Tenpoundburrito

Hello, Everyone;

I am starting this post because I am having some difficulty with properly tensioning the timing and balance shaft belts on my 944. I have a 1983 Porsche 944 that I bought last year. I read a lot about the belts, how often they need to be replaced and have the tension checked, and how to replace them. Since the car's odometer broke (surprise), I decided to replace the belts this spring after the temperature warmed up. I also went into the engine to replace the cambox gasket since it was leaking near cylinder four. Two birds, one very long day. I purchased new belts from Beck-Arnley, along with the flywheel lock and an Arnnworx 920X V6 belt tension tool that I got for Christmas from my wife. I followed the instructions for everything from Clark's Garage and Arnnworx.

The problem arrived as I was reassembling everything. I put on the new timing belt and pretensioned it using the 90 degree twist method to get it close so I could fine-tune it with the Arnnworx tool. I followed the instructions that came with the tool to verify that it was properly calibrated, then put it on the belt. The instructions say a new timing belt must be tensioned between X90 and X97 on the tool. For those who don't know, the tool works backwards; 90 is tighter than 97, for example. But when I put it on the belt, it's reading about 40. Completely loosening the tensioner takes it to around 70, while tightening it until you can barely twist the belt at all only gets it to 30.

I attempted to contact Arnnworx, but the contact section of their site is down and Bruce Arnn's e-mail server is rejecting mine and delivering a failure notice, so I have no way to contact him.

Has anyone else experienced a similar problem with this tool? I tried several times and double checked the instructions to make sure I was doing this correctly. Is there something I'm missing? Perhaps another tool besides the ridiculously expensive Porsche P9201 tool? Any help would be appreciated, as I have been looking forward to driving this car all winter and was hoping to have it on the road soon. Thank you!

The Forgotten On

If no one knows how to fix your problem you can rent the P9201 tool from Vertex. https://www.vertexauto.com/porsche-b...al-p-9667.aspx

curtisr

Anything here of value? Arnworx Tensioning Tool Question

Tenpoundburrito

Thank you both for the replies so quickly.

I checked the thread on the guy who has a calibration issue with his. The one that Arnnworx sent me has the bar which is marked on one side. It has a sticker that says X63 and to face that side away from the gauge, which is how I used it. One person in the thread says this bar is used to zero the gauge, but the instructions say it's to set the gauge to X63 like on the sticker. Could it be a misprint? Or am I supposed to put the bar in, make sure it says X63, then reset the gauge to 0? And if so, do I reset it by rounding up or down from X63?

I checked the rental for the Porsche tool, which is a lot more reasonable than buying the tool outright. I didn't know you could do that. Thanks for the link. I'm assuming it's $150 to rent the tool and you get the $500 core charge back upon return, correct? I could feasibly use this to reset the Arnnworx tool or check it in foot-pounds against another tool. That way I'd be able to retension the belts at the appropriate intervals later on rather than paying to rent it again.

Which brings about another question: has anyone measured these belts in foot-pounds rather than the units on the Porsche or Arnnworx tools? I could easily get a belt tension gauge in foot-pounds from one of my local shops for

PaulD_944S2

Did you try calling Bruce at Arnnworx?
He's easy to get a hold of and would have your answers.

Heck, I even got the phone number for you: 636-285-0080

Spring44

A foot-pound (or pound-foot) is a measure of torque, not tension, and therefore would have no bearing in measuring tension. Tension is just measured in pounds, like a heavy weight suspended by a rope.

Our tensioning tools measure belt deflection over a certain length of belt and this is an indirect measure of belt tension. That amount of deflection is empirically correlated to a number on the dial of the instrument so it should be calibrated periodically to assure consistent readings. The numbers on the dial are dimensionless numbers and are only indicators. Porsche has made an educated estimate as to how much tension that it will take to keep the belt from jumping a tooth and have given us a range of instrument readings (new belt-old belt) that will keep us out of trouble.

michael7810

I also could not figure out the Arnworx tool which was frustrating AF. I ended up using the twist method for both belts. What a waste of money.

Rensb

I hate to say it, but that's exactly what I did. The tool just didn't seem right>

Tenpoundburrito

Thank you all for the ideas.

I tried calling the number on a couple different days during business hours, but all I get is ringing followed with a message stating that I don't need to dial long-distance to connect with that number. When I attempt to dial local (this is a Michigan to Missouri call), I get the message stating that I do need to dial long distance. No voicemail or anything, but thank you for the idea anyway.

Also, thank you for the information regarding tension versus torque. I didn't know that. I was assuming they were the same thing because I saw a couple that seemed to be measuring in foot pounds like a torque wrench.

I worry about using the twist method because it seems so inconsistent. For example, I have a messed up thumb. I currently cannot twist the belt to ninety degrees when my father, who was a mechanic many years ago, can quite easily. My brother, however, who is in the military, can twist it past ninety degrees. Therefore, our ninety degrees twist method is quite varied between the three of us. Which is correct and how do we know? That's why I would prefer to use the tool.

Are there any other tools that have a measurement specifically for the Porsche 944 like the Porsche and Arnnworx tools?

