External head gasket leak? I mean, it's unlikely, but it's a possibility.

- More likely to leak when hot
- Leak wouldn't necessarily be located next to any hoses/fittings

 

That is possible.

I just wonder why it wouldn't show under a pressure test.

And they said they couldn't they find any dry coolant residue to possibly help find the source.

Head scratcher for sure.

Thanks for the reply.

Anybody else?

 

Pull the spark plugs and see if one is real clean. That would happen if the
head gasket was leaking into the cylinder and blowing steam out the tail
pipe. All the soot would be gone from the plug.

 

This was happening to me as well. I removed the thermostat housing, replaced all the gaskets and both thermostats. I noticed that one of my thermostat gaskets had a small tear in it. Since I changed those gaskets, I havent had an issue.

 

head gasket split between water conduits and exhaust side of combustion chamber? a small one that only opens up when hot

you would lose fluid, but it would be burnt in the exhaust, so you wouldn't find it, unless it also leaked to the outside world.....

how many km on engine?
have you always had the jeep?
any smell of coolant? if so, when and where?

 

I can't find a leak, but I know it's leaking because when I bought it 2 weeks ago, the resoivour was full, and just yesterday I had to fill it again. I can definately smell coolant after driving,but there are no visible leaks.The car doesn't overheat. It has 103k on it, pretty well taken care of from what I can see. I usually notice the smell of coolant after I stop driving, as soon as I get out the car. I opened the hood, and I can smell it, but I dont' see a single leak, on or around anywhere, and the fluid levles seem to lower not during the driving, but the next day when I check again, there just a slight bit lower, I marked them with a permament marker. Can the freezing cold temperature cause more fluid usage? I'm kind of ignorant when it comes to cars, but I didn't have this problem with my 2011 Hyuandai Santa Fe before the wreck. I don't remember ever putting coolant in it actually. They usually topped it off at Valvoline every 6 months or so, but this car, I haven't even had it a month and I've already had to fill the coolant resovoir twice.

 

wpeck2: It's about due for plugs anyway so thanks for the suggestion. I will change them this weekend and check.

philbobagginz: I did replace both thermostats about a year ago so I assume I also replaced the gaskets. But that is a possibility that one has failed.

harold: I do have a lot of coolant on the belly pan every morning so it's definitely leaking outside. That's why I'm confused why a shop can't find it. When I leave my house in the morning, I leave a trail of coolant in the street...the coolant that's piled up on the belly pan.

So it's almost as if it leaks after sitting from a day of driving. The shop only drove it about 20 mins so it wasn't the exact same conditions as me driving for a day.

I don't know. Confusing.

-140k miles (225k km)
-Owned it for 8 years
-I thought I smelled coolant in the vents but it was only one time. Heat works excellent. No leaks in cab. Smell might have been pulled from the engine compartment.

Thanks for all of the suggestions!

Keep them coming!

 

Check out the line from the overflow to the radiator and the radiator cap. My XJ was loosing coolant and it drove me crazy trying to find the leak turned out to be a small crack in the overflow line, it would only leak after running up to temperature and would stop as soon as the pressure equalized.

 

festerw: I haven't noticed anything wet in the engine compartment besides the wet belly pan. And you would think a pressure test would reveal a leak like that.

But I will definitely mess with that hose after a hot drive. And I should probably replace the radiator cap. It is original.

Thank you for the suggestion!

Anybody else?

 

The overflow system isn't under pressure so it won't show up with a pressure test.

 

You are right. I did check it yesterday and didn't see anything. The hose is pretty hard so I should probably replace it.

 

Update: I forgot to mention I sometimes hear a bubbling in the coolant when I shut down the engine. It seems to be around the main thermostat near the air box tube. I can feel hear and feel the bubbling through the top radiator hose.

Any thoughts on this addition? Are these bubbles possibly air being sucked into the cooling system from the leak point?

 

Update: I have found the leak source but still need help figuring out the problem.

This is what I know...

When I get home after a hot drive, with the engine off, I can hear the coolant bubbling around the thermostat housing. I can also feel the the bubbling in the hoses.

At this point, the reservoir is full and it starts to overflow out of the reservoir tank. So, the pressure in the cooling system is overcoming than the radiator cap spring, filling up the reservoir, and then overflowing the reservoir.

Then about 5 mins after it sits it will suck the coolant out of the reservoir which is why I find it empty every morning.

I hope this makes sense.

Could this simply be a bad radiator cap?

