Diesel smoke questions? Read this first! (1 Viewer)

[tcurrie]

I have mensioned this in a previous post but I thought id start a thread specificaly for this.

My 81 will start to puff quite a bit of blue smoke only after extended periods of low idle like when I am out hunting and crawling slowly along logging roads. This is the only time it ever blows blue. If I rev the engine up, it goes away quickly. It dose not seem to use oil. After 6000kms it still has 3/4 on the dip stick

Any Ideas as to what might be causing this?

 

[Splittilps]

Don't have an answer but mine is the same. i don't think is anything to worry about. It got allot better after i started to use Howes in every tank.

cheers

 

[roscoFJ73]

Probably a bit of oil leaking down the valve guide seals.

 

[canadian bum]

Diesels natrually don't like to idle for long periods of time. Thats why if your going to let it idle there is a high idle on big truck engines anyways as well as a pull throttle on cruisers. Anyways a little oil just gets into the cylinder from idling for so long and causes the blue smoke. It maybe caused more so by having cooler combustion temps since the engine is not working hard and the RPM's are low further contributing to lower temps.

 

[tcurrie]

Well it sound normal then so I wont worry about it too much. Thanks all for the input.

 

[canucksafari]

Well it sound normal then so I wont worry about it too much. Thanks all for the input.

Its normal for engines with worn valve guide seals but it isn't normal. It won't hurt anything as long as you keep an eye on your oil level. IMO, the best thing is always to replace worn parts. The valve guide seals usually are not expensive. It's just expensive if you have to pay someone to replace them.

 

[Greg_B]

Canadian Bum has a good explanation.

In addition, there is a term called "loading up". Older diesels where the fuel delivery is not computer controlled are more prone to loading up at idle, but they can all do it. The 1st good throttle application will give that puff of white/blue and clean it out.

Don't excessive idle the engine. Look up the term "diesel glazing cylinder walls" in Google.

Elevation will make this more noticeable too.

 

[tcurrie]

Its normal for engines with worn valve guide seals but it isn't normal. It won't hurt anything as long as you keep an eye on your oil level. IMO, the best thing is always to replace worn parts. The valve guide seals usually are not expensive. It's just expensive if you have to pay someone to replace them.

Any idea for an approx. cost to have then done?

 

[tcurrie]

Canadian Bum has a good explanation.

In addition, there is a term called "loading up". Older diesels where the fuel delivery is not computer controlled are more prone to loading up at idle, but they can all do it. The 1st good throttle application will give that puff of white/blue and clean it out.

Don't excessive idle the engine. Look up the term "diesel glazing cylinder walls" in Google.

Elevation will make this more noticeable too.

Thanks, thats intresting. I guess it would be better to put her in low range in a 1st or 2nd gear and keep the RPMs up a bit when crawling along...what do you think?

 

[tcurrie]

I was just thinking about it some more and realized something else.

I often will start my truck 20 to 30 mins before going to work and I have never seen it puff blue as long as it has been idleing in PARK and under no load. It puffs blue only when the engine is in gear, under load, and low RPMs for an extended period of time.

Dose that angle change anyones valve seal diagnosis at all?

 

[canucksafari]

Underloaded for me would mean driving on the flat or going up a hill. I would expect it to burn oil at higher RPM is it was the oil rings. How much oil you going through in 5000 kms?

Did you check the intake from the turbo?

Lastly, are you sure it is motor oil smoke?

 

[lostmarbles]

I'm interested in the comments about prolonged idling being bad.

Diesel cruisers have been the "vehicles of choice" for roadside-weedspraying here for years. (Not so much nowadays though because they have become pretty well "priced off the market".)

And "idling" represents 90% of the mileage/engine-hours of such vehicles.



PS. I've never worried about getting out of my vehicle (to check a river crossing or whatever) and leaving it idling. - Although I admit I often pull the hand-throttle slightly to increase the RPM.

 

[tcurrie]

Underloaded for me would mean driving on the flat or going up a hill. I would expect it to burn oil at higher RPM is it was the oil rings. How much oil you going through in 5000 kms?

