Why does my 6V92T smoke on startup?

oldmansax · 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

mcidave · 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...

luvrbus · 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

oldmansax · October 24, 2011, 03:43:35 PM

Quote from: mcidave 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...

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

Quote from: luvrbus 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

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!!

TOM

TomC · 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

Tikvah · 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

robertglines1 · October 24, 2011, 04:55:34 PM

Straight weight oil for 2 stroke correct?

oldmansax · October 24, 2011, 05:40:28 PM

Quote from: robertglines1 on October 24, 2011, 04:55:34 PM
Straight weight oil for 2 stroke correct?

Yep, using 40wt.

hargreaves · October 24, 2011, 06:42:52 PM

Whats the temp. outside when starting it up?

oldmansax · 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

Boomer · 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.

hargreaves · 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.

JWallin · 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.