Timing belt tensioning

[tstark]

Finally got the parts I needed to finish my project. But I have a question about the timing belt tensioning. I read Clark's and it says to start at the crank gear and take the belt around the cam gear and leave no slack.

The belt is fairly taught between the crank and cam gears. I'm thinking its too tight, because when I try to adjust tension with the Arnnworx 920 v.6 the gauge moves lower, rather than higher toward the proper range. The FAQ states that a lower reading is evidence of too much tension.

Question: when initially installing the timing belt how snug should it fit between the crank and cam gears? Should there be some deflection in the belt span between the gears?

Notice in the picture the the tension between the crank and cam gear. Also that the belt does not seem to fit completely around the cam gear gear.

[944tothefloor]

If you haven't, you need to rotate the engine a few turns by turning the crank clockwise, to distribute the tension on the belt. The water pulley side of the belt looks loose, and the way the teeth are coming off the cam gear is a little suspect. Otherwise, nice job, youre almost done.

My opinon is: Get rid of that tool, I wouldnt trust it. Use van's videos on youtube (if u can't find them someone will post a link).

[mytrplseven]

A certain faction of us use the tightening method of tightening until you can barely turn the water pump pulley by hand. Hand turn the engine a few turns and re-check and adjust as necessary. I've used this method successfully on 3 different cars. Re-tension after 1000 to 1500 miles.

[tstark]

Originally Posted by 944tothefloor

If you haven't, you need to rotate the engine a few turns by turning the crank clockwise, to distribute the tension on the belt. The water pulley side of the belt looks loose, and the way the teeth are coming off the cam gear is a little suspect. Otherwise, nice job, youre almost done.

I'm at TDC with the flywheel lock installed. Are you saying I need to remove the flywheel lock, rotate the crank, find TDC again, then tension the belt?

[tstark]

Originally Posted by mytrplseven

A certain faction of us use the tightening method of tightening until you can barely turn the water pump pulley by hand. Hand turn the engine a few turns and re-check and adjust as necessary. I've used this method successfully on 3 different cars. Re-tension after 1000 to 1500 miles.

As it sits I can barely turn the WP pulley or rotate the belt 90 degrees. If I tension tighter to get the belt seated around the cam gear, I won't be able to turn the WP pulley. Should I leave tension as it is in the photo, then turn the crank to seat the belt on the cam gear?

[944tothefloor]

Originally Posted by tstark

I'm at TDC with the flywheel lock installed. Are you saying I need to remove the flywheel lock, rotate the crank, find TDC again, then tension the belt?

Not exactly. If you have everything lined up, ie the belt is ready to go, you can remove the lock. the belt will keep the timing in place. And yes, you should tension the belt with the flywheel lock off, as I understand it, so you can be rotating the system whenever you need.

Otherwise, one portion of the belt tends to have greater tension than the other portion, so your tensioning -- whatever method -- will be useless.

Really, you may want to see Van's videos. he goes through several checkpoints to ensure proper tension, such as the "spinning WP" method, "twist" method, clearances, and even the harmonics of a properly tensioned belt. Good stuff.

[944tothefloor]

^^^ needed to mention you should have both belts on before removing the lock.

[tstark]

I've watched Van's videos on WP and timing with auto tensioner. Haven't found one with the methods you mention. Anyone have link?

[mattdavis11]

make sure you rotate the eccentric counter clock wise when setting tension on the belt.

BTW, who made that cam belt? It doesn't look right, and I've had one look very similar.

[tstark]

make sure you rotate the eccentric counter clock wise when setting tension on the belt.



BTW, who made that cam belt? It doesn't look right, and I've had one look very similar.

Continental belt. Teeth aligned with old belt.

[944tothefloor]

Porsche 944 Turbo Water Pump Change - part 1.wmv - YouTube

there are 3 parts. the tensioning process is in one of them.

[speedysprocket]

Sure it's not a belt meant for a twin cam engine? They're wider than an 8 valve belt and the number of teeth is different.

[tstark]

Sure it's not a belt meant for a twin cam engine? They're wider than an 8 valve belt and the number of teeth is different.

Will double check. Thanks.

[tstark]

Originally Posted by speedysprocket

Sure it's not a belt meant for a twin cam engine? They're wider than an 8 valve belt and the number of teeth is different.

Measured the belts, same width. I'm thinking once the slack is taken out the belt should be fine. So I'm planning on putting the balance belt on and lining everything up, removing the flywheel lock, turning the crank 2 revolutions to remove slack, then tensioning.

[944tothefloor]

Thats it. Rotate and tension a few times until you have a tension that is constant. Rotating is also so the belt is rolling straight over everything and not hanging off a gear or roller.

[kdjones2000]

You don't need the balance belt in there, just have the timing belt with some tension on it before turning and you will be fine.

[tstark]

Thanks everyone. Been busy with work but will knock this out this weekend!

[Slam]

Remember to remove the cam belt idler. You've got yours installed and it sits right where you wanna be checking tension. Have fun!

[tstark]

Originally Posted by Slam

Remember to remove the cam belt idler. You've got yours installed and it sits right where you wanna be checking tension. Have fun!

Finally got the slack out of the belt from cam gear to water pump. Can just barely turn the water pump pulley. Tried using the arrnworx tensioner but readings say consistently say its too tight, even prior to removing the slack. Maybe it's because I'm checking at the wrong point. Will remove timing idler roller and try the gauge again.

Here's a pic of the cam gear. Should have taken a better before pic. Can't tell if the belt is seated around enough cogs on the gear.

[944tothefloor]

I think everything looks good. Nice job! Maybe it just the view, or the shadow, but it's worth noting that that belt tooth hanging off, on the right side of the cam pulley, looks good -- not great, but good.

As they say, you should be able to turn the pump with one hand with considerable effort, but it should take little effort with both hands.

Make sure everything else is all set.