Rick Carter

This is my delay to tuning with the SMT-6. This is all I have to say about it now. I won't answer any questions until I have more info. I've posted this for educational purposes.
Rick
85 32v modified

Below is Louie Ott's reply.
Thanks for the pics. That is a real shame. Sorry it happened. I've often
wondered about the serviceability of that feeble little bushing. One
thing that I have observed is that the T belt doesn't need tensioning
after the first 2k miles or so. Not to say it shouldn't be checked. If
it does need to be tightened, something else is wrong that made it
loose. It could be the water pump bearing or as this shows, the
tensioner arm. The belt doesn't stretch after initial wearing in.

Louie


Here are some pictures of the bushing in the tensioner arm that failed causing all the damage. The pictures arent the best, basically the bushing cracked and ovaled out which alloud the tensioner to rock in relation to the rest of the pulleys pushing the timing belt forward into the tensioner bracket (thats what the shiny silver grooves in the arm are, the belt cut them in)

http://www.lasotaracing.com/carter/broke/ten1.jpg
http://www.lasotaracing.com/carter/broke/ten2.jpg
http://www.lasotaracing.com/carter/broke/ten3.jpg
http://www.lasotaracing.com/carter/broke/ten4.jpg
http://www.lasotaracing.com/carter/broke/ten5.jpg

Here are pictures of what it looked like with the belt still on it, you can see how the pulley is cocked at an angle to the crank pulley...

http://www.lasotaracing.com/carter/broke/al1.jpg
http://www.lasotaracing.com/carter/broke/al2.jpg
http://www.lasotaracing.com/carter/broke/al3.jpg
http://www.lasotaracing.com/carter/broke/al4.jpg
http://www.lasotaracing.com/carter/broke/al5.jpg


And this is the end result

http://www.lasotaracing.com/carter/broke/result1.jpg
http://www.lasotaracing.com/carter/broke/result2.jpg
http://www.lasotaracing.com/carter/broke/result3.jpg

The driver side head has all the exhaust valves bent severely, the passenger side isn't as bad, but they still need all new exhaust valves and guides...

bunch of Porsche valvetrain parts... http://www.lasotaracing.com/carter/broke/parts.jpg

Thanks!
Rob LaSota

heinrich

Well I am really sad to hear that. I'd like to help.

ErnestSw

That's downright UGLY!!
Sorry it happened. I wonder why the tensionser warning didn't happen.

Big Dave

Perhaps this is an opportunity for someone to develop a better bushing.

Rick Carter

Heinrich,
Cost effective sourcing valves, guides, belt and other parts is what I think I need now.
Thanks,
Rick
85 32v modified

heinrich

I think I can help.

Big Dave

Rick:

I did this rebuild last winter on my '85. If you run into problems, let me know. I may have encountered the same stuff already.

I do have a few items left over from my rebuild, but not much. If you make a list of what you need, I'll see what I have. A lot of people generously donated spare parts, so I'm happy to pass along anything I have that you'll need.

Jim_H

Sorry to see that Rick. Please don't quit on it, it will be better than ever after you fix it.

Big Dave

I should also mention that I made a small guide to some of the process. You can find it HERE

heinrich

Tough one. They do tend to work and last very long. A bearing would be the bet solution or actually a whole different tensioner, more like conventional ones, ie sprung.

Jim_H

A small guide Yeah right, Tony V would be proud

Tony

Whoa. Tell me this isnt the SC car..but a different one...please!

Garth S

Rebuilt my S4 tensioner ~2 years ago using 'home made' tensioner bushings turned out of delrin rod stock: made them with a longer throat support area, tighter 10mm fit, and a grease groove - packed that with a high tack grease. No trouble yet ....
Thought of machining the tensioner arm to accept two bearings ..... still on the to-do list, but am not confident bearings would survive on such limited rotation ( only ~5 deg of swing).

Bill Ball

Unf*ing-believable! That little plastic bushing did all this?! That bushing is a bit of a pain to replace. The old one will usually come out fairly easy, but the new one won't go in easily at all. You have to press it in just right and with care to avoid cracking it. It's a learned skill. So, many people take a look at the old one, conclude it is OK and put it back in.

Rick, you'll get loads of support here for the head rebuild. Looks like your shop is fast at getting things apart.

Imo000

This is EXACTLY what happend to me last summer. However I managed to dodge the bullet. The T-belt was half shredded. The passanger side cam gear jumped 3 teeth and the driver side 4. I've replaced the T-belt with a new one and was amazed that none of the valves were bent. The problem was the same thing. The 2 bushings were worn and they pushed the belt off the gears. The water pump pulley ended chewing up half the belt before it jumped. I went to the local Porsche dealer and ordered a new tensioner roller but not the busings,they wanted over $50cdn each. The 16V bushngs are jsut $2 each however the 32V ones are $50. 928 Int. had a much better price and since the hood shocks were on sale I orders them too.