Did you check the intake from the turbo?

Lastly, are you sure it is motor oil smoke?

I still have about three quarters showing on the dipstick after 6000 kms.

I have not checked the intake from the turbo.

I assumed since it was blue that it was oil. could it be something else? I know that there are at least three valves that need to be adjusted....could that have something to do with it?

 

[canucksafari]

If it is burning oil, it isn't much in 6,000 kms - only down 250 ml. My wife's Tercel eats in a week.

To confirm it is motor oil burning get someone to drive behind yourrig who knows what the smell of burnt engine oil smells like. If it smells like unburnt diesel, then the cause of your smoke is elsewhere.

If it is burnt motor oil smoke, you might try some of the engine purge additives that Greg recommended in the last couple weeks. At 6,000 kms in an indirect injection engine you are due for an oil change anyways. Not sure what the interval is for a direction injection engine like yours.

 

[Greg_B]

I'm interested in the comments about prolonged idling being bad.

Diesel cruisers have been the "vehicles of choice" for roadside-weedspraying here for years. (Not so much nowadays though because they have become pretty well "priced off the market".)

And "idling" represents 90% of the mileage/engine-hours of such vehicles.



PS. I've never worried about getting out of my vehicle (to check a river crossing or whatever) and leaving it idling. - Although I admit I often pull the hand-throttle slightly to increase the RPM.

Statistical proof because I'm a papered mechanic with 1000 rebuilds under my sleeve and the laboratory in the back room. Nope, not me.

The HD mechanics at work have mentioned this, and have asked we put the trucks on high idle when parked at an incident. This is for electrical load concerns as well.

From conversations with diesel mechanics, as I pick their brains.

Filtered through reading and research.

I bump the idle too when wheeling and stopped for whatever reason (when I remember), and I would not turn it off simply to get out and check something. I understand "excessive" to mean hours and hours.

TheDieselStop.Com - www.thedieselstop.com

http://www.wjwatson.com/files/runningin.pdf (diesel generator info)

Get past the marketing, there is some good information...from your neck of the woods: Colour of engine smoke and when it occurs tells about internal condition

Marine diesel engines: maintenance ... - Google Book Search

Piston glazing and your "modern" diesel - Australian Land Rover Owners

Tonnes more out there if you want to read...








And...

Scary stuff here: Diesel Talk Forums - Glazing of cylinders read the de-glazing post. Yikes!

 

[Greg_B]

Thanks, thats intresting. I guess it would be better to put her in low range in a 1st or 2nd gear and keep the RPMs up a bit when crawling along...what do you think?

Probably. How's that for definitive!

 

[Greg_B]

There's been a lot of questions over the years about diesel smoke, and what the different colors mean. There have been some good data and input from different members.

Maybe the mods can look at diesel smoke FAQ.

Here is the main data from the NZ link, without the hyperlinks. I think it jives with what some of the more experienced and knowledgeable folks have mentioned. What do ya'll think.


SMOKE COLOUR

Basically there are 3 types of smoke emitted from a diesel engine: black, blue and white.

Black smoke:

Black smoke is the most common emitted from diesel engines and indicates incomplete combustion of the fuel. Black smoke causes can vary widely and include ..
· Incorrect fuel injection timing
· Dirty or worn fuel injectors
· Over fuelling
· Faulty turbocharger, or turbo lag
· Faulty or dirty exhaust gas recycling (EGR) system
· Incorrect valve clearance
· Incorrect fuel to air ratio
· Dirty or restricted air cleaner systems
· Over loading the engine
· Poor fuel quality
· Cool operating temperatures
· High altitude operation
· Excessive carbon build-up in combustion and exhaust spaces

Black smoke can occur across the entire operating range, but is usually worst under full power, or during the lag before the turbocharger boosts air supply to match the fuel usage such as in the early stages of acceleration and during gear changes. Moderate turbo lag smoke is acceptable; otherwise black smoke should be hardly visible in a correctly running engine.

