<VV> Re: 1 qt per 40 miles

[djtcz at comcast.net]

snipped, and bottom posted


From: Rodney Sampson <rsampson at kc.rr.com>
Subject: <VV> LM Engine Questions
To: virtualvairs at corvair.org
Message-ID: <43B72DD7.1050309 at kc.rr.com>
Content-Type: text/plain; charset=us-ascii; format=flowed

All:

   A few engine questions  (65 140Hp)

1)  Did a cylinder pressure study...
      1-150 3-175 5-180 2-150 4-160 6-150
      At what point should I consider rings ?

2) At present, I consume 1 qt of 20w50 oil per 40 mi run to and from work...
     excessive blowby and plugs 3 and 5 get fouled atleast once a week.
     With the above readings , I am assuming bad guides, anyother 
possibilities ?

3)  Lifters, I'm considering replacing them all but the blurb from 
Clarks advises against replacement on an old cam. I've got a couple that are very sensitive to oil levels/pressure...Comments ?

Thanks
Rodney

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History ? new problem / new car ?

If you are burning 1 qt per 40 miles I'd expect a bit of visible exhaust smoke. The unreliable rule of thumb is smoke under acceleration = rings and smoke when backing off = guides/seals. A slightly better guide test can be made with the vacuum side of a fuel pressure gage.  Here's a link with the diagnostic rules http://www.bmwe34.net/E34main/Trouble/Engine_diagnose.htm

Here is a link to the best test for guide condition.
http://www.mste.uiuc.edu/courses/ci300tcd_fall/students/Krudl_J/10_29_3.JPG

The higher compression in cylinders 3 and 5 kind of suggest they may have HEAVY chamber deposits, and if the deposits on the fouled plugs are oil, that may be how, but not why.  When I vaguely remember that  my very used 1966 Corsa had a few intake valves with back side deposits so thick they pretty much closed off the port. It also had a blown head gasket

How nasty do things look under both the valve covers?  If it's black and crusty it suggests inadequate maintenance for many miles (somewhat confirmed by cranky lifter behaviour) and it may be time for cylinder head overhaul, at least.

Dan Timberlake