athenian

While doing the Timing Belt/Water Pump change on my '91 S4 Auto (for the first time), I created a problem! I moved the left side (cyls 5-8) cam sprocket out passed the 45 degree timing mark....What do I do now??

The photo below shows the WHITE marks on the cam sprocket and the back plate for TDC...The RED mark on the cam sprocket is the 45 degree mark. As you can see the RED mark (and white mark TDC) has passed the reference notch on the back cover. How did it happen?? I was trying to align the Timing Belt perfectly and I pulled a little too hard on it...and the cam gear slipped passed the reference mark...



The right side (cyls 1-4) cam pulley is aligned with the reference mark at 45 deg just fine...The flywheel is locked with the special tool and the crank is set at 45 deg.

Can I rotate the 5-8 cam pulley/sprocket clockwise once around to re-align the marks?? Will it hurt anything in the process??

Any advise will be appreciated - Thanks and Happy New Year!

Vasilis

'91 S4 Black Auto

Bill Ball

As long as the flywheel is locked at 45 degrees, no harm can be done. Rotate the cam gear to the correct position. If you overshoot, go around again. It is common for the cams to rotate off a lobe like this.

Garth S

If the crank is locked down at the 45 deg. mark, you can safely rotate either cam back to the 45 deg reference in either direction: remove the distributor cap, and turn the cam by the large nut - 17mm IIRC on the 32v.
Matter of fact, that is the better technique to get the new TB installed correctly - simply rotate a tooth or two clockwise to catch the belt such that when the cam is released the index marks match, and the belt is under slight tension.

athenian

Rotate cam clockwise to 45 degree reference mark??? BRILLIANT idea!!!!

Thanks a bunce for the quick respose and timeless advice...I thought I was the only dummy who made stupid mistakes like that....

Happy Holidays!!!

Vasilis - 91 S4 Black Auto

Garth S

Bill is likely correct - but, if the cam slipped off a lobe and rotated clockwise, I would reposition it by the 'path wence it came' - rotate counterclockwise in this case. While the 45 deg. mark is the safe haven for an interference engine, I like to minimize any cam movement: in the case you mentioned, that would be a pointless ~340 or so rotation clockwise.
The "clockwise rotation rule" applies and is important when the TB has been installed - not in repositioning a slipped cam: "the shortest distance between two points ....."

928ntslow

Of course take the rotor off first and use a large wrench or breaker bar with Socket. You are going to have to do all of this anyway to align the cams when you put the belt back on.

Bill Ball

Yes, I see no problem rotating the cam gear backwards. Just don't do that with the crank as it throws off the belt tension and timing measurement a bit. As Keith points out, of course, you can't do much until you remove the rotor.

athenian

All is well so far....The new belt is on and the cams and timing marks are aligned as specified (after rotating the left cam backwards - thanks for the suggestion)..Removed the clutch tool and rotated the engine a few times clockwise...

Now the crank is turning fine and all the timing marks are aligned again....I placed the engine at TDC and attempted to correctly tension the TB....I'm using the Kempf tool for that...The tensioner adjustment screw is set...I have rotated the engine several times trying to set the correct tension using the Kempf tool at TDC....

Below are a few photos of the Kempf tool on the belt + measurement taken...








Question on the Kempf tool...Should the smaller edge on the tool be anywhere INSIDE the small window for correct tension??

Many thanks to all for the help - Vasilis

'91 S4 Black Auto

Peter F

It should be in the middle of the window.
(the edge that is)

Cheers/Peter

WallyP

I think that most of us go for the max tension within the wndow...

Bill Ball

I go for mid. Overtensioning has its hazards too.

Make very certain the tensioner has a full charge of oil. Even then there is a tendency for the oil to leak out. The result is the bimetallic washers inside the tensioner do not respond to engine heat as well and expansion of the block raises the belt tension. In my case, new cam gears lost all the annodization in less than 25K miles and the belt stretched excessively requiring two adjustments during that time. It's unusual to require a retension other than perhaps at the 1500 mile check, although it should be checked every 15K miles. I had to replace my belt at 25K miles due to lack of oil in the tensioner.

Red UFO

Cool I'm right in the middle of doing the samething.

athenian

Great - thanks again for your input Bill, Peter & Wally.....So the general consencous is to set the tension WITHIN the small window, when using the Kempf tool....

Regarding the oil in the tensioner...I have filled mine to the max and since tensioning the belt I noticed a few drops coming out of the middle of the tensioner boot...That's the area in the middle where the small plunger comes out...I installed a new boot but used the old clamps as they looked okay...Only a few drops of oil leaked out and I will check it again in the morning to make sure....Maybe there's too much oil in the tensioner (is this possible???)

I've read several posts where some folks discovered they had bone-dry tensioners when it came time to do the replacement...It seems that the tensioner can still function okay without a full oil capacity...Is this a valid assumption or can somebody provide a better explanation???

Bill Ball - I'll be particularly interested to hear your story as to how your tensioner leaked out the oil...

All the best - Vasilis

'91 S4 Black Auto

borland

On the cam sprocket.... The hex washer behind the bolt is designed just for what you needed to do, rotate the sprocket back into position before installing the belt. There's no other reason for this washer to have a hex.

While you had the tensioner removed, that was a good time to replace the smog pump with a rebuilt one. You'll thank me later.

Bill Ball

The tensioner "leak" is odd. First off, mine never took much oil to begin with and I don't understand why. Filled according to the manual through the correct bleed hole until it came out the other. Took maybe an ounce. Weird. I think it may have been mostly trapped air. Tried pumping the tensioner. I was very careful with the sealing surfaces and gasket, but in the days after assembly I saw oil drips below the tensioner. In the subsequent months I had the warning light come on twice and the tension was at the low end of the range. After the second time I redid the belt, gears and rebuilt the tensioner again. Still didn't take much oil and seemed to lose it quickly. I squirt some in periodically. I haven't figured it out yet.