[Vwdiesel] 1.6L Diesel Compression

[Doyt W. Echelberger]

Hello Nick..............When testing compression, all injectors are removed 
first and the compression tester is inserted one cylinder at a time. This 
makes it easy to spin over the engine, which is basically experiencing 
compression in only one cylinder. Multiple missing factors detailed below 
greatly reduce the possibility of a cylinder firing during the testing 
process.

Multiple factors negating a detonation: Squirting a small volume of liquid 
SAE 40 (fairly heavy viscosity compared to diesel fuel) into the cold 
cylinder is exponentially different than injecting a measured charge of 
atomized diesel fuel into a cylinder containing a glowplug heated to over a 
thousand degrees.

Reflecting on what we already know......the most common reason our diesels 
don't start easily or at all is that one or more glow plugs are dead or 
and/or the injectors aren't spraying a proper pattern. Two dead glow plugs 
makes starting very problematic. To prove this to yourself, try starting 
your diesel with all 4 glowplugs  cold.....even with good injectors, you 
might burn up the starter wire before you get it running.

Bottom line: Consider the above, and recall that in the compression testing 
situation, the one sealed cylinder doesn't even have an injector to atomize 
the fuel charge, much less having a hot glowplug.

Doyt


 >>>>>>>>>>>>>>
At 08:35 AM 11/24/2007, you wrote:
>One problem with putting oil in the cylinder to check for leaks, due to it
>being a diesel isn't there a concern of cylinder fireing if to much oil is
>used? Thus making it a bad day for the pressure test gage.
>
>Nick
>
>-----Original Message-----
>From: vwdiesel-bounces at vwfans.com [mailto:vwdiesel-bounces at vwfans.com] On
>Behalf Of Doyt W. Echelberger
>Sent: Saturday, November 24, 2007 1:50 AM
>To: MikeyBigFish at wmconnect.com
>Cc: vwdiesel at vwfans.com
>Subject: Re: [Vwdiesel] 1.6L Diesel Compression
>
>At 10:41 PM 11/23/2007, you wrote:
> >Folks,
> >
> >Anyone know what cylinder compression should read on fresh 1.6L diesels?
> >Also, what is the unacceptable level?
> >
> >Thanks, Mike in
> >VA|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
>||||||||||||||||||||||||||||||||||||||||||||||||||||||
>
>Hello Mike...............Robert Bentley claims to know.....quoting from
>my  Jetta/Rabbit Diesel Service Manual... 77-84:
> >Compression should be between 398 and 483 lbs per square inch (psi).
>Difference between any two cylinders should not exceed 71 psi.
>Low pressure in adjacent cylinders may be due to a leaking head gasket.
>To determine if low pressure is due to rings, squirt SAE 40 motor oil into
>the cylinder through the injector hole and repeat the test. If readings
>then are higher, the rings are faulty. If the readings are still low,
>suspect faulty valves or a leaking head gasket.
>
>Doyt in Ohio