If you guys have followed many of my posts over the last year or two, you probably remember that I have been constantly whining about oil leaks. (maybe not constantly, but a lot LOL). I noticed that the more radical my engine has become, the more oil leaks seem to spring up from time to time. So here's my theory - was wondering what you think.

My first cam was a small dual pattern that made somewhere around 13" of vac at idle. Never had any oil leak probs.

Second cam was medium sized and pulled around 10" in gear. No real problems, just a couple small leaks. Normal stuff.

Current cam is bigger yet (funny how that more power bug bites, huh) and I currently run roughly 7" vacuum at idle in gear, sometimes slightly less. I've had several oil leaks with this setup. rear main seals, oil pump, intake end gaskets, front seal - PITA.

OK now I'm wondering if my crankcase ventilation system sucks. I read a bunch of old posts and the best I can figure is that a normal PCV and single breather setup needs about 6" of vacuum to operate. If this is the case my PCV may not be opening at idle speeds at all - and I do ocassionally get a little oil on the valve cover from the breather, typically after long trips or multi-round races. Cranking compression is 214 all the way around - with little variation, never done a leakdown test.

I was talking to some local guys yesterday and they unanimously suggested that I get an electric smog pump from about a 94 Z28 Camaro 350 engine and hook it up with a puke tank in place of the PCV and breather. Supposedly I can regulate it to about 12" vacuum with a spring loaded check valve and not only keep crankcase pressure negative (reduce oil leaks) but also pick up a couple HP.

What do you think?

If you can regulate the amount of vacume it pulls sounds like a good idea.

If it's relatively affordable I would say do it. Cetainly everyone would be interested in the 'experiment'. I assume there is no/minimal blowby into the crankcase. I say this because my car reads 240 # consistently and I have good vacuum but get a little seepage at high(er) sustained rpms and have a pcv system. I too haven't yet done a leakdown test but feel I have some ring wear.

[ 07-13-2003, 02:59 AM: Message edited by: RickD ]

Eric, don't be suprised if you pick up 1mph or so with the pump. I've had several customers of mine use them with good success. I think they are only around $90 or so at the GM dealer.

Here's a link to an article about these pumps and what other cars used them:

http://www.hardtail.com/techtips/vacuum-pumps.html

Thanks guys, I'll probably give it a shot. I checked the price for one at NAPA though and they wanted $163 :eek: I think they are kind of proud of their parts :rolleyes:

I may try a junkyard - I think I found a PN for a rebuild kit for the 12554580 pump - just for reference the "service kit" is 12558522.

Is there any way to measure crankcase pressure? If so, you could at least have something to compare to in order to prove or disprove the theory.

Rod

Junkyards do not have these pumps - at least around here. I did finally find GM #24505066 at www.gmpartsdirect.com (http://www.gmpartsdirect.com) for $100.55 plus shipping. The dealer wants $204.

Will update on how it works out . . .

measure crankcase pressure with a manometer. Rig up a homemade u-tube manometer filled with water and mark it off in inches. Connect it to the dipstick tube and you can measure vacuum in inches of water.