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:

The coolant is probably running down the hose and block from the thermostat housing. Mine did that which is why I said to check it. Also a lower temp thermostat might be a good idea. Flushing as mentioned above is good but I had my cooling system flushed really good proffesionally and it still runs just over 210... Get the new thermostat and a junk yard Audi twin fan..

Any recommendations on a thermostat? My jeeps has run at a hair above 210 for years now so I'm not sure If flushing will fix it although I will probably go ahead and flush the system anyway.

Got a write up for installing the Audi fan you mentioned or is it pretty much a no-brainer?

I didn't see any leakage around mine, is there something specific I should be looking for? A picture would be golden...

the OEM thermostat is a 195, you can go down to a 160 or try a 180. I'm gonna put the 160 in mine until winter and see how it does. For the audi fan you might be able to find a write up somewhere on here but I think its pretty simple.

Awsome! Thanks for the info :thumbsup: ...now off to Napa...

So you bought the Jeep with 48,000 miles on it, you said it has always run a hair over 210 on the 100,000 miles you have driven it. It is still running a hair over 210, it has a small coolant leak and you want to replace it with a lower thermostat to fix what? To lower the 210 it has been running at for 100,00 miles? Or install an Audi fan? To fix what?
Why don't you fix the leak and call it good? At this point of the game installing a lower thermostat is riduculous. Install the 195 and drive it for another 100k. Installing an Audi fan is totally unnecessary... Have you checked the coolant temperature to make sure your gage is correct? Shoot the inlet and outlet hoses with an IR gage. Test the thermostat... Don't go down the path you are taking!
Think about the advice you have been given before acting! Does it make sense? It does not to me! Find the Leak!!!! and fix it!!!
Mike

Well the thinking goes something like this: Leak has been found, at least A leak has been found. If I'm going replace the gasket anyway then I may as well put in a new thermostat since the one that's on there is stock as far as I know. I'd rather replace it now while I'm in there rather than have it crap out on a trail somewhere.

I should have clarified the over 210 thing. Its done that for several years now, when I first bought it it never broke 210.

I don't have one of thermometors your talking about but a new thermostat is dirt cheap. I see no harm in going with a 180 instead of the stock 195 especially since the places I go tend to be pretty hot. The coolant flush is something that also should be done considering its been about 5 years since I did it last.

The Audi thing is more of a curiosity than anything else. Lets face it modding stuff is fun!

Running a 180 stat usually puts you right on the edge of running too cool. If you don't get up to the proper operating temp the computer will stay in closed loop mode. That's the mode it's in when you first start it when cold. The computer makes it run rich when first started. If it never hits the propoer operating temp it will stay in closed loop mode all the time. It won't go into open loop where the O2 sensors are feeding back into the computer. You will burn more fuel, you will dump more raw fuel into your exhaust system and the cat thus lowering the life of it. Some people get lucky with the 180 stats and they run ok, others run into what I described. Check your mileage before and after so you can see how much money it will cost you in the long run for the 180 stat...
Then maybe a flush and returning your system to it's original state as designed by Engineers who may know a little more than your average goat, won't look so bad...
Good Luck

I agree with both. Running just over 210 isn't that big of a deal. The reason I'm going with the 160 and new fan is because I live in Denver and one trip up I-70 into the mountains and just over 210 turns into red city. (plus mine dies when it gets over 210 but thats another thread) I'm sure it will still get hot but will be enough buffer to get to that downgrade without going into the red. (I'm also pulling a 18' sea ray). In agreement with Mike, replacing the old gummed up 195 with a fresh one and a coolant flush might put you right on the money... Your jeep, have fun! :thumbsup:

Well here’s an update on the situation.

I replaced the gasket and the stat, flushed the system and now she seems to be running at a steady 200. The weathers been mild and I haven’t really stressed the motor much so I think things will work out for me in that regard.

Now the problem, I’m still seeing a trace of coolant on top of the water pump. A leak still seems to be there somewhere albeit not nearly as bad. Now there just seems to be a few random drops of coolant on the ground, none on the exhaust and I’m not smelling coolant all the time anymore.

This leads me to three possibilities:

1. I screwed up and installed the gasket improperly (Least likely, simple job, took my time and made sure I did it right.)

2. Gasket is faulty. I called several places around my area and only one parts store had one in stock so I bought it. It was light blue and had an adhesive backing on one side, not sure of the brand. I see that some of you mentioned not getting the basic one so maybe that’s what I ended up with.

3. Both water pump and stat housing were leaking. Fixing one helped the problem and now I need to do the pump as well.

Sucks cause I’m at my girlfriends for the weekend, don’t have my tools and her landlord freaks out if someone looks like their working on a vehicle in the complex. It looks like it’s going to have to wait until early next week till I can investigate further.

Is the coolant coming out of the weep hole on the water pump? That means the pump is toast if it is.
Congratulations on the rest of the job! You have fixed your Cherokee properly! I'm glad you didn't go with the lower stat. There is no need for that on a properly running cooling system.
Mike

My own leak
 

Does anyone know what the nut or bolthead(cant remember what it is exactly) is above the engine block drain plug? It has an oversized washer underneath it. My coolant is leaking from there and was wondering if anyone could help me figure out why and how to fix. My jeep has been overheating and I figured out thats where the leak is coming from. Thanks.

Are you looking on the Drivers side? There is a freeze plug above the drain for the block on mine???

yes its the drivers side that i;m talking about. it looks like there are two of them. it's leaking out of the front one.

I'm looking at my 1998 block and I don't see anything other than the drain plug that would leak. Can you take a picture? Maybe someone else can help us. If it's overheating and the coolant level is ok, you have more issues than that. Is it leaking enough coolant where it is getting low then overheating?