Date:         Mon, 14 Apr 2008 20:59:46 -0700
Reply-To:     Mark Drillock <drillock@EARTHLINK.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Mark Drillock <drillock@EARTHLINK.NET>
Subject:      Re: Vanagon/Jetta timing issue. Use RPM sensor hole to find #1
              TDC mark?
Comments: To: neil N <musomuso@GMAIL.COM>
In-Reply-To:  <c4e7c5f90804142032v4fce0e88lcd825f19a4b33b18@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

You have a 4 stroke engine, also called a 4 cycle. (I don't mean 4 cyl
though yours is that too)

With a 4 stroke engine it takes 2 complete revolutions of the crank to
complete a full cycle. With a 4 cylinder 4 cycle that means the crank
timing mark will line up for 2 different cylinders at TDC at the same
time. One will be lined up in its compression stroke TDC and the other
will at the same time be lined up for its exhaust stroke TDC.

The firing order of the VW inline engine is 1-3-4-2. That means that
cyls 1 AND 4 will be at TDC at the SAME time, but at different phases of
their valve timing. VW provides a cam timing indicator so the valve
timing phase can be checked against cylinder #1 TDC. Once timing for #1
is correct the others must also be so.

Mark


neil N wrote:
> Hey everyone.
>
> Haven't got my Jetta ABA 2.0 engine started yet. Timing sounds wrong
> even though I have timing marks "correct".
>
> When engine turned over, it sounds like this:
>
>  "whir whir whir" (slight pause) "whir whir whir" etc. It sounds
> labored with very distinct "whirs" if that makes sense.
>
> Starter is fine, as is battery.
>
> I need to confirm TDC of #1 cylinder, but obviously can't see the flywheel.
>
> Bentley shows a gear attached to crank, that RPM sensor "reads". There
> is a factory gap on gear. (2 teeth missing). RPM sensor reads this gap
> as TDC for #1 cylinder.
>
> With sensor removed, and gap on gear lined up with RPM sensor hole in
> block, crank pulley mark is at 9:00 and distributor points close to
> #4. This somewhat confirms my suspicions. But i"m not certain.
>
> Anyone know if I can use this gap on the gear as reference for #1 TDC?
>
> This is an interference engine AFAIK, so I don't want to screw with
> timing any more than I have! --- :^)
>
> Thanks,
>
> Neil.
>
>
>
> --
> Neil Nicholson. 1981 Air Cooled Westfalia - "Jaco"
>
> http://web.mac.com/tubaneil
> http://tubaneil.googlepages.com/
>