the flyin' scotsman

On my to do list this winter along with the intake R&R is renewing the valve cover gaskets.

Couple of questions:

- do the tbelt covers have to be removed for room?
- can the chain tensioner pads be replaced without removing the cams?

Any other WYAI's?

Schocki

The belt covers can stay on.

The complete cam chain tensioners have to be removed. The cams can stay in place. Easy, no problem.
The procedure is described in the 944 WSM. Be careful with the torque values! The oil line banjo bolts are very fragile. You can get the 944 manual here: http://www.cannell.co.uk/Manuals.htm

The driver side is very easy. The passenger side is a PITA, you have to remove the engine hoist hooks from the cylinder heads to remove the covers.

Here is my old write up: https://rennlist.com/forums/showthre...ight=tensioner

SeanR

Schocki,

I really think you should have stayed here in the DFW area. I had the chance to meet you the 1st time I met the DFW crowd and the 1st thing you said was to get rid of that damn K&N, and get some motor mounts.

Thanks for being a part of the Rennlist community, you are a wealth of knowledge.

worf928

You can leave the t-belt stuff alone. The cam covers come off and go back on with the least risk (in terms of damaged parts and/or leaks when you are done) if you:
- disconnect the air pump diverter from the exhaust and the head so that you can flop the entire assembly out of the way
- remove both lift loops
- unbolt the LH-harness guide at the back of the p-side head.

As for WYAIT,
- I recommend replacing the Hall Sensor unless you know that it's less than a few years old. (The connector is made of the same brittle stuff as the knock sensor connectors and it is very easy to damage the HS connector when you remove the p-side cam cover. Also, the HS is easy to remove with the cover off, not so much with the cover on.)
- you can also clean the oil check valve in each head. Although I've yet to find one that was gummed-up.

the flyin' scotsman

Great feedback guys.............the passenger side is a little more tricky but the air pump plumbing is long gone.

I have the Hall Sensor on my list also Dave; is it an age related replacement? is there a test that ensures reliability? or because I'm in there just change the 20 YO thing?

worf928

The only 'easy' test I know of is with a Hammer telling you if you've already got Hall Sensor faults. That's ain't gonna help you though.

I recommend replacing the HS for exactly the reasons above plus what you wrote:
- easy to do with the cover off. PITA with it on.
- 20-year old electrical part
- easy to damage the connector when you pull the cover
- connector made of the same stuff as the knock (and flywheel) sensors, which we all know turns to dust when you disconnect them

EDIT: In my experience there's a 75% chance that the HS will be bad by the time the p-side cover is back on and bolted down.

jon928se

I haven't seen a gummed up one either but every one I have seen has needed the O ring replaced that seals the plug on top of the valve into the head.

TRUESCOTSMAN

good idea to replace the rubber seals that stop the oil filling up in the spark plug holes as well. When you remove the covers and break the seal between the cover and the old seals, they never seal the same again. Years of heating up and cooling down either dry out the rubber or shrink them a bit. Saves having to go through the process twice or ending up with 8 beru dipsticks...... Ask Algie

Schocki

Sorry,

Home is where the air force or better Luftwaffe sends you

What would Germany do without me??? Just kidding!

Tails

Malcolm,
There is a test for the Hall Sensor (Hall Sender Signal) as described in the 1987 928S4 Test Plan for EZK - Ignition and LH - Jetronic, however, you will need an oscilloscope.

The description on how to perform this test is listed as Test Step 7: Hall Sender Signal on page 2 - 21 of this Service Manual ( contained in Jim Morehouse's CDs).

The method described is as follows:

Disconnect plug on cylinder head 1-4 behind camshaft drive gear and connect a 3-pin adapter lead (VW 1501) between tha plug and the cylinder head to test the hall signal.

(Of course the female socket of the plug will fall to pieces, as mentioned before, but replacement can be obtained from BOSCH or after market suppliers).

Connect positive and negative tester lead on terminals 1 and 2 of adapter lead, connect tester to instructions supplied with tester and start engine. (Note: this means that if you don't have a adapter lead (VW 1501) you will have to make an adaptor with positive and negative tails interconnecting the plug and socket and have tails joined to the jumper leads to connect the oscilloscope to).

Following signal will appear on the screen if the hall sender is ok. ( Sorry cannot copy signal as resolution too poor, however, the voltage signal is shown as a flat line over time and rises vertically to approximately 5 volts when hall sensor signal is sensed then slightly degrades as it passes the trigger and then falls vertically to zero again as the sensor is passed).

If the hall signal or one of the knock sensor signals is missing, ignition timing will be retarded by about 6 degrees for all cylinders in upper partial load and full load ranges by the control unit (protective circuit).

Tails 1990 928 S4 Auto