ROG100

OK I have never been slow to Post my Mistakes and this one is no exception.

Finished the second tear down this weekend of the TB/WP & tensioner. The 89 went smoothly, however I became complacent on the 87. I was to quick to take of the TB and run around doing the TB dance that I forgot to mark the cam gears at the notch on both sides. The crank is locked at 45 BTDC and I am sure the cam gears will have moved if only a little bit (they always seem to do).

Now after you have had a good laugh at my stupiity I need to reset the cam gears.

I did a search and came up with the following : -
"Camshaft Alignment:
Cam alignment note: If the belt slipped, you should start with the crankshaft at 45btdc (45 degrees Before Top Dead Center) rather than tdc to keep pistons from hitting valves. Rotors point left and down. Align cam gears with notch on back timing belt cover at 22.5 degrees (3 TEETH) before the tdc notch on the cam gear to correspond to the 45 btdc crankshaft setting. There are 48 teeth on the cam gear, and 24 teeth on the crank gear. Therefore, 2 to 1, and 45 to 22.5 ratio. 22.5/360 = .0625 = 3/48. Therefore, 3 Teeth. Adjust the math if the number of teeth on your cam gear and/or crank gear are different."

This seemed to make sence and I went back to the car but found that my marks on the cam gears are three teeth plus 24 teeth. My marks are roughly at 5 o clock and the TDC mark on the TB cover is at 12 o clock. I was expecting them to be at roughly 11 o clock. Hope this makes some sence.

I checked the 89 which has the correct marks at 45 and they are in line with the TDC mark and the cam gear notch is at 5 o clock the same as on the 87.

Where am I going wrong with the 22 BTDC or 3 teeth.

Help always appreciated.

928Myles

Hi,
have the covers off my '90 S4 at the moment. If you count 21 grooves anti-clockwise from the TDC mark (count this groove as zero) on the left (petrol filler side) cam pulley you get the cam pulley to the same position as when the crank is at 45° BTDC. Other side is the same. YMMV. Hope this helps.

ROG100

928Myles,
Thats where mine are after checking mine are 21 teeth or there abouts. Thanks.

However where did I go wrong with the original explanation of 3 teeth before TDC?
This came from a thread regarding a similar subject and confirmed by some of our knowledgeable people on the board.
Thanks,
Roger

ROG100

Anyone? Bump

UKKid35

http://928oc.org/journal/T-belt1.pdf

Can't beat Wally's write up, the picture on Page 2 is what you need.

ROG100

Paul,
Thats my problem the marks do not line up as Wally said. They are roughly 180 degrees to that.
Both cars are the same and as per the post above the one in NZ as well.
My 89 is correct and the Marks are 180 degrees to Wally's picture.
Why are my cars different?
Thanks,
Roger

Garth S

3+21=24 .... sounds right to me ...

If all else fails, pull the plugs & flywheel lock ..... and gently advance the crank to TDC: confirm by #1 piston, but it can't be wrong.( Relock the crank) *.
Then, gently advance the cams the three teeth ( or so assuming there was slippage) to the index marks - and string on the TB: If any contact is felt, the crank may have to be 'wiggled' ( crank lock out)* to permit passage.

ROG100

Garth,
In Wally's picture the marks are 3 teeth from the TDC mark on the cover.
Mine are 24 WHY? Is this OK?
What am I missing?
Roger

UKKid35

As long as the crank is locked at 45 BTDC you can do anything you like with the cams (assuming you don't remove the sprocket from the cams - otherwise you will need to bolt them to the three pronged hub using 3 small bolts, to avoid having to reset the cam timing). Spin them until they do line up then refit the belt, that is the safest thing to do.

ROG100

Paul,
The crank is at 45 and the cam gears are not marked for 45. Spinning them will not help me as I have no mark to line them up. I thought I had the answer when I found that you set the cam gear at 3 teeth before TDC. Mine are 180 degrees out from that.
I am trying to understand why before I do anything?
Roger

killav

Roger,

I think you were 180 degrees out (you were on the exhaust stroke of cylinder #1) when you removed the belt. Leave the crank at 45 degrees, and rotate each cam around to three teeth before TDC. Re-install the belt and rotate crank to zero. If all marks line up, you are good to go. No need to try and re-install the belt with the camshafts 180 degrees out. I hope this makes sense.

UKKid35

Mike is probably right, but the safest thing to do is re-install the belt. There are TDC notches on the cam sprockets, they are on the inside surface. There is also a flat on the opposite side.

ROG100

Mike & Paul,
If that were the case why is the 89 180 degrees out?
The 89 was taken to TDC and the timing marks checked. Then rotated to 45 BTDC and the cams marked before removal of the belt. The marks on the 89 cam gear are 24 teeth as per the 87 and also the one in NZ.
I know the can gears on the 87 are maybe one or two teeth out as they only move slightly when the belt is removed. They never spin 180 in my experience.
So rotating them 180 would mess things up IMHO.

SeanR

Gimme a ring if you need some assistance today, I'm just bumming around the house.

ROG100

Sean,
Thanks but I will not be working on the cars today.
Best,
Roger