Timing Belt Tensioning

lowbob84 · 06-17-2008, 03:57 PM

So I'm tensioning my timing belt, and I have a few questions. First off, I'm using the Arnnworx 920X tool. I've already tensioned my balance shaft belts and I started with everything at TDC (using both the cam gear mark and the mark on the flywheel as seen from under the car).

First, I tensioned everything up and after cranking the engine by hand a few times, my cam gear mark is now about a half a tooth off (as seen below).

Is this normal, is it too far off? While I crank the engine over by hand, I didn't feel like anything was hitting.

Second, after cranking the engine over by hand I noticed the timing belt was sliding further and further back on the cam gear. Does this mean I've gone too tight, or is this normal.

Thanks for the help. I just don't want to proceed any further, until I'm sure everything is cool.

zedsn · 06-17-2008, 04:19 PM

Hopefully other 944 owners will chime in as well. I believe that your half tooth off is ok and when the car warms up the belt will get tighter and come closer to the timing mark. As long as the whole belt is on the cam and crank lobes and not sliding off the end so to speak then in my opinion you should be ok. Wait till others answer though before you go any further though.

zedsn · 06-17-2008, 04:19 PM

Hopefully other 944 owners will chime in as well. I believe that your half tooth off is ok and when the car warms up the belt will get tighter and come closer to the timing mark. As long as the whole belt is on the cam and crank lobes and not sliding off the end so to speak then in my opinion you should be ok. Wait till others answer though before you go any further though.

white944cup · white944cup's Garage

I agree that you are OK on the alignment mark, but your belt should stay pretty much flush with the edge of the cam pulley. From your picture, it looks like the belt is not aligned properly with the water pump roller either. When I did mine, the edge of the belt was lined up with the raised flange on the water pump roller and the front edge of the cam gear. You should have perfect alignment between the crank gear, the cam gear, the tensioner and guide rollers, and the water pump roller. If not, there must be one of the components that is out of line. I would remove the stainless belt guide and not re-install that until you find out where the problem is, and are completely finished with tensioning the belt. Good luck!!

Aufenbahn · 06-17-2008, 06:09 PM

Actually to me your picture looks like the marks are pretty well lined up. I would check and find out why the belt is not tracking properly though.

Sudden thought - is this a new belt? or just a retension?

lowbob84 · 06-17-2008, 06:10 PM

White, from what I can tell, my belt is lined up with the tensioner, but the tensioner seems to be closer to the engine than any of the other rollers. I'll have to check tomorrow if there is a reason why it seems to be misaligned. Thanks guys for the help.

lowbob84 · 06-17-2008, 06:13 PM

This is a new belt. I'm finishing up my head gasket replacement, and I replaced all the belts and rollers.

barks944 · 06-18-2008, 03:16 AM

This is exactly how mine ended up after I did it a few days ago. Been driving great since.

lowbob84 · 06-18-2008, 02:00 PM

Ok.. so I just went out to try and find out why my belt sets back so far as it comes across the water pump and up onto the camshaft gear.

As you can see, the belt runs about a quarter of an inch back off of the water pump pulley than where I think it should be running. So I removed the tensioner roller and saw this.

Does it look like I'm missing something. I mean all I see is a stud with a nut or something all the way against the block. Am I supposed to have something else there?

Also, just to be sure, I'm supposed to install the roller like this:

And not like this:

Also, is there any way I switched the timing belt tensioner with the balance shaft tensioner?

barks944 · 03:12 PM

The first picture demonstrates the correct way to put the tensioner on as you need the big nut to put a spanner on to tension the belt as you tighten the nut on the thread.

The two tensioners are different heights if they are the same as the ones I have. The taller one is the timing belt tensioner iirc.

Edit: My dad was doing this to his 944 this evening, I went out and he's gone to bed so im not sure if he has completed doing so yet. If its still appart in the garage tommorow I will take some snaps for you.

barks944 · 06-19-2008, 04:31 AM

You can take a look at my dads engine here.

http://picasaweb.google.com/tomspics1234/944CambeltEnclosure

He has the same stud and nut next to the water pump.

lowbob84 · 06-25-2008, 04:41 PM

Well, I'm pretty sure I figured this one out. The two tensioners (balance shaft and camshaft) are very similar but have slight differences. And if I'm right, the person who previously did the rollers, put them on back wards.

