Vacuum Gauge -- What can it tell you?
#1
93 Touring
Thread Starter
Vacuum Gauge -- What can it tell you?
I've read a number of posts where a change in vacuum readings signaled problems.
Just wondering, what kinds of information can a vacuum gauge give you.
Also, is it just low or lowering vacuum that is a concern, or does a high or rising vacuum reading signal anything?
thanks
Just wondering, what kinds of information can a vacuum gauge give you.
Also, is it just low or lowering vacuum that is a concern, or does a high or rising vacuum reading signal anything?
thanks
#4
2/4 wheel cornering fiend
It basically depends on how well you know your engine, and even then it's not an accurate indicator of the general health of your engine.
Vacuum readings fluctuate drastically with very small changes in rpm, meaning that changes in idle speed can be deceiving. A span of 300 rpm can take you from "my engine's healthy" to "OMG, my engine's popped".
A compression test is the only sure way to determine the health of your engine.
Vacuum readings fluctuate drastically with very small changes in rpm, meaning that changes in idle speed can be deceiving. A span of 300 rpm can take you from "my engine's healthy" to "OMG, my engine's popped".
A compression test is the only sure way to determine the health of your engine.
#6
Original Gangster/Rotary!
iTrader: (213)
One thing to watch out for is a rhythmically 'ticking' needle in vacuum at a steady rpm. Usually signals a chipped or cracked seal, esp if the exhaust note sounds irregular.
#7
2/4 wheel cornering fiend
...as long as you're familiar with exactly what rpm and idle settings your idle vacuum was measured at, and you're sure those haven't changed or that you haven't developed any intake leaks whatsoever. It takes very little change in rpm to change the vacuum reading at idle.
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