Coolant leak.. but where?!

mipa

TJ Enthusiast
Original poster
Joined
Jan 20, 2020
Messages
102
Location
Thailand
Hi,

I've recently bought a new battery including a free install... while doing that, the shop noticed that my coolant was basically empty - no clue how I could miss that. Since I'm in thailand they quickly filled it with tap water.. at least it looked to me like that - I don't speak thai.

The day after I suddenly had steam in my whole car and figured the heater core broke (thanks google and this forum), which also explains where all my coolant went. Since we've an average of 80 degrees here, and therefor I definitely never gonna use the heater, so I used the simple quick-fix and bridged the two hoses with a proper brass fitting (100% no leak there).

While putting the adapter in, I've noticed a ton of gunk and dirt in the hoses, so I decided to flush the system. The last one was probably 10+ years ago from previous owner.. or maybe never. I used a mix of this forum and YouTube tutorials and also changed the thermostat as recommended, while doing it. After cleaning the fittings very smooth, I was very careful in putting the new seal and the thermostat back in, which had glue on one side and felt like a thick piece of paper. I got that, including the new thermostat from a "local" (800 mi away, in Bangkok) original Jeep paarts dealer. I didn't add any RTV or other sealant.

Few days later I found my Jeep parked in a puddle of water, and due to the pink color and no smell figured it's my pink coolant. Also the expansion tank lost about half of it's supposed content below the max marker. The whole oil pan was wet with coolant. I couldn't find a source, so my first guess was that I didn't pull the screws of the thermostat strong enough, so I gave the screws on the thermostat another push - and there was indeed some room for improvement - I don't own a torque wrench.

After that I thought everything would be fine, but today .. probably six weeks later (I don't drive daily).. my Jeep was parked in a puddle of coolant once again... 24h after I drove yesterday. And again the whole oil pan is all soaking wet from the front to the end. With the temperatures here everything dries quit quickly, why I'm surprised to find a wet puddle and a wet oil pan 24h later.

I climbed underneath with a flashlight and I can't explain how the whole pan is wett all over.. not a single dry spot.. even the screws all around have pink coolant on them. I assume it must be drips coming down the front and then get blown along the pan while driving, but again.. its quite hot here.. 24h later that would have been dry I guess. Also around and below the thermostat it's all dry, as far as I can see/reach. But of course the engine is hot, so it probably dries off... but how can it reach the pan then in the first place. It seems to loose coolant once the engine is cold....

Any hints, ideas, suggestions? I could re-do the thermostat and order another seal but I have the feeling that this is not the source.


Thanks for any tips,
Michael

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After I took the pictures of the wet pan and ground and refilled the coolant to the level where it's supposed to be, I drove about 4-5 miles. Now, about an hour later, the pan and ground is all dry and the coolant level is still at the level where I filled it to. As mentioned it seems to only leak when the engine is cold..
 
good point. I just checked again where the water pump is and found that wet spot where water is dripping down right now along the oil pan, while its all dry around the thermostat.

I guess it's likely the water pump then, after 22 years of doing it's service?

Every Jeep part is about 3x the cost here in Thailand, so I try to avoid replacing pieces just in case ;-)

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Order a new water pump and a new thermostat housing from RockAuto - bugger buying it locally from Jeep. Its a pretty simple job to swap them both out and they are dirt cheap to replace. I found that the gasket for my new thermostat housing was crap though, basically it was cardboard and came apart almost immediately after I installed it and started leaking so use some proper RTV - Permatex make one specifically for water pumps and thermo housings.
 
Order a new water pump and a new thermostat housing from RockAuto - bugger buying it locally from Jeep. Its a pretty simple job to swap them both out and they are dirt cheap to replace. I found that the gasket for my new thermostat housing was crap though, basically it was cardboard and came apart almost immediately after I installed it and started leaking so use some proper RTV - Permatex make one specifically for water pumps and thermo housings.

shipping and customs alone is like $200 from the US, so I rather go with Mopar. I plan to replace only the water pump, after some more reading here in the forum, since the thermostat housing seems doing fine... as stated in my update, with a cold engine, I can see now water building up underneath the pump, and dripping down the oil pan, but all dry around the thermostat housing.