6V92T no power black smoke

Fredward · November 17, 2009, 06:57:22 PM

So we got new member's (Number3) Eagle home from Alabama. 6V92TA ran like a champ with the exception of needing to change fuel filters after about 200 miles. Now that we've got it back here in Minnesota it just started lacking power and blowing black smoke under acceleration. Starts and idles just fine. I know we need to replace the air filter because its how old? I drove it 1100 miles without incident aside from loosing power at one point and changing fuel filters. All of a sudden; the last 10 miles it started loosing power and making black smoke under acceleration. Starts and idles fine; no black smoke; just blue.

Now this is a half worn out 6V92T that has 10w40 (yuck!) in it that slobbers at idle when cold. So I know this is no spring chicken. My questions are:

If fuel filters are plugged again would it be smoking black? I don't think so.
How can I test if the turbo is failing - thus causing the black smoke?
Maybe its just the air filter. We'll get a new one.

Our local Detroit mechanic should be available soon and we'll have him inspect it and run the rack. Just wondering what could change in just a few miles to cause this symptom?

TomC · November 17, 2009, 07:06:47 PM

Sounds like classic air filter clogging. Air filters can go fine for a long time then rather suddenly (like you just experienced) it gets to dirty to pass sufficient air. If you still don't know, just take the filter element out of the can and drive it a short distance without the filter to see if it is still smoking. Black smoke=too much fuel. Blueish smoke=oil burning. White smoke=unburned fuel. Good Luck, TomC

RickB · November 17, 2009, 07:12:37 PM

Fred,

Is it mechanical or DDEC ?

Also give her a good oil change with straight 40 asap. I have a friend and it has taken awhile for his motor to quit leaking like a sieve after running 15/40 rotella in it.

My airfilter was robbing me of horsepower but it never did what your describing. Unless you have a nest in it that became dislodged I doubt that an air filter would cause the kind of quick changes you are talking about.

Can you pull the turbo and see if it has let a seal go?

Is the engine misfiring or just lack of power?

From the engine compartment if you rev the motor can you hear the turbo spooling up?

Just some thoughts.

Rick

luvrbus · November 17, 2009, 07:14:35 PM

Fred, sounds like you have a bad exhaust leak or the connection hose blew between the turbo at the intake.
Remove the air cleaner at the turbo if it spins free without a great deal of slack up and down , in and out it's OK you can feel some play so don't worry about that.
good luck

Fredward · November 17, 2009, 07:36:07 PM

Rick,
Its a mechanical silver 6V92T. I have not had my head in the engine compartment revving the engine. Thats a good idea. We know the oil needs to be changed but its Minnesota and winter and all its going to do this winter is get moved around the shop and maybe a few miles to the cabinet maker so we'll probably wait til spring. I know straight 40 made a huge difference in my 8V71. The engine is not mis-firing. It acts like it did down in Missouri when the secondary filter plugged except now it smokes. Just doggy. (I don't think it smoked back then but it was raining so hard I might have missed it?)

What do you mean pull the turbo. Am I looking for oil leaks from the bearings? or oil leaking into the compressor side? We can easily get at it as its right on the back side above the fan drive gear box.

luvrbus,
You could be on to somethiing with the exhaust leak I had not thought of that. Also as Tom said the air filter could be our enemy here but I am afraid to drive it without because its two miles of gravel to the pavement. We'll order a new filter for it. For sure I can remove a hose and reach in there to see if it spins freely.

The bus isn't here right now; Number3 took it to a welder to fix the rust issues. Hopefully it'll be back by this weekend and we can dig into the engine issues.

Fred

edroelle · November 18, 2009, 04:34:10 AM

Fred,

This is independent of your loss of power and black smoke.

You want to change the oil now, even if you don't drive it at all over the winter. Acids and moisture have built-up over time, and you don't want them sitting or circulating in the engine.

A recent thread on the DD Bulletin Board indicated an overwhelming vote of - change oil before winter rather than in spring.

Ed Roelle
Flint, MI

Ed Hackenbruch · November 18, 2009, 08:20:01 AM

I have seen equipment start up fine in the morning and after a couple of hours of working lose power and start blowing black smoke. New air filters or even blowing them out and they are back to work. That would be the first thing i would check......even if that isn't the problem, it isn't going to hurt to have new filters in anyway.

blue_goose · November 18, 2009, 02:56:52 PM

I know from haveing it happen, if the fuel filter is need ing changed it will smoke bad and have no power. Been there done that.
Jack

Ed Hackenbruch · November 18, 2009, 05:13:21 PM

Yup, seen that too.

hargreaves · November 18, 2009, 05:27:46 PM

Check the blower shaft and make sure that the splines are not worn down and the blower is not spinning properly. Another thing that can cause smoking and poor acceleration is the blower bypass valve. If it is stuck open it will cause smoking. The way to test this is to put your hand on the valve and with the other hand very lightly tap the valve with a hammer. If you feel a clunking sound, it's a good posibility the valve was stuck. You can take it out quite easily and check for carbon build up. Good Luck

Gerry

Van · November 19, 2009, 07:08:29 AM

Fred,Any update on the smoke?thanks.

Van

Busted Knuckle · November 19, 2009, 07:21:58 AM

Quote from: van on November 19, 2009, 07:08:29 AM
Fred,Any update on the smoke?thanks.

Van

Probably not yet it's at a welding shop waiting on rust repair! (could be a while, it is an Eagle ya know!

)

Sorry the debil made me do it!

BK

Fredward · November 22, 2009, 08:28:55 PM

Yah BK's right its a few miles away being welded on.

It could well be the filter (air or fuel). Hopefully it will be back here by Thanksgiving at we can dig into it a little more.

Gerry: the blower bypass valve? You mean the mechanical blower on top of the engine - right? Where would I find the bypass valve? Is this specific to the 92 series engines? I don't recall seeing anything like that on my 871.

Fred

luvrbus · November 23, 2009, 05:50:08 AM

Fred, the by pass valve is at the rear of the blower if you have one not all turbo 2 strokes have it is about 2 inches in dia and will have a 1/4 inch hose from the valve to the end plate.
That is not you problem the function of the valve is to by pass the blower when the turbo builds up pressure lets the blower free wheel to save fuel

good luck

Bestekustoms · November 23, 2009, 06:27:09 AM

OK.....Now Im On The Right One

We Got Two Smoking/ Screwed Up 6v92 Posts Going At The Same Time.Must Have Hit The Wrong Button A Little Bit Ago

I Wanted To Say.....Great Info. I Feel Like I Learned Something Today.

GREAT STUFF !!! Thats What Its All About !!

Get That Eagle Welded Up.

Clifford, How The Hell Can You Remember All This Stuff?? Man. The Older Im Getting The Less Stuff I Can Remember. So......You Must Be DA MAN !!! 10-4

JOHN