As I mentioned in an earlier post, a pressure test couldn't get it to leak which, of course, doesn't test the radiator cap.

Any thoughts on this?

Thanks so much for the help!

 

A new cap is a cheap test, buy a Stant or Mopar. If that doesn't solve it you'll want to get a compression test done to find out of you've got a head gasket problem.

 

It shouldn't be bubbling at all. That means it's boiling and is overheated. Does the temp gauge not show overheat temps?

You may possibly have air trapped in your cooling system that can be let out by running the jeep up to operating temp with the radiator cap off and wait for the thermostat to open. You should see the coolant level in the radiator fall at that point, then fill it back to the top.
Where there is air in the cooling system, there should be coolant that and will cause a car to run hotter than it should due to lack of coolant.

 

Festerw: I will buy a cap this weekend.

Griff: The temp gauge reads the same as always. I will run it up to temp this weekend with the cap off and see what happens.

Thank you both for the suggestions.

 

Update: Is was the freakin radiator cap.

It's a bit embarrassing to say but I was looking for a bigger problem than it really was.

And even more embarrassing for the shop I took it to. You'd think they would have visually inspected that cap.

Oh well. It's fixed!

Thanks for the replies!

 

My Wife's Patriot is doing exactly what you describe, it'll have a small puddle after its been running.

I even searched exactly "Mystery Coolant Leak"

I'm going to get a new rad cap and see if it solves it!

Thanks for your post and for updating it on the solution you found.


-Charles

 

twoweelz, Glad you got it figured out. Great contribution!
I am all to familiar with your story too. Hindsight is always so........late. There are night sight / vision goggles, why not...for hind......!
Any hays...my "two" cents is...in my pressure test kit there is an adapter for pressure testing radiator caps!

 

I had a similar, albeit much slower leak for the past year but it eventually showed itself to be coming from the bottom of the thermostat housing. You can get a leak where the evidence evaporates off before it runs down the hot engine and hits the belly pan or ground. In my case i could finally see it on top of the transmission. It was the housing-to-head rubber seal. Yours does seem more heavy than mine as i only needed a little coolant every few months. Some shops have a dye leak test fluid they can put in to help find it though and that may be your best bet.

 

So I have a really weird coolant leak that nobody can find. Over a year ago, I replaced the water pump, thermostat, and possibly the 2 main radiator hoses. I first noticed a small amount of coolant on the belly pan a few weeks ago when I removed it for an oil change. I searched everywhere underneath and on top and couldn't find anything wet. So I kept driving it. It will now use around a reservoir worth of coolant for one day of driving so it's definitely not a small leak. When I get home, I can look from above and see there is coolant on the belly pan. So I took it to the mechanic that I always use. They had it for 2 days. They pressure tested it twice and couldn't get it to leak down. I told them to drive it for a while and then test it. They only got it to leak a very tiny bit and were unable to find the source. But like I said, it will use an entire reservoir in one day. So maybe it only leaks when it gets really hot after a day of driving or after it sits from a hot session. It's never overheated and it still runs the same so I don't believe it's a head gasket. Didn't notice any water in the oil. I believe there is a funky aluminum pipe with o-rings that runs from the water pump to the thermostat housing. I wonder if that's the culprit. Any thoughts? Thank you!

Hey was the leak on the driver side of the car underneath it?????

 

Just replaced thermostat housing and checked pipes nothing drove it after getting it changed seemed all fine drove it again 2 hours later got home noticed small drops out of bottom guard pan can’t see it leaking anywhere ?????

 

check the cap t-fitting /plastic the sides get brittle and could be swelling and drying up most so you never see but a tint bit down on the radiator floor

 

My jeep Patriot 2007 model is working fine but the water in the radiator is drying off without any pipe leaking.
What could be the cause, how can it be rectified, can it be fixed?
Please provide detailed guide on how the repairer could fix it, it's currently in the mechanic workshop.

 

If your coolant is disappearing out of your radiator and there is no leak, the only place it can go is out the tailpipe via a cracked head gasket. Hopefully it's just a leak that you haven't been able to find...

 

You can also get a small leak that would run down the engine, but only when hot and so it evaporates before it hits the ground. This will often leave a color stain behind of whatever color coolant you're using and you can catch a slight smell of coolant while poking your head around under the hood. Evaporated coolant has a sort of sweet celery smell, at least that's what it reminds me of.

 

I am having the exact same problem, does anyone have experience with this problem that has been corrected, if so, please enlighten us...

 

The OP said it the radiator cap.

https://www.jeeppatriot.com/posts/1624561/