Engine Rebuild Belt Question

[BimPorDuc]

I'm new here but not new to the 944. I drove one daily for three years in the late '90s. Now we've got another one - an early '85. It developed a knocking noise after an autocross. You guessed it - bad rod bearings. I thought it was lifters - Duh-Oh ! I put in a cam tower, lifters, and cam from an '87. The noise hung around. I drove the car until is seized. Now I'm looking at a replacement engine from an '88. At least I keep going up in power 143, 147, and soon 158 bhp.

My question is about belts and there are hundreds of posts and threads on this I know. The tool of choice seems to be the 9201. I've seen them used. There is the kricket too for getting in the ballpark. I've changed belts on a few VW Rabbits / Golfs and successfully used the "twist" technique. That's listed here for the 944 too along with "just" being able to turn the water pump. Now there's a newer Arnnworx tool: 920Xv6. Has anyone had any experience with it? The old 9131 looked kind of crude. I can see doing a gauge R&R to correlate the Arnnworx 920Xv6 with the 9201.

There's also a tool from Gates called the 507C Sonic meter. It measures the resonant frequency of the belt when plucked. It's pricier than the 9201 but I may have access to one at the shop where I'll be prepping the engine for may car. Has anyone tried that tool? I've seen technicians that have experience with hundreds of 944 belts pluck them and listen to see if they're close.

+1 on a post I saw about the Arnnworx 24/27 mm wrench and the need to cut it. The individual versions (e.g. 9244 tool) sold over at RennBay or 944Onlone are a much better way to go. Any feedback is appreciated.

[ryancolindres]

I just did the belt on my 84 944 and I used the cricket tool from napa. I had a 944 friend and he owned 3 944's and did many timing belt changes and always used the cricket tool and never had a failure. He helped me do mine and its been fine.

[Guest765]

Those tools are a waste of money for the 944. Many will argue with me on that, but I did two timing belt changes before my car was totaled in an accident and I never used anything but the wp pulley test. I guess it can make you feel better to use the tool but I just couldn't justify the cost, especially after reading about the unreliability of the tool if not used perfectly.

Edit; pardon me, make that three tb changes, I forgot I replaced it a third time when I did the oil cooler seals because I had an extra belt laying around.

[John_AZ]

If I understand, you will be putting a '88 engine in the '85 944 that has a seized engine.

You probably know the DME is different for the '88 with 158bhp.

With a new cam belt, use a combination of the methods above.

I use the WP pulley tension method.
It will work well for a brand new belt the first time installed because the new belt needs to "settle" in the gear grooves.

I retension after about 300 miles on a new belt.

I own the Krikit tool and feel it is worthless on the cam belt. I have tried many times to repeat a previous test with the same results and due to the position and finger hold of the tool, it is impossible ----maybe getting close---but I do not like to guess on the cam belt.

The Krikit does get the BB close---because it has to feel sloppy and there is room to work the tool.

The '88 engine will have the "Spring mechanical tensioning roller".
Porsche has put out a couple of tech bulletins updating the procedure to set the tension on the cam belt using this upgrade. It will not give you accurate tension on the cam belt without reading the "updated" tech pages.

It comes down to experience and confidence in the method you choose.

Sleepless, sweaty nights and nightmares of belt failure are just normal.

J_AZ

[Guest765]

Agree with john, I've never heard anything good about that kriket tool.

[v2rocket_aka944]

90* twist for the TB, 180* twist for the BB, credit card fits between BB and idler.

i had a spare 3/4" wrench and ground it to 27mm and narrowed it to fit on the pulleys.

[Volhv]

1 1/16 inch is just a hair under 27mm, and will easily fit. If you have one of those 4 angle wrenches like the snap-on ones, it will be of great use, and does not need to be ground.

[BimPorDuc]

Yes. I'm aware the '88 engine doesn't use the same DME as the '85. However I've been told by a long-time Porsche shop owner / tech that I can move the manifold and idle control over from the early '85 car and then keep the same DME. I also know I need to get the coolant gauge sender from a 924S.

Seems no one has experience here with the Gates sonic resonance tester. A friend will use the tool on the cam belts for a Lexus. I'll report back if I have a chance to use it.

When I did the cam housing back in December I set the belt by "feel" (twist) and then had it checked by my P-tech friend with the 9201 tool. The reading came back at 3.2 which is within range for a used belt.

Yes. I know the range for the sweet spot is pretty narrow. The '88 engine with the later spring loaded tensioner will offer some piece of mind.

Thx.

[BimPorDuc]

Originally Posted by Volhv

1 1/16 inch is just a hair under 27mm, and will easily fit. If you have one of those 4 angle wrenches like the snap-on ones, it will be of great use, and does not need to be ground.

Has anyone tried a 27 mm Snap-On Crow's Foot? I think I'll just invest in the 9244 sold over at RennBay. I used one back in December when I did the belt retension after doing the cam tower.