timing belt tricks?

[92EcoDiesel Jetta]

I had to replace the passenger side engine mount in my 81 caddy (MK I) which required removing the timing belt and injection pump (thank you VW  ). After putting everything back together I can't get the engine to stay running.

I know the cam to crank timing is perfect and the problem is the belt being a tooth a more off on the IP sprocket. What's the trick to get the belt on the IP sprocket? I had the pin in the IP sprocket (w crank at TDC and cam lock bar in)while the belt was being installed but there was a lot of springyness in the IP which I think was throwing the belt off in relation to the IP sprocket. After I took the IP pin out and turned the engine over a few revs to TDC w cam lock bar in, the IP sprocket pin no long lines up. What are some of the tricks you use to put the belt on correctly the first time?

[bajacalal]

I always re-time the injection pump, or at least check the timing, whenever the belt comes off. We're talking about small fractions of millimeters here, it doesn't take much to throw it off just a little, even if you use a lock pin.

The official trick is to loosen the cam sprocket so that you can turn it a few degrees to line the teeth up enough to get the belt on without moving the injection pump. I think it's actually easier to just leave the cam sprocket alone, and turn the injection pump pulley a half-tooth or so, and then re-time, since you're going to be doing that anyway.

Another difficult spot is getting the crank to stay put when you tension the belt. You want the slack at the tensioner but it still tends to move a little. I've found the easiest way to cope with this, is to leave the crank not at TDC, but slightly before (I think), so that when you tension the belt, the crank lands at exactly TDC and everything is perfect. It takes a few tries to get the hang of it.

[92EcoDiesel Jetta]

Since I was quite sure the belt was a tooth or more off on the IP, it
 would have been a waste of time to time it with the dial indicator.

I marked the belt and sprockets (cam and IP) with nail polish, not loosening the cam sprocket, was able to get slack at the IP sprocket by sliding the tensioner out a little and turning the engine CCW so I can get the belt off the  IP sprocket, turn it so I can pin it and slip the belt back on. After putting everything back together and bleeding it, it started right up. Cheçked timing with dial indicator and it's at 0.039" a bit advanced for this engine. I'm leaving it as is and see how it runs and what kind of fuel economy I get.

per the marks on the belt I was one tooth off on the IP sprocket, which was enough to make it not run.

New motor mount (OE VW $45 ouch!) = no more clunk.

[gldgti]

set yourself up with a couple of homemade tools for loosening the cam sprocket and you can do it the official way every time.... after years of struggling I have found it to be the best way (for me).

[ORCoaster]

I agree that having the cam nut loose and being able to turn that pulley and have it set up correctly is the way to do the work. 

[92EcoDiesel Jetta]

I have a cam sprocket puller (a punch and hammer) and an IP sprocket puller and timed it the official Bently method. After I was done, the belt was one tooth off on the IP sprocket which made it not run. I was able to get the belt off just the IP sprocket and move it one tooth without disturbing anything else. That saved a lot of time and extra work. Checked it afterwards everything is timed perfectly and runs great.

[8v-of-fury]

naw naw naw you guys is doing it all wrong eh? You must do the easy way, and get all of the slack to the tensioner and cam shaft pulley area.

Here is my step-by-step for putting a belt on, perfectly, every time.

• 1. Get the crankshaft to TDC (like it should ALWAYS BE FIRST when you remove a belt)
• 2. Remove the cam pulley all together. Lock the cam shaft at TDC (which also should still be at TDC from when you removed the belt )
• 3. Lock the pump at its TDC. Keep the pumps pulley on.
• 4. Put the belt on and get it snugged and seated properly on the crankshaft pulley.
• 5. While keeping tension on the side that goes up towards the tensioner, so we do not skip on the crank pulley, start the belt up around the intermediate pulley to the injection pump.
• 6. The springs in the pump will naturally try and push the pump pulley CCW (looking at the pulley face from passenger fender) and this will cause it to not line up with the belt that is perfectly aligned with the crank at TDC. As you will see it is halfway between teeth on the belt without touching it. Grab the pulley and turn it CW just enough to line up with the next slot on the belt. Remember to keep the tension near the tensioner as well so it does not skip down below.
• 7. With the tension now on the pump pulley and in your hand near the tensioner, get the belt up and around the tensioner.
• 8. With all of the slack being pushed up towards the cam shaft, grab the cam pulley and slide it in to place. It will fit in the big slacked area at the cam shaft.
• 9. Slide the cam pulley on to the end of the camshaft, and install the cam pulley bolt finger tight.
• 10. Tighten the tensioner CW until sufficient.

[92EcoDiesel Jetta]

naw naw naw you guys is doing it all wrong eh? You must do the easy way, and get all of the slack to the tensioner and cam shaft pulley area.

Here is my step-by-step for putting a belt on, perfectly, every time.

• 1. Get the crankshaft to TDC (like it should ALWAYS BE FIRST when you remove a belt)
• 2. Remove the cam pulley all together. Lock the cam shaft at TDC (which also should still be at TDC from when you removed the belt )
• 3. Lock the pump at its TDC. Keep the pumps pulley on.
• 4. Put the belt on and get it snugged and seated properly on the crankshaft pulley.
• 5. While keeping tension on the side that goes up towards the tensioner, so we do not skip on the crank pulley, start the belt up around the intermediate pulley to the injection pump.
• 6. The springs in the pump will naturally try and push the pump pulley CCW (looking at the pulley face from passenger fender) and this will cause it to not line up with the belt that is perfectly aligned with the crank at TDC. As you will see it is halfway between teeth on the belt without touching it. Grab the pulley and turn it CW just enough to line up with the next slot on the belt. Remember to keep the tension near the tensioner as well so it does not skip down below.
• 7. With the tension now on the pump pulley and in your hand near the tensioner, get the belt up and around the tensioner.
• 8. With all of the slack being pushed up towards the cam shaft, grab the cam pulley and slide it in to place. It will fit in the big slacked area at the cam shaft.
• 9. Slide the cam pulley on to the end of the camshaft, and install the cam pulley bolt finger tight.
• 10. Tighten the tensioner CW until sufficient.

I did exactly your procedure except part of step 6 where I did not turn pump sprocket CW before slipping belt on. I will try that next time.

The good that came out of this last exercise was that I found a way to get the belt off the pump, re-index it and back on w/o pulling the cam sprocket ànd disturb its timing relative to the crank.