The good, and the bad - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Project1970 · 06-28-2002, 05:32 AM

Good: In an odd little 4-way street race (lined up with an Integra in left lane, Dakota in front of me in middle, and some other import to the left of me) I managed to beat two of the other three cars.

The import next to me never had anything for me, and even after lagging the start to avoid rearending the Dakota, I just drove right around him...started out a carlength behind and ended up one ahead by 70mph

Bad: I got the very distinct smell of burning oil after that hard run, and one immediately prior...I'm starting to guess that most of my oil consumption happens when I wrap the engine up to 3500RPM and higher. The rest is either the drippings or the valve stem seals on startup.

I've got plenty of crankcase ventilation (in a vain attempt to reduce a front main leak) so that's not the problem. I do notice that oil seems to be coming from the breathers, so it looks to me like this thing is building up some nasty crankcase pressure.

What would cause that? Blowby?

Hey, it might get me another excuse to dump this 122,000 mile old 350 for a new crate.

*Randy70C-10* · 06-28-2002, 08:56 AM

Are you running oil breathers on both sides? You should run a PVC valve on one side and the breather on the other.

Project1970 · 06-28-2002, 02:21 PM

PCV and a breather (which doubles as oil filler, heh) on driver's side, breather only on passenger side.

CE20934 · 06-28-2002, 05:06 PM

A breather and a PCV on the same side? Sounds like the PCV would pull more fresh air from the breather on its side than crankcase vapors, yielding moderately higher crankcase pressure.

I've always run a breather on the right (oil filler as well) and a PCV on the left (all directions as one sits in the cab).

lukecp · 06-28-2002, 06:28 PM

My 350 used to smell like burning oil when i got
it up to around 4000 rpm, and i thought i was having
some blowby on my 12,000 mile engine. But, i had just
installed new valve cover gaskets, and the rear corner of
the driver's side cover gasket had been accidently smushed
to the inside of the cover, with only about 1/8" of gasket
doing the sealing. When i revved the motor, oil would squirt
out and land on my headers, making me think that it was
burning oil. It may not be your problem, but i would check it
out anyway. Ten bucks for new gaskets would be better than
over a grand for a new motor.....

Project1970 · 06-29-2002, 05:12 AM

I never thought about that issue with the PCV and a breather on the same side...hmm...

And I think I'll check those valvecovers, I do have a sneaky suspicion that those punks are leaking again. I'll use new gaskets this time.

06-28-2002, 05:32 AM	#1
Project1970 14.1 @ 96MPH Join Date: Jul 2001 Location: Mesa, AZ Posts: 2,811	The good, and the bad Good: In an odd little 4-way street race (lined up with an Integra in left lane, Dakota in front of me in middle, and some other import to the left of me) I managed to beat two of the other three cars. The import next to me never had anything for me, and even after lagging the start to avoid rearending the Dakota, I just drove right around him...started out a carlength behind and ended up one ahead by 70mph Bad: I got the very distinct smell of burning oil after that hard run, and one immediately prior...I'm starting to guess that most of my oil consumption happens when I wrap the engine up to 3500RPM and higher. The rest is either the drippings or the valve stem seals on startup. I've got plenty of crankcase ventilation (in a vain attempt to reduce a front main leak) so that's not the problem. I do notice that oil seems to be coming from the breathers, so it looks to me like this thing is building up some nasty crankcase pressure. What would cause that? Blowby? Hey, it might get me another excuse to dump this 122,000 mile old 350 for a new crate. __________________ Project1970 - LS1 Swap Complete!

06-28-2002, 02:21 PM	#3
Project1970 14.1 @ 96MPH Join Date: Jul 2001 Location: Mesa, AZ Posts: 2,811	PCV and a breather (which doubles as oil filler, heh) on driver's side, breather only on passenger side. __________________ Project1970 - LS1 Swap Complete!

06-28-2002, 05:06 PM	#4
CE20934 Senior Member Join Date: Apr 2002 Location: Help! I'm in an office park with its own network of freeways! Posts: 470	A breather and a PCV on the same side? Sounds like the PCV would pull more fresh air from the breather on its side than crankcase vapors, yielding moderately higher crankcase pressure. I've always run a breather on the right (oil filler as well) and a PCV on the left (all directions as one sits in the cab). __________________ '67 C20--427 tall deck/SM420, 4.10 HO52 (Michigan has not been kind to the Old Man) '95 Caprice--355 LT1/T56/3.42 8.5" 10-bolt (daily driver, almost 300k on the chassis) '07 Outback--wife's car. 125k & counting. No head gasket or transmission issues yet. fingers crossed

06-28-2002, 06:28 PM	#5
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	My 350 used to smell like burning oil when i got it up to around 4000 rpm, and i thought i was having some blowby on my 12,000 mile engine. But, i had just installed new valve cover gaskets, and the rear corner of the driver's side cover gasket had been accidently smushed to the inside of the cover, with only about 1/8" of gasket doing the sealing. When i revved the motor, oil would squirt out and land on my headers, making me think that it was burning oil. It may not be your problem, but i would check it out anyway. Ten bucks for new gaskets would be better than over a grand for a new motor..... __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

06-29-2002, 05:12 AM	#6
Project1970 14.1 @ 96MPH Join Date: Jul 2001 Location: Mesa, AZ Posts: 2,811	I never thought about that issue with the PCV and a breather on the same side...hmm... And I think I'll check those valvecovers, I do have a sneaky suspicion that those punks are leaking again. I'll use new gaskets this time. __________________ Project1970 - LS1 Swap Complete!

06-28-2002, 08:56 AM	#2
Randy70C-10 Account Suspended Join Date: Mar 2001 Location: Virginia Beach, Va. U.S.A. Posts: 15,320	Are you running oil breathers on both sides? You should run a PVC valve on one side and the breather on the other.



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