Pressure testing the intake system .......Chapter 3

Chuck Pierce cpcycle at
Wed Aug 4 22:10:54 EDT 2004

Thanks for the info Derek.

Derek Pulvino wrote:

> Chuck,
> Look for some posts I sent in a couple of months ago on the topic.  I 
> don't remember what the "subject" said, probably something about oil 
> leak, but that's where all the discussion I'm aware of wrt to oil 
> leaks, leak down, and compression testing should tie back to.  It 
> shouldn't be too hard to find though, as I haven't posted much 
> lately.  So if you do a search for my email/name, you should find it 
> within about 20-back.
> In a nutshell, the data I picked up seemed to point towards high leak 
> down in the block which is causing increased crankcase pressure and 
> thus forcing more air/oil out the breather hose to the intake.  The 
> worst offender was cylinder-three.  Though I was informed the numbers 
> I got are in the "rebuild" range, the car still runs fairly well.  I 
> thought about trying to compare the % leak-down to the "good" range 
> given for our cars in the Bentley under "compression testing," but 
> nobody really knew if that would work.  IE range in the Bentley for 
> good from say 190-130 psi would equate to a "good" leak down to 68% 
> (ie 130/190=0.68).  Ah hell, it works for me, and I pay the bills so...
> Some people I've talked to have talked about the turbos leaking, but 
> not a lot of data there either.  The other thing I thought of with the 
> leak down test...not sure leaking valve stems and guides would show up 
> in the test UNLESS those leaks/loss of tightness also result in the 
> valves not seating correctly.  Also, I noted that your consumption is 
> fairly close to what I've observed in the past.
> In other news (on the consumption) I haven't checked again recently, 
> but for some reason ever since I did a t-belt and made sure ALL of the 
> intake plumbing was snug, my car runs smoother, and it seems like the 
> consumption has gone down.  First makes sense, second...not so much, 
> but I'll confirm over time.  At any rate, I've not been a quart down 
> since I did the belt and changed the oil...?
> hth,
> Derek P

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