Engine smoking, I assumed it was a coolant leak as there are so many videos about replacing water pumps and thermo housings. I just ran coolant pressure test and unless I did it wrong (first time), it held 10 minutes plus at 17 psi (cap says 18) but wanted to be a little careful (see pics). Tested cap as well (no pic) that held at 18. The only thing I noticed is the transmission line going into radiator has a drop of trans fluid hanging from it (pic from above, but you can see the PO tightened the heck out of it). So it's not dripping when car is cold, but have to assume it does more when hot. I looked at oil, perfect, no milk. I check trans fluid level (cold) which I know isn't the right way but really didn't want to start it up until I could figure it out. Plenty of fluid on the stick. I can easily change that trans fluid line just not confident that's the cause. Any other ideas? Appreciate the help as always.
Engine Smoke: Coolant or Transmission Fluid?
- Thread starter Lucky!
- Start date
I've seen head gaskets hold pretty well until they heat up. Same with cracked heads.
How many miles on that 04?
-Mac
How many miles on that 04?
-Mac
Thanks Mac. 147K, I replaced head gasket in Sept because it was leaking pretty good closer to the body. Just checked around it, still looks pretty clean. I added two more pics. The first is the new coolant housing, I installed a month or so ago, no leaks around it but the second pic by the old water pump you can see the white flakes all over it which is why I thought it was a coolant issue. But the pressure test holding is throwing me off.
Last edited:
KennethS
TJ Addict
Through the transmission vacuum modulator, maybe? (if it has one - mine is manual so no idea on the automatics). But that would smoke out the exhaust and not under the hood.
He was referring to the head gasket not the rocker cover gasket. As Mac stated "head gaskets hold pretty well until they heat up" so you might try re-testing a warmed up coolant system..
Thanks for the tweak. Not sure why I went to the valve cover when I read head gasket. I'll drive it around in the morning and retest.
Did you put sealant on that front head bolt by the thermostat housing?
It goes into the water jacket.
It goes into the water jacket.
KennethS
TJ Addict
Found the Ford guy.
The automatics in the TJ don't have a vacuum modulator.
GM, not Ford. As I said, my Jeep has a MT.
Last edited:
We have a winner! Brought the Jeep up to temp, then pressure tested. The pressure went down slightly over time, but no apparent leaks. So we ran the engine until it started smoking to see if we could find it. Culprit is one of the transmission lines has been rubbing on one of the upper cats. When the engine warms up the transmission line is expanding and fluid is dripping onto the cat and then down on the exhaust pipe next to the oil pan and smoking. My assumption is that when I had the motor mounts replaced about 6 months ago they moved some of the lines around and didn't see it rubbing against the cat. Next step is researching how to replace the lines. Appreciate everyone's input. Now the fun begins.
Similar threads
