M38 blowing carbon and liquid from tailpipe

redrad · Post by **redrad** » Sat May 15, 2021 8:32 am

When I start my Jeep up I have noticed water droplets coming from my my tailpipe as well as something spraying about two feet out as well, it’s so noticeable that I have placed a large piece of cardboard to catch this spray so as not to stain the shop floor. Is this common for old L 134 motors or do I need to tweak something?

Post by **wesk** » Sat May 15, 2021 9:33 am

A two foot torch at the tailpipe is not common. Suggested steps are:

1 - Determine the Identity of the material being ejected.

2 - Determine it's source.

3 - Make the needed corrections.

Moisture exiting the tailpipe is not un-common.

RonD2 · Post by **RonD2** » Sat May 15, 2021 12:23 pm

Pretty sure that some condensation (water) out of the tail pipe is normal until the engine gets to operating temp, then it should stop. Modern cars are the same way, more or less depending on ambient temp and humidity. Mine are anyway, especially on the few really cold days in SC. But I think I'd be nervous if it was spitting coolant any time or all the time.

Good luck!

mdainsd · Post by **mdainsd** » Sat May 15, 2021 5:04 pm

If you start it and don't drive it until fully up to temp you can build up water in the muffler. I had the same issue when i finished the rebuild of the motor in my M38, black dirty droplets and lots of water vapor. I was thinking I must have messed up the head gasket somehow. Lots of starting the jeep to finish and test systems. I was talking to a friend that I was thinking needing to pull the head. He said for me to drill a 1/16" hole in the bottom of the muffler. I was surprised when more than a quart of black rusty water drained out of the muffler. Instant fix, no more vapor and no more black muck..

The muffler did rust out two years later, so I guess the damage had been done.

redrad · Post by **redrad** » Sun May 16, 2021 7:00 am

Thanks for all the reply’s, I started the Jeep and caught the water droplets mixed with black spots in a milk jug, then took it on a ride around the neighborhood till it was completely warmed up, the rechecked the exhaust again this time no water, since this Jeep set up for 10 years I am guessing some build up of crude in the exhaust system, I will just keep driving at least once a week to keep it in good operating condition.

mdainsd · Post by **mdainsd** » Sun May 16, 2021 10:28 am

Around the neighborhood usually isn't good enough. A good ten or fifteen mile drive with decent speed and some hills is what it takes to get everything up to a good operating temperature and remove all water in the system.