Same pressure gauge for compressoon test AND manifold vacuum test?

[Jazz_89]

Hello all together :)

a few months ago I started servicing my E34 535i. The next thing on the list is measuring compressoon on each cylinder and also measuring the manifold pressure. Can I use the same tool for both procedures? I have noticed that there are special gauges with marked/coloured scale back plates. Do you have a good recomendation on what pressure gauge to buy?

Thank you

[whiskychaser]

Well, the manifold isn't under pressure as such, it is under vacuum. Vacuum specs are often quoted in inches of mercury but you could convert a negative psi reading to inHG. I have three separate gauges - compression, vacuum and fuel pressure. Plus a couple on the leak down tester. Accuracy and clear display are what counts for me. I couldn't have somebody else picking tools for me :-)

[Jazz_89]

Alright, and which vacuum line should I use? There is i) fuel pressure regulator, ii) idle air valve and iii) crankcase ventilation. Please excuse me if I am wrong

[genphreak]

Just use a tee to tap into the FPR feeder line.

Probably a good idea to install a little gauge so you can see how it behaves when driving/all situations too.

Check Shogun's contribution (Today, 03:57 PM) to KJ's thread (http://www.bimmernut.com/forum/showthread.php/40658-Well-the-poor-old-535-and-her) for an idea of how to test and observe the results.

[Jazz_89]

Got it, thanks alot