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What else to do when timing belt is being replaced on an S4

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Old 08-13-2017, 03:39 PM
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Socal_Tom
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Default What else to do when timing belt is being replaced on an S4

Shhhhh, don't tell anyone, but an '87 S4 has magically appeared in my driveway.

Timing belt is 10 yrs (under 2,000 miles) old so going to have it replaced, what else is SOP to do when that is done? Water pump comes to mind and belt tensioner rebuild? Car has 94,000 miles on it and has been well maintained.

Since this is an automatic I imaging that checking for thrust washer issues would be smart?

Take me to school if you would please. My last S4 was a manual and I put 40k+ worry free miles on it but it's been quite a while.

Thanks!
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Old 08-13-2017, 03:52 PM
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Consider a Porkensioner instead of the stock tensioner? now with the option of a tension warning connection if you like.

Certainly plan a new water pump (consider the options there - esp impeller type).

Consider the state of the cam sprockets and see if you need new if the wear is already too much.

Evaluate the idler pulleys and bearings.

The air pump may be kaput from a functional perspective (mine was) - so evaluate its state as part of the overall refresh.

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Old 08-13-2017, 04:22 PM
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Hall sensor is much easier to get to when you take off the passenger cam gear and that assembly.
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Old 08-13-2017, 05:07 PM
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Well, they call it the "Timing Belt/Water Pump" (TB/WP) for a reason.

Either rebuild the tensioner (mainly seals & such) or put on a PKT. Which one should you use???

Hoo Boy. Do your own research and make your own choices.

The "While you are already in there" (WYAIT) philosophy is one option. Fixing just about everything that can fail so you don't have to worry about it. Or you can just fix what's clearly bad, knowing you will have to go back in eventually.

Typical things include:

Cam & Oil Pump gears.
Hall sensor
Oil pump seals
Cam seals.
Main (Crank) seal
Coolant pressure sensor (it's up by the reservoir, but you will have the radiator drained, so it's a good time)
Oil level sensor wire boot (usually toast, Roger has a nice replacement for a few bucks)

And lots and lots and lots of cleaning.

Dwayne has a really nice writeup:

http://dwaynesgarage.norcal928.org/
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Old 08-13-2017, 07:17 PM
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Hmmm...what does it look like?
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Old 08-13-2017, 08:22 PM
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Thanks for all of the responses - appreciate the coaching.

The plan is to use it - a lot. Like a lot so will probably just suck it up and dive in / get it done.

I know this is a debate, but do people have a good experience with the alternative tensioner?
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Old 08-13-2017, 08:27 PM
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Originally Posted by GT6ixer View Post
Hmmm...what does it look like?
I know, I know. Pictures or I'm just making it all up.

This is the car we discussed about a month up, she has been well loved.





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Old 08-13-2017, 08:31 PM
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This is the car we discussed about a month up, she has been well loved. Dusty from the trip down, needs a good detail, but a very straight and clean car. Had to replace the MAF and a couple relays, fresh gas, and started cleaning the grounds. Still waiting on a replacement window relay but basically everything came up on it. Typically grumpy running after being woken up but a huge difference after cleaning up the grounds. Good oil pressure and engine seems strong. Not going to run her again until the timing belt is done.
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Old 08-14-2017, 12:03 AM
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Originally Posted by Socal_Tom View Post
I know this is a debate, but do people have a good experience with the alternative tensioner?
Many do. A few have not. The PKT has had a few issues. The bracket has been redesigned.

The original tensioner only adjusts for the expansion/contraction of the block due to heat. It has bellville washers in it that flatten out as they heat up and retract the piston a bit to shorten the path as the block expands and lengthens the path.

It works. It has worked in tens of thousands of cars for 40 years.

BUT...

It has no other self-adjustment. Every modern car (including the 968) has a dynamic tensioner that can extend and retract as needed for what ever reason. No other car out there uses one similar to the 928.

The PKT is an Audi tensioner that comes with a bracket for the 928 motor. It is a "set it and forget it" setup. As long as the piston is within spec on install (and after running it a bit to 'settle' the belt) then you are good to go. The factory tensioner needs to be retensioned after 1500 miles.

