87 spring timing belt tensioner

[djnolan]

I had the belt cover off for the first time in quite a while. Concerned the belt was too tight as I was unable to spin the water pump pulley by hand. My experience with timing belt tensioning is using the twist method on an older non-spring tensioner models.

What is the best way to adjust the spring tensioner types?

[I just went over 1000 posts]

[mikepellegrini]

The spring tensioner sets the tension automatically.

To re-tension, just loosen the set nut and then retighten. Timing Belt and Balance Shaft Belt Tensioning

It's probably just fine.

[mytrplseven]

I have an '87 as well and even though I have a spring tensioner, as old as it is, I didn't want to trust that it would be accurate. I reset the position of the bracket so I could get the proper "feel" tension, just as you do. Works fine for me.

[v2rocket_aka944]

Set the tension by the twist method still. Don't trust the spring tensioner, they are widely varied in their usefulness due to age of the car..

[jeffrsmith]

Is there a procedure on how you do this with the spring tensioner? FSM procedure on how to use the spring tension is pretty straight forward.

[v2rocket_aka944]

Let the locknut loose and let the spring push the belt, check tension, and lever the tensioner tighter or looser if needed and lock it down when the twist test passed

[mikepellegrini]

Everyone makes too much of tensioning the cam belts. My favorite cam belt tensioning thread, from Clark's Garage: http://clarks-garage.com/phpBB2/viewtopic.php?t=1935&highlight=twist

A summary of that thread: Starting out, Porsche hadn't specified any particular values for tensioning cam belts on 944's - the belts were all set by "feel." After a few years, there had been quite a lot of belt failures. These early belt failures were more due to poor belt design in the early 80's and lack of proper inspections (Porsche hadn't clearly specified inspection intervals) than anything else.

Porsche over-responded and as a great example of over-engineering, came up with the 9201 tool.

Modern belts are much more durable than those original belts from the 80's.

As long as you get it close and inspect it at regular intervals, you're just fine.

All deference to you, V2, but this ain't rocket science. Close is ok.

[djnolan]

My initial concerns is that the belt seems overly tight and is going to cause excessive wear on the water pump bearing. This is since the pulley could not be turned by hand.

Is it possible the spring mechanism is gunked up and sticking or is it probably just too tight?

[mikepellegrini]

That's possible. Typically, with age, springs will lose their "springiness" not get tighter. So if the assembly is running on the high side, perhaps it is simply gummed up.

I would think if you loosen the set nut and you're able to move the assembly, then you're in the ballpark - where ever it lands. Because of the age of the spring, you'd think it'd have to be looser than Porsche intended. Even if you can't turn the waterpump. So it oughta be okay.

To check it, you can do the "twist," per Clark Fletcher:

At the midpoint of the longest run of the timing belt between the camshaft sprocket and crankshaft sprocket, grasp the belt between the thumb and forefinger. You won't be able to get at the exact midpoint. Somewhere near the cam belt idler pulley will be fine. Twist the belt with your thumb and forefinger only. If you can twist the belt 90 degrees that's perfect. If you can't twist it more than 45 degrees without a great deal of effort, it's too tight. If you can twist it more than 90 degrees with ease, it's too loose.

If so, you're good to go and I wouldn't stress about it.

[John_AZ]

More WSM UPDATE info on spring tensioner...

[v2rocket_aka944]

gotta love their improvised methods.

[DannoXYZ]

So if I:

- use a finger than my thumb to push the belt against the belt-cover or
- push it only 1 time? or
- push it 3 times?

Then my belt's gonna explode and grenade the engine?

[Slam]

Absolutely. It's all part of Porsche's plan to deprive us of blissful slumber...

[9FF]

Originally Posted by DannoXYZ

So if I:

- use a finger than my thumb to push the belt against the belt-cover or
- push it only 1 time? or
- push it 3 times?

Then my belt's gonna explode and grenade the engine?

Itz sayz usen yours thumb two times you dumbkopf. Ze rules must be obeyed or elze there vill be consequences.

[djnolan]

I am doing further analysis of my 944S near death experience when my timing belt idler pulley disintegrated, without otherwise causing damage. I am wondering if a stuck spring tensioner caused it.

The spring tensioner adjustment check described in the Porsche service bulletin above says to loosen bolts A & B and push on the belt where the arrow is. I did this and the tensioner moves freely.

I tighten it back up and try to move the tensioner and it won't budge. Is this normal?

Should the spring be that tight?

Engine is warm now so I can't check it with the thumb method but plan to when it is cold.

A gentle reminder to those who neglect their timing belts:

[dgcantrell]

I doubt that the spring tensioner had anything to do with that idler exploding like that. Moving the spring tensioner with your hands without some type of leverage is pretty damned hard unless you're some Superman type. I let the spring tensioner handle the timing belt and I use the twist/feel method on the balance shaft belts and haven't had belt fail yet that wasn't the result of a one of the pulley bearings letting go. Also, a new belt is going to grip the waterpump pulley pretty well. If I were able to turn it by hand with the belt on it, I'd be concerned that it wasn't tight enough and would slip under a load. This will heat up the belt even more.

[djnolan]

I couldn't budge it even prying with a wrench on the 17mm roller bolt once the bolts A & B were tightened. This seems to tight if the spring wont compress.

[dgcantrell]

Loosen them a little more..

[djnolan]

I think the question I have is do you tighten those bolts A&B while pressing on the Belt against the belt cover or tighten a/b after you release pressure on the belt?

[Rasta Monsta]

Pressing the belt just verifies that the tensioner is moving freely. Loosen A&B, press the belt a few times to observe the tensioner arm doing its thing, and then tighten A&B.