S2 Timing Chain Top Plastic Guide Replacement Procedure

[Mark944na86]

S2 Timing Chain Top Plastic Guide Replacement Procedure

Below is an annotated write-up based on the write-up at:

Cam Chain Tensioner Replacement

It's directed at the replacement of the just the top plastic guide (available from Zims), which is a procedure I did earlier today on my car. My added notes and comments are in square brackets, and in itialcs, [like this].

1. Remove the spark plug wires and spark plugs. If you keep the plug wire holders "clipped" together, it makes it easier to keep the wires in order. Just unscrew the holders and remove the wires as a group. [Actually, you don’t need to remove the spark plugs, but it doesn't hurt.]

2. Remove the xx bolts that secure the cam cover to the head. They do not unscrew all the way out, but they can be pulled through the rubber grommets in the cam cover. Removing the bolts makes it easier to remove the cover itself and reduces the risk of catching a bolt on a cam, bearing, etc. [5mm hex socket bolt heads.“xx” is 13. I chose to leave the bolts and grommets in the valve cover while removing it, although I removed the three rear-most ones while reinstalling. That’s because I wasn’t replacing the grommets, and so I didn’t want to disturb them any more than necessary. One thing not mentioned here is that as well as the 13 bolts, there is a small plate that needs removing at the back of the cover. The small plate had an engine code stamped on it, and also provided a support bracket for thin metal hose. It is held on by a 10mm bolt, which I managed to round with a 10mm box head wrench for some reason I don’t really understand. I had to get it off using a bolt-out tool. Just thought I’d mention it in case anyone else has problems with that innocuous looking little bolt…]

3. The cam cover can be removed without removing the fuel rail hoses with just the right amount of twisting, lifting and turning. Be patient and work it out slowly. [I found the valve cover gasket stayed mostly in place when removing the cover, so I left it as undisturbed as possible to minimise the chance of oil leaks since I wasn’t replacing the gasket.]

4. Once the cam cover is removed, place some paper towels or clean rags into the spark plug holes. (See 2nd picture above) You don't want a washer or bolt falling into the cylinder, do you? [I plugged the holes with paper towel before taking the cover off, as soon as I had the spark plugs out.]

5. Remove the two bolts that hold the "J-tube" onto the tensioner and head. [6mm hex socket head bolts.] There are four small copper "crush" washers that form a seal for the oil that feeds the tensioner, two on top of the J-tube and two on bottom. Carefully remove these after removing the bolts. Remove the J-tube and then remove the bottom two crush washers. The bottom washers may stick to the J-tube if you are lucky, saving you the experience of trying to fish a small, thin, oil covered washer out of your head.

6. Carefully press down on the chain with your hand and compress the tensioner. [Actually, compressing the tensioner takes a lot of pressure – I used a rag to cushion my hand against the timing chain.] As the tensioner is compressed, insert a very small allen wrench into the hole in the metal tensioner tab and above the plastic ramp. [There are actually two small holes, on the same side of the tensioner as the J-tube. A small allen wrench or similar in one of them is sufficient to keep the tensioner compressed.] This will hold the tensioner in the compressed position for removal.

7. Remove the two bolts that hold the tensioner to the head. [5mm hex socket head bolts.] Once these bolts are removed the entire tensioner assembly can be removed. [To replace the top plastic guide, you need to release the tensioner from it’s compressed position, since the plastic guide is pressing up on the allen key. I used a big G-clamp and a couple of pieces of scrap wood to cushion the clamp against the plastic guides to manage the compression and release of the tensioner while off the car. The old top plastic guide just slides off sideways from the tensioner. Slide the new one on. Compress it and lock it in place for reinstallation.]

8. Reverse the procedure to install, make sure you use new crush washers and preferably, new bolts as well. Torque the tensioner bolts to 7 ftlbs and the valve cover bolts to 7 ftlbs. [The tension for the J-tube bolts isn’t mentioned here (or anywhere else I could find), so I somewhat arbitrarily chose 7 ftlbs. However, be aware that the the J-tube bolts are hollow, and the bolt side holes need to be aligned in the direction of the J-tube to allow oil flow through each bolt. So I marked the bolts heads with a marking pen to show the position of the holes, so they could be aligned to the J-tube. Once I reached 7 ftlbs on the torque wrench, I just kept turning until they were aligned -- so in fact they are torqued a little over 7ftlbs.]

[Mark944na86]

Any additional comments or corrections welcome. In particular, if anyone knows the proper torque setting for the J-tube bolts, I'll include that. I assume this is all the same for 16V 944S head, but I'm speculating. Any differences with the 944S could be usefully added as well.

[djnolan]

Mark,

Nice writeup. Makes it much easier to visualize the procedure. One question, where did you get replacement crush washers? Metric sizes not readily available I have found.

[mallard ducks]

"be aware that the the J-tube bolts are hollow, and the bolt side holes need to be aligned in the direction of the J-tube to allow oil flow through each bolt"

yikes - I didn't pay any mind to this when I did mine a while back - I thought the ends (rounded parts)of the J-tube itself were hollow so that no matter the orientation of the bolts oil will flow?

[Mark944na86]

Originally Posted by mallard ducks

"be aware that the the J-tube bolts are hollow, and the bolt side holes need to be aligned in the direction of the J-tube to allow oil flow through each bolt"

yikes - I didn't pay any mind to this when I did mine a while back - I thought the ends (rounded parts)of the J-tube itself were hollow so that no matter the orientation of the bolts oil will flow?

I could be wrong, and I hope you're right... this actually didn't occur to me, and I didn't check that possibilty explicitly. It would certainly be a better design if that were the case, and might explain why I haven't seen the issue mentioned in the write-ups I've seen.

Anyone know for sure? I don't want to alarm people needlessly...

[Mark944na86]

Originally Posted by djnolan

Mark,

Nice writeup. Makes it much easier to visualize the procedure. One question, where did you get replacement crush washers? Metric sizes not readily available I have found.

I got them from Porsche: part # 900-123-050-30. The new crush washers are actually aluminium, the copper ones (part # N 013 807 4) have been superceded by these. They were less than $1 each.

[racer951y]

Yea you don't need to align the holes the tube is designed for the oil to flow though that would be the point of a banjo bolt. Although, it is not a bad idea just for that much less of a oil restriction. I changed the chain at the same time I just did mine 139,000 miles on the clock it was a good idea lot less slack between the cams now

[Mark944na86]

Originally Posted by racer951y

Yea you don't need to align the holes the tube is designed for the oil to flow though that would be the point of a banjo bolt. Although, it is not a bad idea just for that much less of a oil restriction. I changed the chain at the same time I just did mine 139,000 miles on the clock it was a good idea lot less slack between the cams now

Thanks for clarifying that. I'll update the write-up.

Any thoughts on the proper torque setting for the J-tube bolts?

[KrazyKarl]

It's 7.5 ft-lbs according to the workshop manual, which is also the proper torque for the allen screws that secure the chain tensioner

[Mark944na86]

Originally Posted by KrazyKarl

It's 7.5 ft-lbs according to the workshop manual, which is also the proper torque for the allen screws that secure the chain tensioner

Thanks, I'll update with that info too.