PaulD_944S2

Here's Bruce at Arnnworx 's own words on using the belt tensioning tool. The best way to contact him is email: BruceArnn@arnnworx.com


First off, if you haven't looked at the videos yet do that. They are right at the top of this page...http://www.arnnworx.com/new_tensioning_tool.htm
Depending on your browser, you can run these wmv files from the link or you may have to download them first and then run them.

Now on your questions: Zero doesn't mean anything to the 920X. Put the cal bar in place, oriented like the sticker says and twist the outer ring (either way) till the big needle points to the the cal value (its written on the bar). Pull the cal bar. Now its ready to go. There is no zeroing of the gauge.

Also, just like the P9201, you have to aware if things can come in contact with the tension tool. If you see impossible readings then the tool is probably pressing against something on the engine that is distorting the reading.





Next you have to control the belt's slack, I would love to just skip this but then we would be just guessing at the tension and it could be way off. Put the tool on the upper span, check for contact between the tool and surrounding engine parts (just like the P9201) and slowly (almost not moving) turn the crank counter-clockwise just a tiny amount. The cam springs will resist movment and belt's slack will move to the upper span. You can thumb it like a guitar string and feel the difference. You can watch the needle but really all you have to see is the arch shown in the pic above. If no arch or a huge arch - either your belt is way too tight or too loose for us to even begin. No big deal though, pull off the tool, back the crank up a hair (CCW) to TDC and tighten or loosen the cam belt.

After the adjust, turn the crank counter-clockwise a tad again (to orient the slack). Put the tool on the upper span again and see the arch.

Now you're ready to make the real belt adjustment.

Bruce

BTW, Bruce is looking into the phone issue, however he prefers email for any of your questions or comments.

Tenpoundburrito

Thank you for the e-mail and the link to this help site. I have tried e-mailing him at this exact e-mail three times in the past week. Every time I have received a "Failure to deliver" notice stating that his e-mail is unreachable.

I looked over the videos and the pictures in the instructions before and during installation of the belt tool. We have the bar correctly calibrated, with the X63 sticker facing away as it states. I also checked the bar on a flat surface and it does not appear to be bent. When we installed the gauge on the belt, we made sure it is oriented correctly, with the metal flats on the flat side of the timing belt and the roller pin settled in between two of the belt teeth. We also made sure it was not contacting anything else on the engine (hard, but not impossible). We also made sure to transfer all the slack to the long span between the camshaft and crankshaft gears.

Ironically, this picture from the instructions shows exactly what I'm reading on my gauge at home:



My gauge is reading between 30 and 40 after using the twist method. However, the instructions included with the gauge say a new belt should read between 90 and 97. That's my confusion. I keep wondering if the instructions were just incorrect. Or if it's the belts I'm using, which are Beck-Arnley belts, that could be changing the reading for some reason.

Again, thank you for helping me with this. I really appreciate it, and I know that I will get this figured out and have my Porsche on the road sometime soon.

PaulD_944S2

Can you post a picture(s) of your belt routing?
Also, would you be able to put your old belt back in to test the tensioner, just in case the new belt is wrong sized or defective?

Tenpoundburrito

I will see what I can do. I don't have internet at home, so I have to use it in public areas, and they don't always allow me to plug a flash drive in. It may be a bit before I can get them posted.

I feel like an idiot, because what I should have done was checked the tension on the old belts using the gauge before I removed them. I could have used that as a base reading to see where the gauge was before putting on the new belts.

The new belts appear to be an exact match for the old ones. We checked them once we had the old belts out. All of the teeth lined up and the lengths were almost exactly the same. The old belts didn't appear to be very worn at all, and they were changed (according to the broken odometer) around 10,000 miles ago. However, according to the Carfax report, that was also almost fifteen years ago. I would have left them except we had to do the cambox/valve cover anyway. It was running near-perfectly, just dripping oil on the exhaust manifold at cylinder number four and having a little trouble with airflow (mouse nest with a dead mouse in it in the air filter box).

PaulD_944S2

Bottom line, if it was my 944, I would set the belt tension to 90 degree twist, and then recheck/retension in 1000 miles, and move on to other repairs/upgrades.

I think the biggest failure is that owners do not retension the belt after it has been run for awhile.
The Porsche service manual makes rentensioning a requirement of the belt replacement.


"The old belts didn't appear to be very worn at all, and they were changed (according to the broken odometer) around 10,000 miles ago. However, according to the Carfax report, that was also almost fifteen years ago."

Incidentally, I once drove a 924S from Portland to SoCal (>1000 miles) that had a 17 year old timing belt with 24,000 miles on it. When I got home, I changed the belt even though it was in good condition, and the tensioning was still in spec. I think it's more mileage than age that affects the belts. However, your changing the belts while doing the cam tower was the right thing to do.

Tenpoundburrito

Thank you for the suggestions. I really like this car and I want to keep it as long as I can drive, so any good advice is welcome. The car was an amazing deal; I don't really have many repairs to it once the belts are done. The only issues are the driver's seat stitching and steering wheel stitching have come loose in a couple places, and it needs new tires (already have some) and an alignment.

As far as upgrades, it will only be very basic stuff. I bought a K&N high performance air filter to replace the old one with the mouse nest, and I plan on upgrading the lights to LEDs for safety (lots of deer where I live), adding mudflaps if I can find them to protect the rocker panels, and maybe replacing the muffler with a free-flow one.

Again, thank you all for the assistance on this.