Bigandyfasho

ok so I'm new to this but I have a 95 Jeep Grand Cherokee 4.0 inline six with an automatic. I had some heating issues and I replaced the entire coolant system, fuel pump, fuel filter, and flushed all the fluids. I checked the oil and it's not milky, and it fires up without an issue but the motor blows white smoke. I start it up and within a few seconds white smoke starts coming from the engine. I can't figure out what's going on.

thatXJguy

Did it do this before you did the cooling system upgrade?

Cherokee_Mike

White smoke sounds like auto gearbox fluid being burnt in the engine ?
Do these auto gearboxes have a vacuum module ?
The diaphragm can develop a pinhole and the engine can suck the fluid out on gearboxes which have these modules.
Check your gearbox fluid level as a precaution.

dave1123

No, there's no vacuum going to the transmissions on jeeps. Is it possible someone put diesel in the fuel tank? Kerosene will produce lots of white smoke when ignited by a spark plug.

PCO6

Following this for interest. I have a similar problem. I'm currently replacing the floors in my '95 XJ and the gas tank is out for safety reasons while welding. I figured I could also use the time to figure out what the engine problem is! It runs great but there is a slight trace of white smoke while it is running.

The engine runs strong. Compression is good (I need to do a leak down test). All fluid levels are up and they're clean. There's no trace of water in the oil. I'm thinking (hoping) that there may be some water/condensation in the gas tank and that flushing it before I reinstall it will solve the problem.

dave1123

Another thought just hit me for both you guys. How about bad valve stem seals. When that starts, it shows a little white or bluish smoke at idle or decelerating. It turns blue when it gets really bad, but doesn't show up on acceleration, only when vacuum is high.

PCO6

Thanks Dave. I thought of that too. Unfortunately my XJ was off the road when the problem occurred and I couldn't test acceleration, etc. I had also just redone my cooling system (like the OP) and I can't see where the correlation might be. My smoke is white and it's very faint.

Next up is to finish welding in the cargo area floor then install the gas tank so I can get it running and test the engine. I'm hoping fresh gas and a valve additive might do the trick. I also need to go over the entire vacuum system. I don't think it will come to this but a new stroker engine will probably cure the problem ... and I'll do whatever I have to do! (lol)

dave1123

Okay, a little backstory as to why I thought of the valve seals. My 4.0 had been using about a quart of oil in 2000 miles before the head cracked. It had 179,000 miles on it then. It had a slight valve cover and oil pan gasket leak. I bought a "Clearwater" head to replace the cracked 0331. The valve cover leak was fixed then and the oil pan leak was only a wetness without any dripping and the rear main was dry, so I let it go because of the cash I spent replacing the head. The oil usage got worse, to about a quart in 1000 miles! I figured it was just a new head with good valves placed on top of worn rings, so what did I expect? I checked the compression and it was above normal with a little grey ash on the plugs and no blowby and no smoke under power. I had a noticeable blue smoke after idling a while and the oil usage continued to get worse. At 203,000 miles it was using a quart in 250 miles, so I decided to replace the valve seals. They were hard and had minuet cracks on the sliding seal areas. Apparently "Clearwater" had used NOS seals, not fresh ones! Now my oil usage is around a quart in 750 miles. I'm still trying to figure out where the rest of it is going. Maybe the oil pan leak is worse than I thought. The oil smoke is gone now. It took a while for the converters to burn themselves clear.

The moral of this story is don't trust anything you buy already assembled without checking the parts yourself. You shouldn't have to, but that's the way it is now. This is why I'm reluctant to buy a rebuilt engine. I'd rather do it myself. Trust, but verify!

peep

When you start up and blow white smoke, is the exterior temperature cool or cold, is it humid outside.
Generally smokes: White -water condensate in exhaust system, if your oil is alo turning to crappy tan milkshake then water/coolant is leaking into a cylinder and past piston contaminating the oil, will lead to premature bearing wear and failure. At start up, is ok, all the time is not good.
blue - oil burning in combustion chamber, generally a worn valve seal(s) and/or piston ring, if only at start up, generally valve seals, if all the time, piston oil ring worn out.
black - fuel, too much fuel, rich condition, ok at cold start up but should not be all the time, can be from poor ignition and poor combustion conditions.

Bigandyfasho

It ran fine without any smoke up until i finished replacing the coolant system. I did the entire system and about 2 weeks later my thermostat stoped working again. It wouldn't open at its normal spot and the temp started to climb really fast so I shut it off and went and and got another with a gasket. Replaced the thermostat and checked my fluids and they all were at good levels (oil needs to be changed here soon but it's not milky) and I topped of my transmission fluid when I replaced the radiator a couple weeks ago. After the thermostat was replaced i let it run for about 30 mins without any issues, no smoking, no odd noises, no raising temp. I had a weird gut feeling to fire it up and let it run for longer and take it for a test spin and triple check and that's when it started smoking (white) immediately at start up from the motor itself. I was thinking maybe the rings are bad?!?

In all I've replaced the fuel pump/ filter
Crank shaft pulley
Serpentine belt
Battery
Plugs and wires
ECU
Entire coolant system
Replaced fuses

Bigandyfasho

And it's been really cold and wet outside and the jeeps been outside for the past couple weeks.

peep

Puzzeling.
Bad rings? Usually lead to oil consumption and produce blue smoke.
White is water vapour. Is your coolant level depleting, does the smoke continue after warm up. It will continue if it is cold outside.

dave1123

Wait....you said "from the motor itself." You don't mean from the tailpipe?

Bigandyfasho

Yeah it's coming from the motor and its white. I'll start it up tomorrow when I go to work and run it for a few mins and see what happens. At this point I just wanna move it without getting a tow and if driving it will damage it more with bad rings.

dave1123

All I can think of is if you soaked the exhaust manifolds with oil or solvent, it'll just have to burn off. Try letting it run for a while, but watch the temperature and oil pressure. Don't drive it because you don't want it to die on the street.