The cam shaft tensioner has a lip on the gears that, once installed, should be against the engine block. While the balance shaft tensioner has a lip that should be on the side of the gear away from the engine. If you get these flipped, the lip causes the timing belt to slip on the cam gear and it rides too close to the engine (my initial problem). Here's a pic of my old tensioners: timing tensioner on the left, balance on the right.

Cking1975 · 06-26-2008, 05:09 AM

Yes,

Something is off...I have a spring tensioner so it took me a little while to study the diagram for eccentric setup. My concern would be if you ran the car with the belts on incorrectly, the belts may be damaged. Its hard to tell, but it looks like I see a lot of belt dust in some areas, as if something was rubbing, also the tensioners look like they have some wear...I cannot understand why this setup wouldn't of made a bunch of noise ? I may be super anal, but I would pull of of the rollers/tensioners off and inspect them along with the belts...I mean the way I look at things is, it will take you about 4-5 hours and it will be worth every second of time.

lowbob84 · 06-26-2008, 05:31 PM

Well the good thing was I discovered all of this before I finished my headgasket job; the bad, my belts had been doing that for about 10k miles before hand. I replaced the rollers and the belts, so no worries about them having issues. The old belt was definitely worn where it had been rubbing, and belt dust was everywhere. Its a good thing I replaced it or else there probably would've been premature belt failure. As for the rollers, they could've been original. There were places on them where you could see the ball bearings in them. They definintely needed replacing.

So after switching the two tensioners, the belt now lines up well, and there is no rubbing! Whoo-hoo. So instead of 4-5 hours, it was only a couple extra hours of switching the two rollers, and re-tensioning. I've had the car running several times since then. No noise, no slipping, and no rubbing!

Cking, you're right on the money though. Something was off, and I'm like you, I'd rather have it right, than do it wrong and pay a pretty penny later to fix a simple mistake.

Rasta Monsta · Rasta Monsta's Garage

What was your impression of the Arnworx setup?

AKCJ · 06-27-2008, 08:40 AM

Quote:

Originally Posted by Rasta Monsta

What was your impression of the Arnworx setup?

Well, I just did my belts using the Arnnworx tool - it works great. Well worth the $. It isn't hard to use and seems to get the tension set correctly and consistantly.

Of all the choices (no tool, factory tool, arnnworx tool, or other) it's the best choice by a mile.

YMMV

onZedge · 06-27-2008, 09:50 AM

I just used the Arnworks tool to tension my belts after my head-gasket job. After you use it once, you become expert at using it. Elegant in it's simplicity and repeatability.

white944cup · white944cup's Garage

Lowbob: Good find on the swapped tensioners.....as you can see, you need to pay attention to the details when you are working on these cars. If you see anything that doesn't quite look right, stop, take your time, ask questions on this forum, and don't proceed until you know that you are doing the correct thing. If you had ignored that timing belt mis-alignment, eventually it would have eaten through the rear timing cover and resulted in catastrophic failure of the belt and the top end of your engine. Good job..........

lowbob84 · 06-27-2008, 07:41 PM

Thanks White! I feel pretty lucky that I didn't have the belt break before, but I'm glad I got it straightened out. I really would've felt lousy having to redo my top end, after just having doing the head gasket.

Rasta - I really liked using the Arnnworx tool. I went with the Maxikit (~$250 as I recall). It was a little difficult to use the first time, but since I essentially had to tension my belts twice. I felt totally comfortable using it the second time, and it probably took half the time second time around. I would definitely recommend it to anyone. Read the instructions carefully before you start. The first time you use it, take your time. Like onZedge said, you become an expert after your first time!

lowbob84 · 06-27-2008, 07:42 PM

Thanks White! I feel pretty lucky that I didn't have the belt break before, but I'm glad I got it straightened out. I really would've felt lousy having to redo my top end, after just having doing the head gasket.

Rasta - I really liked using the Arnnworx tool. I went with the Maxikit (~$250 as I recall). It was a little difficult to use the first time, but since I essentially had to tension my belts twice. I felt totally comfortable using it the second time, and it probably took half the time second time around. I would definitely recommend it to anyone. Read the instructions carefully before you start. The first time you use it, take your time. Like onZedge said, you become an expert after your first time!