mark kibort

usually, at 45 degrees, the passenger side will snap 4 teeth one direction. (ccw)

if it doesnt, thats weird. cam timing can effect that i imagine. if at TDC, the driver side then becomes the unstable one and the passenger side is spring loaded.

I have never heard of anyone pulling a timing belt off and having the pulleys remain at the marks... anyone else here seen this??

giddyupp

Yeh - I just did this a couple of weeks ago. Nothing moved at all - Car seems to be running fine except for a noise coming from the font of the engine that I am trying to track down. sounds like a bearing on one of the ancillaries - really hoping its not a crank bearing. Oil pressure seems to be fine.

Imo000

Disconnect all the accessory belts and if the noise goes away, you'll know where to look.

SeanR

Some cars cams will move, some won't. The only time I put the crank at 45 is when I'm removing cams/heads. Otherwise all the TB/WP changes are done at TDC.

Hobibill

This:

https://rennlist.com/forums/928-foru...his-noise.html

Seems it was bad tension arm alignment in my case.

giddyupp

Interesting - Only problem though is that I too installed the Porken Tensioner, so not sure it this can still happen. I will pull the cover and take a look at the tracking though

hwyengr

Has anyone reported damage from the cams moving with the crank at TDC? If the cams move because of spring pressure, why wouldn't they snap to a neutral, no-spring-load valves-closed position?

docmirror

I've never heard of anyone damaging anything by leaving the crank at TDC.

When the belt is removed, the cams will often spring to their position of least mechanical resistance. It will be some combo of least spring pressure on both intake, and exhaust lobes and without going into a lot of geometry, one or both might move up to say, 40 deg. There's no way for the spring pressure on the cam lobe forcing the valve back up will cause damage from another different valve striking a piston. In the absolute worst case, the spring pressure expanding will not have anywhere near enough force to bend a valve if it strikes a piston at TDC.

Once the new belt is ready to be installed, just rotate the cam back to it's tick marks line up, and thread the belt around the cam gear. No drama needed.

M. Requin

Installing new sprockets, crank at 45, no movement at all- so add me to the weird club.

Edit: I can probably stay in the weird club, but the DS cam rotated surreptitiously.

StratfordShark

That's an interesting comment about marking the belt too. Do you mark at the crank as well as the cam gears? Otherwise I don't see how you could ensure the marks line up since you start lacing belt from crank. Given that your cam gears are marked, I'm not sure I understand how marking the belt helps.

mark kibort

so this begs the qustion of why my stock head S4, has pre loading on the cams at 45 and TDC, while other here have not. oh,,,,, i have a GT cam... thats could be the diff... BUT, i just got done doing the TDC method with a stock S4 and it had the one cam snap to 4 teeth off before it came to rest. could it be cam timing. obvsoiusly, this S4, is a stroker, but that doesnt make any diff, as the heads and cams are stock S4. it is timed at about near Zero , so maybe the S4s with slightly advanced timing are more on the cusp of a cam lobe and have equalibrium and dont move.. I know my car driver side only moved a few mm at TDC, but the 4 teeth on the driver side.

anyway, sounds like you have it handled. i dont think the marking the belt does anything either, because when you string the belt, you just get the driver side on first and make the belt taut between oil pump and cam pulley. then fit the belt over the pulley that is aligned on the passenger side with the tool or a vice grip (to hold the hex nut) and you are then done.... fit the belt over by moving things around a bit and you are ready to tighen the tensioner. rotate the crank 2 revs and double check things are aligned and you are good to go.

zekgb

Mine was done at TDC and each side sprang four teeth in opposite directions - CW on the left, CCW on the right.

mark kibort

im thinking its a timing difference.. what do you have your cams timed at?

my 85 cam'ed S4, went only 1-2mm CCW on the right ,as you did, and on the left, 4 teeth on the left cam , but i think it was CCW. i cant remember now.

Mongo

I think mine only moved half a tooth on the passenger side.. probably because I breathed on it wrong.

Bill Ball and I timed the car at 45degrees using the 32v'r tool.

mark kibort

and you probably set the timing at stock specs?