Blowby?

VW Skibum · Post by **VW Skibum** » Tue Nov 11, 2003 8:51 pm

I have a friend with an engine problem. (I have my own aircooled problems, but we'll get to those at a later date.)

His engine (Type IV) is blowing oil out the dipstick hole pretty furiously. We checked the breathers form the valve coversto the intake air, and they are clear. We have reason to believe that the po was trying for a motor a bit hotter than stock, but we don't quite know what he did.

Next, we ran a compression check, and came up with 125-130psi on cylinders 1-3, but #4 was around 100psi. I know 125 is a bit high, but 100 should be fine. When I squirted oil down the spark plug hole, compression jumped up to 125.

My question is, is the difference in compression causing enough blowby to raise crankcase pressure? Do we need to replace the rings?

Thanks for the great info.

Max Welton · Post by **Max Welton** » Tue Nov 11, 2003 9:46 pm

It wouldn't be the difference in compression. That will just make it run a little uneven. For example, #4 could be weak because of a leaky valve. Doesn't sound like it, though.

It does sound like the #4 rings aren't sealing well. That will cause extra pressure in the cerankcase. A leakdown test will give better information.

rlarkin · Post by **rlarkin** » Tue Nov 11, 2003 9:49 pm

Sounds to me like it has too much oil in it.
If the breathers are free and clear, they should relieve enough BP that things would be ok.

turboblue · Post by **turboblue** » Wed Nov 12, 2003 9:15 am

rlarkin

Not to hijack this thread, but how did the "downpipe" installation go?
Saw your thread on the TDS and thought it was you. Good I hope.
Diesels and ACVWs, nothing like it.

rlarkin · Post by **rlarkin** » Wed Nov 12, 2003 9:53 am

turboblue wrote: but how did the "downpipe" installation go?

Believe it or not, I am sitting here at the keyboard, it is 9:30, I just finished my last prep. I have to report at 12:00. The show starts at 2:00.

Tickets go on sale at 11:00 and the doors open at 1:00.

YOO COMMIN?

turboblue · Post by **turboblue** » Wed Nov 12, 2003 12:21 pm

No thank you, but I hope your surgery goes well.
Good luck.......

cnavarro · Post by **cnavarro** » Wed Nov 12, 2003 6:37 pm

I am having the same problem with my engine. Heard the same thing from two different shops. With larger bore sizes, you get some real backpressure in the case. One shop recommended that I replace with pcv with something that doesn't only actuate in one direction. Another shop recommended using a mainlycustombydesign dipstick- I ordered one off ebay to give it a try. BTW, I thought the dipstick was the primary source of the leak and it was actually coming from between the oil filler neck and the metal breather box that goes on the breather tower. A little gasket maker about the base dryed up 95% of the oil leak.

Charles Navarro
LN Engineering
http://www.LNengineering.com
Aircooled Precision Performance

goliath · Post by **goliath** » Fri Nov 14, 2003 4:13 am

Make certain you have a genuine dipstick and its reading correctly. Fill up your motor with 2.5 litres of oil. Then check the level and run it on the lowest level marking. It all but cured my problem.

Cheers David

(2332cc 5.7 rods engle 140 9:1 total seal rings/vented rockers)

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Blowby?

Blowby?

Blow By from the dipstick