Blue smoke:

Blue smoke is caused by engine lubricating oil burning. The oil can enter the combustion chamber from several sources including:

· Worn valve guides, or seals
· Cylinder &/or piston ring wear
· Cylinder glaze
· Piston ring sticking
· Incorrect grade of oil .. too thin and getting past rings, or valves guides
· Fuel dilution of the oil, making it too thin.

Blue smoke is often evident at cold start, which can reflect reduced oil control due to carbon fouling deposits around the piston rings and/or cylinder glaze. Blue smoke should not be evident at any stage.
An engine may burn oil without the evidence of blue smoke, because good compression burns oil quite cleanly, however, it is not acceptable for any new engine, or engine in good internal condition to burn large amounts of lubricating oil.

White smoke:

White smoke is caused by raw, un-burnt fuel passing into the exhaust stream. Common causes include:
· Incorrect fuel injection timing
· Defective fuel injectors
· Low cylinder compression

Low cylinder compression may be caused by leaking valves, sticking piston rings, ring wear, cylinder wear, or cylinder glaze. When white smoke occurs at cold start and then disappears as the engine warms up, the most common causes are fouling deposits around piston rings and/or cylinder glazing.
Continuous evidence of white smoke indicates a mechanical defect, or incorrect fuel timing.

 

[lostmarbles]

Statistical proof because I'm a papered mechanic with 1000 rebuilds under my sleeve and the laboratory in the back room. Nope, not me.

The HD mechanics at work have mentioned this, and have asked we put the trucks on high idle when parked at an incident. This is for electrical load concerns as well.

From conversations with diesel mechanics, as I pick their brains.

Filtered through reading and research.

I bump the idle too when wheeling and stopped for whatever reason (when I remember), and I would not turn it off simply to get out and check something. I understand "excessive" to mean hours and hours.

TheDieselStop.Com - www.thedieselstop.com

http://www.wjwatson.com/files/runningin.pdf (diesel generator info)

Get past the marketing, there is some good information...from your neck of the woods: Colour of engine smoke and when it occurs tells about internal condition

Marine diesel engines: maintenance ... - Google Book Search

Piston glazing and your "modern" diesel - Australian Land Rover Owners

Tonnes more out there if you want to read...








And...

Scary stuff here: Diesel Talk Forums - Glazing of cylinders read the de-glazing post. Yikes!

Wow. Tons of interesting reading there Greg. - Thanks.

But most of it refers to how bad it is to idle a NEW or RECENTLY-RECONDITIONED diesel. (Prolonged idling causes the newly-honed cylinder walls to "glaze" before the rings have time to "bed in".)

I still think that any diesel is far better suited to "prolonged idling" than any petrol engine. (Ignoring "running in" periods.)

But having said that, I agree that "prolonged idling" isn't good (in general) for any engine compared to "normal running".

(And I suspect we probably really share similar views on this Greg.)

I'm not really sure why I like to pull the "handle throttle a little" to increase my idling revvs. I think it is because I suspect I get better oil circulation doing that.

Anyway ...... I just wanted to dispell any suggestion that people should turn their diesels off whenever they stop (to chat to occupants of another vehicle they meet on a lonely track, or to check a river crossing or whatever). I reckon the wear on starter-gear would more detrimental if you were to do that.


PS. You just need to look around to see how many trucks and buses (all diesel-powered) are left idling for extremely-long periods on a regular basis (with no attempt at all to increase their engine-revvs either). ------ And I'm as guilty as anyone of doing this.

 

[canucksafari]

I always tell people to smell the smoke becuase far too often they mystake the colours - odor is a whole different ball game.

As for idling, I always idle up. If your truck has one, it's there for a reason. As for shutting down, I always do that a drive throughs and especially the border.

 

[9180ltd]

ideling

i have to agree with the idel up recomendations, i know most here havent come accross a detroit 6-71 before but if you have you would agree 2 fold. when those motors idel for even 1 hour they start to slober oil out of the exhaust and blow clouds of smoke on acceleration after