The PKT will keep a constant, lower tension on the belt. The factory tensioner needs to be set fairly tight to ensure that it's tight enough. Over tightening it can cause extra wear and even damage.

There are criticisms of the factory tensioner, there are criticisms of the PKT.
Some of the criticisms (of both) are valid, some seem to be "It's not what I like so it must be bad." Some seem to have a personal bias.

Personally, after reading quite a few threads on it, I went with the PKT (85 Euro, 16v motor).

I would strongly suggest doing the same and making your own choices.
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Old 08-14-2017, 12:22 AM
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Originally Posted by Wisconsin Joe View Post
Many do. A few have not. The PKT has had a few issues. The bracket has been redesigned.

The original tensioner only adjusts for the expansion/contraction of the block due to heat. It has bellville washers in it that flatten out as they heat up and retract the piston a bit to shorten the path as the block expands and lengthens the path.

It works. It has worked in tens of thousands of cars for 40 years.

BUT...

It has no other self-adjustment. Every modern car (including the 968) has a dynamic tensioner that can extend and retract as needed for what ever reason. No other car out there uses one similar to the 928.

The PKT is an Audi tensioner that comes with a bracket for the 928 motor. It is a "set it and forget it" setup. As long as the piston is within spec on install (and after running it a bit to 'settle' the belt) then you are good to go. The factory tensioner needs to be retensioned after 1500 miles.

The PKT will keep a constant, lower tension on the belt. The factory tensioner needs to be set fairly tight to ensure that it's tight enough. Over tightening it can cause extra wear and even damage.

There are criticisms of the factory tensioner, there are criticisms of the PKT.
Some of the criticisms (of both) are valid, some seem to be "It's not what I like so it must be bad." Some seem to have a personal bias.

Personally, after reading quite a few threads on it, I went with the PKT (85 Euro, 16v motor).

I would strongly suggest doing the same and making your own choices.
Quite helpful, as always Joe, very much appreciated. Let me get reading.
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Old 08-14-2017, 04:04 PM
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Front engine wire harness. Contact Sean for a repl.
Ign caps and rotors
Belt idler anti-skid bearings(or just remove the cartridge)
Cooling fan harness connectors
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Old 08-15-2017, 01:57 AM
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I have a 928 GTS with a lot of $$$ invested over long ownership. I decided to go with the PKT - it just makes more sense to me. The stock set-up is over-tight IMO - it eventually eats cam gears - not good. I added a rudimentary tensioner warning - I think it is likely about as effective as the stock warning.

I don't take risks I don't think are good trade-offs - too much to lose. But Porsche didn't do everything perfectly - and I think this was one of the things they would have eventually revised to a more modern set-up (if they kept on building it). Every time my tensioner was looked at it was dry - not doing much tensioning.

It's a personal choice issue.

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Old 08-15-2017, 12:46 PM
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Thanks for the additional perspective.

I also wanted to ask, if I am going to have a shop do the work but I want to save them some time and myself some money what should I remove prior to the car being delivered?

Radiator and related coolant hoses etc? What else? Ideas? Don't want the car to show up in bits, not fun/fair to the shop but it looks like there is a fair amount of disassembly required as part of the work.
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Old 08-15-2017, 03:13 PM
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What shop?
How familiar with a 928?

You are right that disassembly/reassembly of all the stuff that is in the way is a big part of the job and it's cost. This can be a very touchy subject.

Some shops won't allow any of that sort of stuff. They will tell you that they won't be held responsible for the work that you do, so if you do any of the work then you are responsible for all of it (once burned, twice shy fits here).

Others will let you come in during off hours (like the night before) and do as much as you'd like right there.

It all depends on the individual shop and your relationship with them. Most shops are closer to the first example than the second.

This is something that should be very thoroughly covered before the car gets there.
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Old 08-15-2017, 03:24 PM
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Before driving at all I would address two things.

Replace all fuel lines.

Carefully and thoughtfully inspect the condition of the insulation on the antilock brakes power feed cable. concentrate on visible section running from block on drivers side, routing behind power strg reservoir on ds fender. Seen these bare before due to insulation failing and falling aeay inpieces. Very very dangerous.
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