Billowing smoke

[Knoxes]

I have about 15K miles on a 4.2ish WJ build.

http://www.jeepstrokers.com/forum/viewt ... f=8&t=3391

It's been running just fine, with some occasional rough idle. Three or four times per year, I use it to pull the Scout trailer (6x9 enclosed - probably 2k lbs loaded) and it's been protesting a bit. It's hard to identify, but it just seems like it's struggling, which it shouldn't be with that load.

So I was about 15 miles down the freeway this time and I noticed quite a bit of smoke when I was coasting down a hill. Coolant temps were fine, oil pressure was good, no CEL's and, other than just not feeling powerful enough, it was running fine. Anyway, I looked things over and couldn't see any obvious issues, so continued down the road for an hour. When I pulled off the freeway, it did the same thing again - huge cloud of (white?) smoke out the back. I swapped the trailer to another vehicle and continued on without a problem.

It doesn't seem to like being locked out of O/D - just emits a heavier whirring sound. But I'm not sure what to make of this situation - transmission problems, or engine issues?

[Cheromaniac]

Sounds like the engine might be burning oil. I suggest you pull the plugs and take a look. Also take a look inside the oil filler cap and check for any emulsion that might indicate coolant entering the crankcase, and check if there's any coolant loss.

[SilverXJ]

From the description of white smoke while coasting down it sounds like its coolant. Verify that it is white. White = coolant, grey= oil, black=fuel.

[Knoxes]

Silver - I'm not following on why it would happen on coasting. Can you explain that?

[jsawduste]

High vacuum

[Knoxes]

High vacuum

Ok, I think it get that, but it's an automatic, so the rpms are relatively low (1300) when coasting.

I was leaning towards a transmission problem after all of today's research, but this is now making more sense. I found some info that lead me to making adjustments in the throttle valve cable to get to the proper shift points. It tends to lug in low rpms and really resist downshift. That was happening quite a bit because it didn't have enough power to stay around 70 mph, but didn't want to downshift when it got in the low 60's, where the rpms are around 17-1800. I thought maybe it was running really rich from a heavy throttle, but low rpms. But then again, it definitely wasn't black smoke....

[SilverXJ]

Could the smoke not be from the engine? Transmission fluid hitting the exhaust maybe?

[Cheromaniac]

Silver - I'm not following on why it would happen on coasting. Can you explain that?

If it's engine oil smoke (typically bluish grey) that you're getting when coasting (high intake manifold vacuum as John mentioned), the likely causes are worn valve stem oil seals or worn valve guides.

[nicpaige]

Sounds like coolant entering the combustion chamber to me through a very small crack or head gasket failure. Check your oil and even if that seems okay send it off to get analyzed.

[Knoxes]

The coolant level hasn't changed a bit since I finished this build in November of 2013. I mean, I know it doesn't take much to make a ton of smoke, but the reserve tank hasn't dropped an 1/8".

There's no sign of a transmission leak either.

And I can't get it to repeat without hooking up the trailer. Without that load, it drives perfectly fine - not a bit of smoke.

[nicpaige]

Rings not seated, pulled a ring land on piston. Pull your plugs.

[Knoxes]

Rings not seated, pulled a ring land on piston. Pull your plugs.

OK, but wouldn't that be noticeable all of the time?

[optmaxx]

I had a leak on the rear seal of the transfer case that connects to the rear drive shaft. It would splash fluid around and some would hit the muffler causing smoke to come out from the rear, but it had a certain smell to it too. I'm just saying without knowing too much about your Jeep.