Strange white smoke exhaust

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

missouritig

OBS Enthusiast
Joined
Sep 8, 2022
Messages
62
Reaction score
61
Location
Missouri
2000 k3500 5.7 auto 4x4 280k miles

Not entirely sure whats going on.

I have zero trouble codes, engine sounds good. I have no history, it was probably a 5th wheel ferry for a local tractor shop, so it was probably run ragged.

Lots of white puffy steam coming from exhaust. Smells gasoliney. My dipstick oil looks very clean and level is good. My coolant level is good. I tested this out at idle and put a large cup under my exhaust pipe. It collected quite a bit of condensation, like I should be bone dry on coolant but the level is all good.

Only issue im having that is noticeable is I cant get my coolant up beyond 160'. It was very cold out today, but puttering around the farm it would drop to 120's once I stop. I am thinking my thermostat is stuck open.

Is it possible this is just a air/fuel mix issue causing massive condensation due to me constantly running in open loop? I am suspecting at least one bad pre-cat oxygen sensor due to having a partially melted harness. I am thinking this is not tripping a engine code.
 

tayto

I'm Awesome
Joined
Nov 11, 2020
Messages
724
Reaction score
762
Location
Canada
water is a biproduct of combustion. yes, i would start with replacing the thermostat. i just fixed a truck like this, smelled really stinky (unburned fuel) & wasnt getting up to temp. new thermostat fixed it.
 

Scottm

I'm Awesome
Joined
Aug 24, 2021
Messages
283
Reaction score
219
Location
AZ
It sounds like a bad head gasket to me. White smoke means burning antifreeze. You might see bubbles in the coolant with the engine idling and rad cap off, but it might also require a leakdown test to be sure.
 

Schurkey

Supporting Member
Supporting Member
Joined
Jan 14, 2018
Messages
10,970
Reaction score
13,756
Location
The Seasonally Frozen Wastelands
Every fall when the weather turns colder, the vehicles around here blow white smoke until they've been driven long enough to heat the exhaust system so the water vapor from combustion isn't condensing in the pipes.

Common as dirt. Doesn't require a head gasket leak/coolant in the combustion chambers.

Install a functional thermostat, see what happens--ESPECIALLY after you've driven ~20 miles. Wouldn't hurt to connect a scan tool, verify the coolant temp sensor; and of course replace O2 sensors as needed (which is probably ALL of them.)
 

PlayingWithTBI

2022 Truck of the Year
Supporting Member
Joined
Jan 3, 2019
Messages
9,552
Reaction score
14,679
Location
Tonopah, AZ
Wouldn't hurt to connect a scan tool, verify the coolant temp sensor
Yep, check to make sure your ground wires at the T-Stat are connected properly so, your PCM sees the correct temperature. Otherwise it'll throw all kind of gas at it and create white smoke. Not all white smoke is from burning coolant.
 

missouritig

OBS Enthusiast
Joined
Sep 8, 2022
Messages
62
Reaction score
61
Location
Missouri
Replaced thermostat with a oe 195' style and truck went right to temp and then went down as expected. That was even in 15 degree weather today, so thats good! Truck has some maybe odd fuel trims. Im going to do a fuel and cylinder compression test once it warms up later, still either is dumping fuel or coolant out exhaust. Im leaning on fuel at the moment due to fuel odor in engine bay
 

Schurkey

Supporting Member
Supporting Member
Joined
Jan 14, 2018
Messages
10,970
Reaction score
13,756
Location
The Seasonally Frozen Wastelands
Run the truck long enough for the computer to adjust to being at proper temperature.

And are the O2 sensors working properly? I'm moderately sure I replaced the original O2 sensors (all four) on my '97 at ~170K miles. Some folks just don't "get" how important they are; and how seized they can be when ignored for too long.

The engine has been run cold, and with a failed O2 sensor. Good chance that the catalyst(s) are damaged. So again...run that thing long enough to get EVERYTHING warmed-up. Maybe the catalyst(s) can come back to life again.
 

missouritig

OBS Enthusiast
Joined
Sep 8, 2022
Messages
62
Reaction score
61
Location
Missouri
Replaced the two before - cat o2 sensors. They were just charcoal black but not plugged. Looked like Bosch variety. Not seeing any signs of coolant so far

I had less white smoke after letting it run but still smells a little rich. The voltages look a lot more consistent.

Will do a fuel pressure test later once I can actually drive and see if it self corrects. Getting front suspension redone and also finally fixed the shifter so it goes from P to 1 just fine!
 

missouritig

OBS Enthusiast
Joined
Sep 8, 2022
Messages
62
Reaction score
61
Location
Missouri
Well now im a little more confused.

I drained about 7 gallons out the tank after disconnecting the fuel filter, with the intention of replacing it with fresh and then replaced the filter. I still have some fuel in the tank but not sure how much, its got to be close to empty. Drove the truck around for about 45 minutes and not one bit of steam came out the tailpipe.

it was warm out today but I know I drove it before in warm weather and had tons of steam coming out a few months ago.

Im going to throw my hat on a bad fuel filter and perhaps some bad gas?
 

Erik the Awful

Supporting Member
Supporting Member
Joined
Aug 9, 2019
Messages
7,614
Reaction score
15,528
Location
Choctaw, OK
Lots of white puffy steam coming from exhaust. Smells gasoliney.
If it were a coolant leak it would smell sickly sweet. I think you were just burning off some condensation. I wouldn't worry about it unless there's some other evidence of a malfunction, like a coolant smell, or smoke so thick the car behind you can't see, or misfiring.
 
Top