Balance shaft timing?

[Greg944]

Hello all,

A while back I attended a club sprint meeting with my S2. Apart from a spin, the day went well until I drove home. I do not remember any over revving.

While driving the car experienced an engine vibration between 3500 and 4000 rpm approx. vibration not apparent on track post spin.

Car was carefully driven home, parked and not started or driven since. Some forum searching has indicated the likely causes as either the balance shaft system or the engine mounts.

The left hand engine mount has previously been identified as needing replacement (part on hand), however, I decided to inspect the engine belts.

On removing the lower belt cover, the balance shaft belt was found to be loose, ie able to twist the belt beyond 90 degrees. There is also evidence of rub marks from this belt on the water pump pulley.

Both belts look to be in good condition.

Without a timing inspection at this stage, is it likely that the balance belt make have jumped a tooth or two?

If so, is it safe to drive to a repair venue?

Cheers and thanks

Greg

[Pauly]

if your balance shaft is not timed, you'd feel a very sharp vibration, hard to miss. it feels twice as quick as the engine vibration.

 

once you take the covers off, you can see the alignment mark on the pulley. that aligns with the raised bit of plastic on the back cover. 

The bottom pulley lines up with the other mark on the rear cover. (need to be under the car to see it)

 

Make sure your engine is TCD first. 

 

You will be able to find the marking at the back on the flywheel. 

[Greg944]

Hmmmm,

Got the car on stands today to check timing.

Looking underneath, says I "that bush shouldn't be there!". One of the sway bar bushes has split in half with none remaining in place.

I start the car, warm it up.. and no engine vibration in the 3500-4000 rpm range. I now suspect the sway bar is vibrating in that range.

Off to confirm timing and change the engine mount regardless.

Cheers

Greg

[Greg944]

Found TDC, cam alignment ok, top balance shaft ok.

Cannot get lower belt cover off. Retaining bolts have seized and captive nuts are spinning. It's never easy is it? Any suggestions as to how to fix this?

Will find my inspection mirror (or buy a new one) tomorrow and see if I can confirm the lower timing.

Cheers

Greg

[Greg944]

Porsche Adeliade to the rescue with sway bar bushes, $21 each, but next day delivery.

While OS parts would have been cheaper ($7 ea) the time frame and US postage would have killed it.

Tried to confirm lower shaft timing, but access and Mossies defeated me. Saturday, fingers crossed.

Greg

[Greg944]

Hi all,

I did borrow a boroscope from a work colleague, after several checks, re confirmation that the engine was at TDC, it appears that the lower shaft is out by one (1) tooth. Clark's guide talks about re doing the timing at this point. Thoughts?

I tried to eliminate parallax as an issue, it's so close to being in(let's say 0.75 to 1 tooth out).

Would it be a case of backing the tension off, rotating the lower gear around 1 tooth and re tensioning?

Cheers

Greg

[9fan]

Stick with it Greg, you will have it sorted in the end and be enjoying the Drive !

[Greg944]

Replaced the sway bar bushes and went for a drive......

Great, no vibrations throughout the rev range.. Down to refuel, vibration has returned. What the......?

Can give some specifics; only appears at 3800-3950 and only appears sometimes....less of an engine vibration than a a vibrating sound that sounds like it's coming from the passenger side.

A quick peak underneath has found nothing loose, I do want to dive underneath properly tomorrow to check a little better. Am thinking a heat shield or so etching may be loose.

It was fun to drive though, first time since March, the M030 package is great.

Greg