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Timing Belt Guides and Tools


Owning a 944 pretty much means knowing something about the timing and balance belts. This page is intended to provides some insights on tools & methods for setting the belt tension. Its funny how these belts exist in countless other cars but on the 944 they take on a whole new level of dread. Some feel the belt failures are the 944's Achilles heal while others see them as no big deal. No matter where you stand in this mix,  there is no question that the 944's belts require a bit more maintenance than other cars.  

First, getting access to the belts is a challenge in itself.

 

Above is a drawing of the belt layout used in the 83 through 86 944. Porsche recommends these belts be replaced every 30,000 miles and be re-tensioned at about 1500 miles following replacement. Porsche offers a couple of tools to set the belt tension and you should be able to pick these (below) up at your local dealer for $600 to $700. If this seems reasonable, get the maintenance manuals while you're there (for another $400) and forget about trying to do this little job on the cheap. 

  

If you're interested in a different approach and saving a few bucks then read on. Items 1 & 2 above are the functional equivalent of this little tool known as the Krikit. 

The Krikit is an ingenious little device that can quickly and accurately determine your 944's belt tension. I don't have exhaustive studies or lab analysis to back up this claim but I am convinced that it works and since so may others have recognized it as an alternative, I offer it for your consideration. This page is meant to help you to know how you might use it. You should also be familiar with the specifics for setting your belts - I'm only touching on  the general steps  here to demonstrate the tool. Here is a link to Clarks Garage and a step-by-step procedure for tensioning. 

First, here a couple of photos of how to orient the Kriket along the belt. Above photos are of the cam belt and the balance belt. Note that on the photo of the balance belt, the contact portion of the indicator arm is directly over one of the belts nubs.  This is important for an accurate reading. When you apply thumb pressure you will see the indicator arm raise up and a click can be felt/heard. When you feel this click, immediately release the pressure and read where the indicator arm intersects the scale.

The above reading is 27 Lbs and very close to the correct setting for the 944 balance belt. Side note: when I first used with this tool, I was concerned that the Krikit would not accurately measure below the lowest scale mark of 30. But in testing with it, I found the tool to consistently measures down to as low as 26 pounds.  If you haven't used the tool before, you should make several readings (without altering the belt tension) until you begin seeing consistent readings - it only takes a few tries to get the hang of it.

 

Now, on to the actual belts. The ideal place to measure belt tension is at the center of the longest span. To create a long span,  I have removed the upper timing cover (for access), the timing belt idler pulley and water pump guide rail (available only with the updated water pump). Notice how that when I apply thumb pressure through the Krikit, that there is a space (see arrow) between the spanned portion of the belt and the other area of the cam belt. This small space is important, without it, you will not be accurately measuring the belt's tension. 

The Krikit quickly tells me that my timing belt tension is correctly set at 40 lbs.  I make a this reading a couple of times to be confident that I am getting a good reading. If the reading is low or high, I make the needed adjustments and use the Krikit to make another reading. Note too, how easily the small size of the Krikit works to fit into this very tight area.

  

I haven't mentioned it but you should have your cam positioned at about a tooth before TDC. If you're making changes to the the timing belt tension, it's best to rock the cam by a couple of degrees each way and then back to the 1-1/2-tooth-before-TDC position. Then recheck the tension using the Krikit. This rocking ensures the belt tension is distributed evenly around the belt. The rocking is not needed though for adjustments to the balance belt.  My photo above is only meant to show the different marks. In this photo, the marks are not correctly aligned. 

Above, you can see my attempt to get a reading of the balance belt. As before, I've removed the balance belt idler roller to create a long, unobstructed span. In this case my tension was so low that I got an invalid reading. This is apparent because the indicator arm is extended against the stop, see below.

This was easily changed by tightening the balance belt tension and simply rechecking with the Krikit. I then rpeat this tighten, then measure cylce until I had the correct tension. Most people are surprised at how loose the correct tension on the balance belt is. I've found that it should be no higher than 28 pounds else there is a distinct (and irritating) belt whine. With that, I re-installed the idler roller and prepared for a engine-running inspection of belt operation.

With the balance belt re-tensioned, I only need to get the idler back in place before starting the engine.  Here you can see that I'm re-setting balance belt idler roller to the specified .5mm - it should not actually touch the balance belt.  

These photos make the access appear easier than it actually is. Working in this tight area is a pain, but you'll get the hang of that too with a little patience. You can see here (above) that I'm using an older version of one of my roller wrenches.  This is because a standard wrench will not fit, at least not from many approach angles. What's worse, as you tighten the anchor nut, the off-center, adjusting nut tends to turn along too and alter your carefully chosen setting. Click here to order your Krickit Tool and Timing Belt Wrench Set

 

 

Other Notes:

This is the belt layout for many others of the 944 series. In the center is a device known as  an auto-tensioner. This will auto-magically set your timing belt tension. You'll need the Krikit (or something similar) for setting the other belts though.

Above, I mentioned the Porsche recommendation for belt change intervals. There is some controversy concerning how often the belts should be changed, Gates (a company who make belts) recommends a longer interval. This clipping (below) is taken from Gates' manual on  recommended belt change intervals.  

 

One last note about the AC and power steering belts.  The Krikit can also be used on V-belts. I've found that Krikit readings of 50 for the AC and 40 for the power steering to be sufficient for my street driving.  That is on the low side for some though. 

If you check your V-belt tensions, remember, check along the longest span. For the AC this is between the AC compressor and the crankshaft. Either span of the Power steering belt will work equally well.



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