Start Up Smoke

Joe1 · Jul 12, 2005

I have a 1998 John Deere 770 with 366 hrs. I purchased it two years ago with 223 hours. I've serviced it regularly, and changed the oil and filter and fuel filter at 325 hours.

Lately, when starting it, it will put out some black smoke from the stack, and also when reving up quickly from idle, it will also put out some smoke. This seems to be just since about the time of the last oil change. I just checked the oil, and with 41 hrs since being changed, it has not dropped on the dip stick, so I know it's not burning oil.

I use the recommended John Deere oil of the correct weight and use John Deere oil and fuel filters. I only burn high quality off road diesel.

The tractor starts instantly and runs perfectly, with no hint of hesitation or of running hot. After the initial shot of smoke that only lasts a second, it runs cleanly with no visible smoke.

(1) Is the smoke possibly because the injectors are getting dirty, and if so, would a diesel injector cleaner fuel additive help?

(2) Is this "normal" and maybe I just didn't notice it before, which I tend to doubt?

(3) The only thing I have not serviced (since it was done at 200 hrs and is not due until 400 hrs) is the air filter. Could a clogged air filter have anything to do with this? I tend to think not since it runs so strongly.

(4) Am I worrying for nothing?

Any info would be appreciated.

Joe

BigAl · Jul 12, 2005

Joe
It could very likely be that air cleaner . I assume you have been cleaning the air filter and blowing it out on a regular basis ? I would change it even though the hours are not up. A dirty filter can cause black smoke .If you have been working in high dust conditions it should be changed . It could also be injectors as you say ,and you might want to add a bottle of injector cleaner to your fuel ,but I suspect the air filter and would try that first . Let us know what you find .
Allen

Joe1 · Jul 12, 2005

BigAl:

I have been bush hogging and it's raised a lot of dust and pollen. I think that a filter change is in order.

bczoom · Jul 12, 2005

Joe,

If I recall correctly, you're not supposed to attempt to clean the inner filter. I would clean the outer filter but leave the inside one alone if clean (replace if dirty).

Actually, #'s 2 and 4 of your original post are probably the most accurate after you clean the exterior air filter.

Brian

Hypernix · Jul 12, 2005

( Lately, when starting it, it will put out some black smoke from the stack, and also when reving up quickly from idle, it will also put out some smoke. This seems to be just since about the time of the last oil change. I just checked the oil, and with 41 hrs since being changed, it has not dropped on the dip stick, so I know it's not burning oil.
)

Joe1,

I'm far from being an expert on the matter but my 4110 with 100hrs does exactly the same thing. I'm thinking it's normal. I haven't noticed any other problems with the tractor yet.

Hypernix

bigpete · Jul 12, 2005

Ditto. I understand the start-up and throttle-up smoke to be sooty exhaust caused by partially burned/unburned fuel that has been injected into the combustion chamber at a volume greater than the lagging engine can burn. The way I (also) understand the smoke issue is that prolonged smoke from a warmed engine, or smoke under no load or light load at a constant RPM, is an indicator of a problem--rings, injectors, etc..

Edit:

 (1) Is the smoke possibly because the injectors are getting dirty, and if so, would a diesel injector cleaner fuel additive help? Possibly. Don't know if the additive would help 

(2) Is this "normal" and maybe I just didn't notice it before, which I tend to doubt? Normal for a maturing engine, most likely 

(3) The only thing I have not serviced (since it was done at 200 hrs and is not due until 400 hrs) is the air filter. Could a clogged air filter have anything to do with this? I tend to think not since it runs so strongly. I would change it to see 

(4) Am I worrying for nothing? No. You worry because you care. Most people like to buy used equipment from people who have worried

Joe1 · Jul 13, 2005

I acquired the parts for the air filter, and when I looked at my manual again today, I noted in the trouble shooting section that a dirty air filter could cause the smoke. The JD dealer also sent me a Diesel Injection shop, and they sold me an additive that should help as well. Can't hurt.

thanks for the advice.

SteveH_CT · Jul 13, 2005

I think you'll find it's better when you change the air filter. I recently changed mine while I did the oil change. The start-up smoke is almost completely, or completely gone - certainly not enough smoke to notice.

BTW - mine had the same symptoms as yours - the smoke at start or a quick jump in throttle, with no noticeable drop in oil level ever.

Good Luck!

goodolboy · Jul 13, 2005

Black smoke is too much fuel / not enough air. Sounds like you may be on the right track with the airfilter. Black smoke is the result of incomplete combustion.

DennoAce · Jul 16, 2005

A quick puff of black smoke is perfectly normal for a diesel when giving a quick burst of fuel (flooring the throttle), since the injection pump is right there with the fuel but the RPM of the engine is not up to snuff to properly compress the extra fuel yet. As long as it goes away immediately, this is how it is. Same thing when you bog a diesel down quickly it will smoke briefly...it has too much fuel and not enough RPM.
Of course, the older everything gets, the more this will happen since tolerances are opening up.
Of course, changing the air filter is a good thing as she does need a lot of air and this certainly could be part of it too, and you NEVER clean a "safety" (the little one) air filter. If it dirty at all, I would replace it.

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