blowby
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Re: blowby (madvette74)
Every engine I have ever seen has a LOT of blowby demonstrated by the smoke from the valve covers, assuming the PCV is disconnected, the breathers off, and the engine idling...it's AMAZING the amount of smoke/fumes/exhaust coming out of there....to me it seems as if every damn one of those engines throug the years, including some new dead stock one's would have some sort of defect or something,,.....it's situation NORMAL....
guess that partly explains why our engines run at somethine like 50% thermal efficiency....being optimistic...
GENE
guess that partly explains why our engines run at somethine like 50% thermal efficiency....being optimistic...
GENE
Le Mans Master
Joined: May 2003
Posts: 5,642
Likes: 1
Re: blowby (madvette74)
don't feel bad, the new avalanche engines burn up to 1/2 a qt every 1k miles until they have about 20k miles on them. weird.... my service buddy says that's just a testiment to longivety that it takes 20k miles to break in.
Tech Contributor
Joined: Aug 1999
Posts: 14,374
Likes: 6,372
From: At my Bar drinking and wrenching in Lafayette Colorado
Re: blowby (madvette74)
mad -
At 1300 miles, the rings should be seated and you should not have any excess blowby. If you're blowing oil out the breather with the PCV hooked up and working, you have a ring seating problem. With the PCV disconnected, you should have a very slight amount of blowby, but still not much. With the PCV hooked up, you should be able to hold you hand over the opposite valve cover breather hole and feel a slight suction on the crankcase.
To check it out correctly, you need to do a cylinder leakdown test on each cylinder. A new engine prior to ring seating fully will have a leakdown of about 15%. After ring seating, you should be under 10%. A well-built engine with file-fit rings will often see as low as 5%. If you're over 15%, you have a problem...
At 1300 miles, the rings should be seated and you should not have any excess blowby. If you're blowing oil out the breather with the PCV hooked up and working, you have a ring seating problem. With the PCV disconnected, you should have a very slight amount of blowby, but still not much. With the PCV hooked up, you should be able to hold you hand over the opposite valve cover breather hole and feel a slight suction on the crankcase.
To check it out correctly, you need to do a cylinder leakdown test on each cylinder. A new engine prior to ring seating fully will have a leakdown of about 15%. After ring seating, you should be under 10%. A well-built engine with file-fit rings will often see as low as 5%. If you're over 15%, you have a problem...
