked out all the connections to the heater core area and didn't see anything wrong there.

Now here's where it gets weird. My thermostat housing IS leaking. Is there a way that coolant could get to the back of the motor from there? Seems like it would be unlikely, then again if that's the only problem its an easy fix.

whatever you do dont buy the cheap gasket thats like a dollar at autozone, its felpro, they arent good they leak quick and the guy even told me they have been having lots of problems with them. buy the better one so you dont have to do it all over

The fan is blowing the coolant back towards the rear of the engine. See if you can follow the path.

FelPro is a very good brand of gasket.

I don't know who makes AutoZone gaskets. They may not be FelPros.

OK so while I have it off is there a different thermostat I could put in to keep it cooler? It seems to always just barely be a little over 210.

Don't do that. Give it a good flush, including the radiator, the heater hoses that feed the heater and the block. You can even buy some flush to really get the crap out. You can take the radiator to a radiator shop and have them flush it for cheap. If your system is operating efficiently and you do a really good flush including taking the radiator to someone to flush it properly, I guarantee you will be running like the days of old! Unless you need a water pump... Maybe you ought to change that too. You have plenty of miles! If it was me I would...
Mike

Hmmm...your probably right. Draining the cooling system would make both jobs easier.

I'll bet money that it is indeed a heater control valve i have replaced one on my current XJ and on my old XJ as well.....As stated it is very easy fix but it does get a little messy when you take the hoses off....Also when you do tackle this job make sure that the motor has cooled for a few hours that way you dont get burnt with hot coolant........:thumbsup:

yeah i know felpro is what the brand it was but their gasket for the thermostat is flawed:hang: i bought it myself against the guys advice and it leaked:stupid:

Ya know, its not polite to say "don't use this" WITHOUT giving a "I used THIS" following it.

:thumbsup:

What brand gasket worked for you?
Where did you get it?

Don't leave us hanging man
:hang: