Re: Two problems

[Phil@sievers.demon.co.uk (Phil Payne)]

In message <013.02029525.TACE96A@prodigy.com> NED BENNETT writes:
> 
> As blowby is produced & collected in the crankcase it builds up pressure
> inside the engine, especially on the highway, because the baffle won't flow
> it out fast enough.
> 
> Now for the life of me I can't figure out why the increase in crankcase
> pressure doesn't help the light stay out instead of just the opposite...but
> this is definitely what happens. New valve cover = light out.

Maybe the excess crankcase pressure inhibits the return of oil to the crankcase 
from the top end of the engine, especially the camshaft area?  I think our old 
friend gravity is in sole charge of this process.  This would show as a 
presure drop on a mechanical gauge, which I have now decided to fit.  Gunged-up 
oilways wouldn't help - can they be cleaned out without taking the head off 
-e.g., with the camshaft cover off and some overgrown pipe-cleaners?
 
The corollary of blow-by is oil leakage in the opposite direction - but the 
engine doesn't smoke at all and oil usage is zero.

> At the speed you mentioned with a turbo engine there's going to be a fair
> amount of blowby, and you may just be pushing the limits of the design.  Or
> you might want to check the path of the crankcase gasses & see if all is
> clean & well.

Doesn't account for why I only see it once every 500 miles, and not 
continuously at high revs.  It really does just flash once, and that's it.

> What are you using for oil??  We get a lot of unnecessary lifter noise &
> oil light complaints from customers that have simply overfilled their
> crankcase by a quart or used 10-30 weight oil (even synthetic).
> Especially as the engines age, we seem to have the best results with 15-40
> or 10-50,  synthetic or otherwise.

10W50 non-synthetic, most of the time.  Not a place to try and save money.  
It's pretty standard here because of our variable climate.  I get fierce lifter 
rattle on a cold start after the car has stood for a day or two, but it goes 
completely within 3-5 seconds. Doesn't happen if I restart the engine after 
less than 24 hours.

Phil Payne
Sievers Consulting UK
Vice Chair, UK Computer Measurement Group
+44 385 302803 Fido 2:2503/415  CIS 100012,1660