Ahsai

I read it in Excellence mag or somewhere that the crankcase pressure should not exceed 9" H2O, otherwise the AOS may be faulty and creating too much vacuum. Mine measured ~6" H2O.

I used a clear tube partially filled with engine oil instead of water in case it gets sucked into the engine. Then I adjusted for specific density. Now that I have a baseline for future reference

***Update: Normal value should be 4-6" water. See the article here

Black_on_black

Oil has lower density than water, hence it makes sense that the column will be higher. You can search online for density difference - the height column will be proportional. I bet it's 0.8x lighter, hence 6" oil equals roughly 5" water...

Ahsai

Yes, that's exactly what I did - "...Then I adjusted for specific density..."
I measured ~7" oil pressure.

Byprodriver

I had Tony Callas of Callas Rennsport, who may have written the article you read, measure mine with a manometer he uses on BMWs. My rebuilt engine had 5 inches at idle, which Tony said is ideal.

Ahsai

That's it! I knew I read it somewhere...just escaped my mine who wrote that article. Thanks for the 5-inch data so now I know I'm not too far from it at ~6" H2O.

Byprodriver

Tony writes a column for Panarama & Excellence.

kromdom

good info, thanks for sharing. This method was what I had in mind for later:LINKY>>>> http://www.renntech.org/forums/tutor...for-a-bad-aos/

Black_on_black

I must have read too quickly then, my bad. Carry on...

Ahsai

Yea, saw that before but decided it's too much work and functionally no difference anyway. Not sure what's the pink stuff they put in the tube but I would hesitate to use anything other than engine oil. The reason is if the suction is too much (you have no way to tell ahead of time before you measure it), the engine will suck in whatever solution you put in the tube...Engine oil works great. Just need to multiply whatever you measured by the the specific density of the oil (0.845 for Motul x-cess 5w-40 in my case) to get the reading in water, as explained by black_on_black.

I figured. It's good to explain to other people anyway

labdag

Is there an update whether the problem was fixed?

dougn

I've only got 4 inches and I'm NOT happy about it!