Zorba's JeepThe thermostat housing was replaced by the dealer a few days after I bought the Jeep. There's been a troublesome very slow coolant leak ever since. It finally got bad enough that I could see the coolant on top of the water pump, which means it could only be coming from the thermostat housing. R&Red it, installing a new Felpro gasket. Unfortunately, this did NOT stop the leak.
Thermostat Housing Gasket
Backup lite LEDs.
Coolant on TOP of the water pump, only one place it could come from.
Removed the thermostat housing and cleaned the mating surfaces.
New Felpro gasket
A closer look at the mating surface on the front of the head. See text.
It would appear that the leak is drastically slowed, but apparently not stopped completely. The above picture shows two possibilities. The green circle area shows a bit of old gasket which may or may not have been removed after that picture was taken. The red circle shows an area which is proud of the rest of the flange. Its obviously supposed to go into the cut-out in both the gasket and the thermostat housing - although why its made that way Goddess only knows. However, its also possible that its wider than it should be and/or the aftermarket thermostat housing doesn't allow sufficient room for it. I've read where some aftermarket thermostat housings have inexplicable leaks - and this may be why. I over-tightened the bolts from the spec 20 nM to 25 nM to see if the leak would stop. It didn't.
FAILSo the second attempt to get this to stop was a bit more comprehensive. The dealer from whom I purchased the Jeep about 21 months ago had installed this thermostat housing, and I've always had a slow leak. After I changed the failed water pump, I found this leak per the above (top of page) photo. I did a coplanarity check on this aftermarket housing. It appears to have a problem in this area, the best I could tell from the tools at hand. This certainly could cause the leak I'm seeing. In addition, the "Green circle" in the above photograph showed a bit of old gasket that I didn't know if I had removed it or not the first time. It turns out that I had not. However, this really shouldn't have caused this problem as it was ultra thin, but I got it removed this time around anyway. As for the "Red circle" in the above picture, I don't know if that proud metal is contributing to the problem or not. My crude check seems to indicate not, but I'm not sure. In any event, Permatex to the rescue! I've fixed lots of goofy problems like this over the years using this "miracle product", hopefully this will be yet another. I was able to get a "click" when rocking the housing on a flat - but hardly NIST traceable - reference surface so coplanarity certainly seems to be off, so fingers crossed! If this doesn't work, I'm going to have to source yet another new thermostat housing, and I'll insist on a genuine MOPAR!
Drain a gallon or so of coolant out AGAIN...
YANG - Yet Another New Gasket, with a tube of Permatex...
Thermostat housing. Note some roughness. See text.
Checking bolt holes to see if they go through to the coolant passage...
...Nope. Only "that" deep. Blind hole - not the source of the leak.
Thermostat housing slathered with Permatex.
Gasket put on, block side of gasket also slathered.
Bolted back on.
Belts and hoses reattached.
Oh, and just to add to the fun, I got the whole thing together, then realized that I hadn't reinstalled the thermostat. Thank Goddess Permatex sets up slowly...
A guy on the Jeep forum started making these for anyone who wanted them - at $30/pair shipped! Couldn't pass it up. Extension cable locks into the existing backup bulb socket, and the heat sink of the triple LED assembly screws onto the metal baffle between the backup and tail lites. Its hard to see in the above pix because I had previously added some reflective tape to the insides of the tail lites, including the baffles - BUT - there is a stiffening rib pressed into the rather thin metal. On this Jeep, the rib was oriented upwards, but I swapped the baffle around to point the rib downwards so the LED assembly would have a flat surface to mount to. No other differences noted from this reversal. Oh, and the supplied 6d nail is now in my nail box, waiting to be re-used!
After a 50+ mile drive, and an overnite cooldown, no coolant leak seems to be evident. I'm cautiously optimistic that this damn thing is now fixed!
New backup LEDs
Custom triple backup LEDs from guy on Jeep forum.
He even included a 6d nail to mark the drill locations.
Mounts on this pre-existing baffle.
Stiffening rib oriented downwards. See text.
These backup lites are BRITE! I had previously replaced the stock incandescent bulbs with LED bulbs with a substantial improvement - but this setup is a couple or three orders of magnitude better than even that - according to my "calibrated eyeball." The LED bulbs thus removed are going to go into the old Mercedes, which is still running incandescent backup lites.
Another Jeep next to me at "Homeless Despot".
Read on for the next part!