What does the exhaust tell you?

[inyati13]

I have a Cat D3G 2005 dozer. It is running well. However, on start up the smoke exhaust is white and smells bad until it warms up. Then sometimes even after it has worked, it will exhaust white smoke when you throttle down. What does the white smoke say about engine conditions? The engine exhaust is clear and odorless except for the odd event I mention.

 

[stumpjumper83]

hummm... hows the antifreeze level?

 

[DirectTech]

If it smells like unburt diesel and burns your eyes it could be an injector that is not atomizing porperly, or as stumpjumper said it could be antifreeze.

 

[SE-Ia Cowman]

white smoke is also a sign of low compression.

 

[jrtraderny]

I gotta lean towards a leaky head gasket

 

[GCC]

how many hours are on the motor could be leaky injector or dried valves, wore rings. i would try the balloon trick first and see if its an injector its pretty easy to do remove the left side engine cover get some small elastics and a couple balloons. remove your injector lines at your injector then put a ballooon over the end of each injector then use the elastic to wrap around a couple times to keep it on there can use small hose clamps to then roll your motor over a couple times. if any of the balloons fill up at all the injector needs to be rebuilt it not sealing properly hope this helps. if that doesnt work you can pull a glow plug out take it to lowe's, home depot and find your thread size and and make a custom fitting to go in where the glow plugs do and test each cylinder and see what your compression is. also well machine is running look in your rad once you start it and rev it a couple times and see if you see any bubbleing in your rad check when hot to give it a couple revs, if there is bubbleing follow through with the compression test you have a bad head gasket or you dont even wanna think of this one possible a slight hair line crack in your block i could imagine it being a crack it usually a lot worse hope all this helped you

 

[John C.]

If this is a "G" series, there are no glow plugs.

On start up the engine will be down on compression some which will seal up as the engine warms up. It is not unusual to see the smoke for five or ten minutes after startup. The white smoke on deceleration though is a little odd. If your air filter is reasonably clean then I would think that more than likely you have some leaky injectors. How is the fuel usage?

 

[d9gdon]

First thing I would look at after checking to see if it's a head gasket is the supply line from the fuel tank. Those G series liked to stop up with trash in an elbow right before the water separator. I think they put a little electric primer pump on the later models. You should be able to tell the difference in the smell of the smoke whether it's burning antifreeze or if its a fuel problem. Antifreeze has a slight sweet smell to it, lean fuel condition will sting your eyes.

I think you've got cylinder head or gasket problems though. Those Mitsubishi engines don't like to run hot according to my dealer's tech rep and it's a must to pull the radiator to clean thoroughly if you run in trashy dusty situations like land clearing when you can no longer get it to run cool by blowing it out. I know from my own experience with a couple of D4G's.

 

[CAT793]

Sounds like Fuel Timing (Start with Pinning the Cam/Flywheel).

Previous suggestion of Fuel Restriction rings true too. Not enough fuel causes incorrect Fill Rate and effectively retards Injection timing.

If it has External Fuel Lines to each Injector crack each Fuel Line while it is smoky and see if an individual Cylinder reduces smoke. If it is a EUI Motor with common Fuel Rail use CAT ET to drop pots with the same result.

Good Luck!

 

[inyati13]

Thanks to all. Here is answers to some of the questions. Has about 1900 hours. The antifreeze level is fine and the has never been a need to add over the past year. There is not a single leak spot around the engine in except for dust which I blow off on a regular basis, it looks new. Oil pressure stays at about 40 pounds, or middle of guage. White smoke is infrequent. The bad smell is on start-up and since it stays in a tight metal building it does burn your eyes after about 5 minutes. There are not glow plugs on the G series. It has a pre-intake air heater. Always starts immediately even at 10 degrees F. The white smoke rarely occurs after warm up. But it has happens a couple of times. I have also had some debris in the fuel take. I had it the tank cleaned and vaccumed out. That seems to have helped. Before that the fuel/water separator was stopping up. There is no water from the water/sediment drain under the tank but the is still and small amount od debris.

 

[inyati13]

Oh, but the way fuel is low! Sorry for the mistakes in the previous post. I am in a hurry this morning. After reading the responses, I wonder if the fuel water separator filter is still getting stopped up. I have not changed it in a while since I thought that problem was solved. That would say I may still be staving for fuel!

 

[inyati13]

Have been thinking (dangerous for me). At first start, I warm up at the lowest govenor position and mine is set low. Should I be warming up at a little higher fuel input to prevent too much fuel restriciton?

 

[d9gdon]

You've definitely got fuel restriction then. Change the separator often. Even if you don't see but a trace of water in the glass bowl, I always had better luck running a little bit of fuel additive in mine that got rid of the water. Don't know why, but those G's seemed to always have a bit of water show up in the separator. I guess from condensation in the fuel tank. And it's beyond me how the debris gets in the fuel tanks either. I've found big chunks of oak bark in the line before. Got a feeling my operators were taking the screen out when they were refueling so that the filler nozzle would stay in the neck.

Also, if you're running on a slope with low fuel you're asking for trouble as far as sucking air.

Take that supply line loose from the separator and see what kind of dribble you're getting. You should be getting a very nice flow.

 

[inyati13]

You've definitely got fuel restriction then. Change the separator often. Even if you don't see but a trace of water in the glass bowl, I always had better luck running a little bit of fuel additive in mine that got rid of the water. Don't know why, but those G's seemed to always have a bit of water show up in the separator. I guess from condensation in the fuel tank. And it's beyond me how the debris gets in the fuel tanks either. I've found big chunks of oak bark in the line before. Got a feeling my operators were taking the screen out when they were refueling so that the filler nozzle would stay in the neck.

Also, if you're running on a slope with low fuel you're asking for trouble as far as sucking air.

Take that supply line loose from the separator and see what kind of dribble you're getting. You should be getting a very nice flow.

Will do. Thanks