LB7: Smoke or blow by

FF34PIP

New member
Jun 19, 2009
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Pryor, Oklahoma
I was pulling my camper and noticed some slight smoke from under the hood when i stopped, it smelled like oil. Pulled over and could find nothing. Once I got back home and looked a little better I noticed some oil below the tube that comes out of the front passenger side of the block. I cant tell if it's doing it all the time, I've only seen and smelled it a few times since. Doesn't seem to be running any different. I have a PPE tuner set on #2 and a boost valve.
Anyone have any ideas?
 

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
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Oil on pass front of an LB7 is "normal", thats where the crankcase vents.

Many questions to answer to even make an attempt to help...

How much weight were you towing? Hills or level ground? Engine under a lot of stress? Does it only make the smell after towing or under normal drivng?
How many miles on the truck? Last time you changed oil?
Ever checked the injector's balance rates? If so, how did they look?

Only real way for anyone to diagnose it is to be there to check the vehicle out, so the more info you give helps.
 
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FF34PIP

New member
Jun 19, 2009
19
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0
Pryor, Oklahoma
I'm towing about 9500 over the hills and through the valleys. Motor under stress. This was the first time to ever smoke or smell, now it does it all the time. Got under the truck today and I could see a little smoke comming from the vent tube. I changed the oil less than a 1000 miles ago, the truck has 160,000 mi. on it. I dont know how to check the balance rates.
 

whitetrash21

put on da damn helmet day
Apr 29, 2008
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Pull your dipstick and let a drop fall on a paper towel. If it @eperates into a light ring and a dark ring theres fuel/coolant in the oil. A crankcaase full of fuel will cause the breather to huff oil or smoke.

Its an easy check. Also, anyone with a tuner or efi can check your balance rates. Dealer can as well
 

FF34PIP

New member
Jun 19, 2009
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Pryor, Oklahoma
There were a few dark spots when i first dropped it on the towel but it didn't make two distinct rings. If there were coolant, wouldn't it make the oil milky looking.
 

whitetrash21

put on da damn helmet day
Apr 29, 2008
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There were a few dark spots when i first dropped it on the towel but it didn't make two distinct rings. If there were coolant, wouldn't it make the oil milky looking.


Yep. You'd see it on the dipstick too. Fuel is hard to see, but when dropped on a towel, it seperates from the oil. Fuel in the oil is usually a sign of a bad/hung injector on an lb7.


If all you have is oil, thats a good sign. I know my lb7, when hot, would smoke a little out of the breather, but I had to be beating on it pretty hard to get that.

You're saying that just daily driving it does that now??
 

maxaholic

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Dec 6, 2008
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How hot did your egts get? Or do you even have a pyro. My guess is that you either burnt a piston or gaulded the rings. But that's just a guess.