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Author Topic: Why does my 6V92T smoke on startup?  (Read 1167 times)
oldmansax
Tom & Phyllis
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« on: October 24, 2011, 02:19:51 PM »

I'm getting ready to straighten out the kinks on the engine in the Wanderlodge. Best I can tell, it's been well maintained. I have a lot of the records from the POs showing regular oil changes, lube, yada,yada,yada.

It's a 6V92T, 122,xxx miles. It started out as a "red" (300 HP, maybe?) but the PO didn't like it & had it (he said) turned up to a "silver" (340 HP?). He also turned the RPMs to 2200. I can't find any paperwork on who did it or what they did.

It starts & runs fine. Plenty of power. Burns & leaks a little oil but nothing serious compared to the old DDs I had in trucks.

It smokes terrible bad on start up.... blue to blueish black color. Clears up as soon as it warms up. If I shut it down for over 2 hours it smokes. The exhaust smells like fuel pretty bad upon start up. Not so bad after I run it a while.

Other symptoms which may are may not be related: the Jakes are pitiful. I've never had Jakes on a DD but I have on Cummins & Cats. I seem to remember people saying Jakes on  a DD are not as good but these are almost not worth using. They are coming on & working from 1/2 to full stage. I can hear 'em but I can't feel 'em...  Sad

Temp is running too cool except in very hot weather. Runs around 140F. I think that it's a bad thermostat or seal.

I haven't taken anything apart yet, but I'm thinking bad seal in the turbo or blower.

Any other ideas?

TOM
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mcidave
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« Reply #1 on: October 24, 2011, 02:41:14 PM »

My 6v92 does the same exact thing as yours.  My mechanic said it is faily normal, just run it and don't worry!
Sure he said it could use a rebuild, but the cost is just not worth it right now...
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luvrbus
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« Reply #2 on: October 24, 2011, 03:22:23 PM »

Leaking injectors Tom and the Jake probably has bad cross tube seals not getting enough oil pressure to work but IMO 2 stage Jakes on 2 stroke are a waste of wire but they will never be as good as the Jakes on a 4 stroke don't except that not going to happen lol  

Those red 1800 rpm 6v92 fuel squeezer engines weren't much

good luck
« Last Edit: October 24, 2011, 03:29:51 PM by luvrbus » Logged

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oldmansax
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« Reply #3 on: October 24, 2011, 03:43:35 PM »

My 6v92 does the same exact thing as yours.  My mechanic said it is faily normal, just run it and don't worry!
Sure he said it could use a rebuild, but the cost is just not worth it right now...

I expect it to smoke a little but not this much. My 8V71 doesn't smoke at all.

Leaking injectors Tom and the Jake probably has bad cross tube seals not getting enough oil pressure to work but IMO 2 stage Jakes on 2 stroke are a waste of wire but they will never be as good as the Jakes on a 4 stroke don't except that not going to happen lol 

Those red 1800 rpm 6v92 fuel squeezer engines weren't much

good luck

Clifford,

I was wondering about the injectors.....  I have no idea who did what to "upgrade" this engine. Besides injectors & RPM change, what else should have been done?

On the Jakes, I have no experience so I didn't know what to expect. But I did expect SOMETHING!!!  LOL!! I guess I can do the cross tube seals & injectors myself but I ain't looking forward to it. Never done jakes on a DD. It's gonna be a pain in the butt to get up in there. I need to find out why the hydraulic fan stays on all the time too so I guess I'll do it all at once. If the bank robbery I'm planning goes well, I may take it over to Choo Choo Garage folks & have them do it.

Of course, if it DOESN'T go well, I won't need the bus anyway!!  Grin Grin

TOM
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TomC
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« Reply #4 on: October 24, 2011, 03:55:01 PM »

Blue to blueish black is initial oil burning.  Could be many things-worn rings, worn valve guides, etc. If it doesn't burn more then a gallon of oil every 800 miles, I wouldn't worry too much about it.
The Jakes should work better then you describe.  On my 8V-71, with my car in tow I weigh about 34,750lbs and coming down the 6% north bound grade of the Grape Vine I have to switch between 1 and 2 heads.  Very effective.  Sounds to me like you should have a precision tune up with Jake brake adjust done.  Many times a well timed and tuned engine will not smoke as much on start up.  Good Luck, TomC
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« Reply #5 on: October 24, 2011, 04:07:24 PM »

I don't have any mechanical knowledge.  I have the 6V92TA

If I start it cold, the white smoke pours out.  I worry the neighbors are going to get angry - except I doubt they can find me through the fog.  Good for keeping the mosquitoes away for awhile.
But, if I plug in the engine pre-heater for an hour it doesn't smoke at all.

I've gotten into the habit of plugging in the heater even in warm weather if I think of it.... just feels better.

Dave

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« Reply #6 on: October 24, 2011, 04:55:34 PM »

Straight weight oil for 2 stroke correct?
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oldmansax
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« Reply #7 on: October 24, 2011, 05:40:28 PM »

Straight weight oil for 2 stroke correct?

Yep, using 40wt.
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hargreaves
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« Reply #8 on: October 24, 2011, 06:42:52 PM »

Whats the temp. outside when starting it up?
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now as of Feb 2012 series 50 B400  . Sunshine Coast British Columbia
oldmansax
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« Reply #9 on: October 24, 2011, 07:24:45 PM »

Coldest has been 40F here in Maryland. Doesn't make any difference though. I started it in Mobile @75F & it smoked like a freight train. It warmed up quicker & stopped smoking sooner though.

TOM
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'82 BlueBird WanderLodge PT40 being rebuilt
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Boomer
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« Reply #10 on: October 24, 2011, 07:25:17 PM »

I would wager that it's an injector dribbling.  On start up it will run rough and smoke pretty good for a few seconds until the leaked fuel in that hole is burned off.
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hargreaves
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« Reply #11 on: October 24, 2011, 08:13:54 PM »

you might want to check the air box drains and make sure they are not plugged, or the check valves in them are not stuck.
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now as of Feb 2012 series 50 B400  . Sunshine Coast British Columbia
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« Reply #12 on: October 25, 2011, 03:42:35 AM »

Feel the exhaust manifold when starting cold. Do all cylinders warm up at the same rate. If not, the cooler one probably has low compression, usually a burned valve.
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