I'm an online writer and proud owner of an Audi 1.8T. My articles focus on helping Audi owners handle DIY projects.
Cam Chain Tensioner and Half Moon Gasket DIY
After a pressure test, I realized that air was blowing out of the right side of my engine near the cam chain tensioner. When I unhooked the SAI to Combi crinkle hose so I could get my finger in and under, I could feel the air blowing out and rubbed off a nice coat of fresh oil from the half moon cut in the head. Why VW/Audi decided to make a big hole in the head then fill it with a piece of rubber I have no idea, but at least now I know how to fix the leak.
This job is easy, very easy, especially if you are only changing the valve cover gasket so you can pull off the valve cover to give it a good polish. But, if your VC (valve cover) is leaking, it is recommended to change your cam chain tensioner at the same time as it is more than likely nearing the end of its life span as well.
As I said this job is easy, easy in the steps and tools you need to do to get it done. But when it comes to actually changing the cam tensioner gasket, it is a huge pain in the a**. Also, you will be working around your timing chain, so the last thing you want to do is have the chain move out of place and screw up your timing.
This DIY article will cover replacing both gaskets, I am a little short on pics for the cam tensioner side as I was more concerned with getting it in right than I was with pics, but I have found a few pics on the world wide web that should help.
The VC is simple, but do the cam chain tensioner gasket at your own risk as I will not be responsible if you happen to mess up your engine.
Tools and Gaskets Needed for the 1.8T
The only specialty tool that is needed for this job is a cam tensioner tool (which is only needed if you are doing the tensioner gasket and half moon seal) the tool is VW tool # 3366. It can be bought on eBay for 12-15 dollars. It is basically a long 6mm bolt with a plastic "T" on the top to loosen the chain from the tensioner.
- 10mm Socket (Preferably Deep socket for the back VC bolts)
- Socket wrench
- Valve Cover Gasket 058-198-025
- Cam Gasket 058-198-217
- Size 30 torx bit for cam tensioner bolts
- High-temperature silicone gasket sealant (optional)
- 5mm Allen wrench for Vac box on VC and cam tool
Basically, if you are only doing the valve cover gasket, you will only need a 10mm socket and a 5mm Allen head wrench if you still have the vac box over coil 4.
Pulling That Valve Cover Off!!
- First, if you have a vacuum box over your fourth coil, you will need to remove it and the bracket that it sits on. I haven't had one for years but I know it is a combination of 10mm bolts and a few 5mm Allen head bolts.
- Once that vac box is off, unclip the wire harnesses from the coils. Directions for that can be found at Changing coils DIY (if you don't know how to pull them off).
- If you want you can label your coils 1,2,3,4 with a permanent marker if you wish to put them back in the same order during re-installation, but really it doesn't matter. Also while you have them all out you might as well change your spark plugs, 15lb of torque.
- On the left side of the VC there are two clips that hold the plastic timing belt cover on (location is circled in blue in the picture), just release both metal clips and pull the plastic back a bit. There is no reason to fully pull it out.
- There are 9 bolts holding the valve cover to the head they are all 10mm bolts connected to studs. Three in the front, three in the middle and three in the back. I don't know if every car is the same, but the corner-back studs on my VC were really long. That's where a deep socket will come in handy, also so you can torque them to the right specs during re-installation. If you start unscrewing a bolt and the whole stud unscrews with it don't worry. Once it's out you can grip it with vise-grips remove the nut and replace it with a 10mm nut from a hardware store. If you polish your VC just buy all new 10mm nuts so they shine like the cover. In the picture, the green circles indicate where all the 10mm bolts are.
- The wire harness is clipped onto the VC with plastic clips. They can be removed by wedging a flathead screwdriver between them and the valve cover. Doing so will make them pop out, (circled in orange). Also, the ground bolt from the wire harness (circled in green) will also need to be removed.
- When you try to pull up on the VC you will notice that the right corner won't come up. That is because VW ran a metal hardline right above that corner. The hardline connects to a hose that runs to the turbo inlet pipe. Now you can pull off that hose, which I would recommend or you can leave it on for this. Either way, you need to bend this bit*h back some. Don't get all He-Man on it just bend it a little and see if the VC will slide off, if not repeat till you can get it off.
- If you're only changing the VC gasket, you can now pull the old one off (don't forget the one around the spark plug seal) clean off the surface, lay down some high temperature silicone sealant on the bottom side if you want, wait five to ten minutes for the sealant to skin over and push on your new gasket, followed by the valve cover.
- Tighten the bolts down to 7lbs of pressure and let it sit for 24 hours (if you used sealant) to dry.
Are You Sure You Want to Change the Cam Tensioner Gasket and Seal?
This is simple in words but a pain in the butt to do. You will also be working near the timing chain and loosening the tensioner to access the gasket and half moon seal, so work at your own risk. I don't have a lot of pictures of placing in the half moon seal, but I can tell you it is a very tight fit with very little room to work in. But all said and done, it should be pretty simple and straight forward as long as you don't move the timing chain. I didn't try to move it but it doesn't seem like it would move that easy anyway.
- The item circled in green in the picture is the tool (VW tool #3366) that relieves the tension from the chain, it is a little hole right next to one of the bolts circled in red that you will be removing. Once you look at that area it will be obvious where the tool goes. With your 5mm Allen wrench start tightening down the tool till there is some slack in the chain.
- Once you have some slack in the chain you can start unscrewing the four bolts circled in red. they require a size 30 torx bit. fully remove them and the tensioner is now free from the head.
- With your fingers or a small flat head screwdriver, you can push out the half moon seal and peel off the gasket under the tensioner. If this is the first time it is being done they both should come off pretty easy as the moon seal shrinks with time and the gasket has no silicone sealant on it coming from VW.
- The photo is not mine and borrowed from a forum so don't for a minute think your tensioner will give you that much room to work. But it does give you a good idea of what it all looks like and how it all fits together. I believe to get it this high he took one of his cams out and later regretted it with a timing issue.
- With a towel and some brake/carb cleaner clean the area under the tensioner the best you can.
- I used gasket sealant when I put the seal and gasket back in, so that is up to you whether you use it and how much you use. I put some on the round part of the half moon and on the blue parts of the gasket and so far everything is holding strong.
- Once your seal and gasket are in position (have fun with that) you can bolt down the cam tensioner. The torque specs for the tensioner is 7 ft-lbs.
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.
© 2011 Writen4u
Marvin on March 20, 2019:
1st off thanks for the very informative article! I own a 03 A4 Quattro with the 1.8t and ran across this article while searching for more info on the topic and noticed your intake manifold!? Where did you get it and how can i get one
Writen4u (author) on July 22, 2015:
yuls-Depending how much you want to spend the first resource would be the dealership parts counter, besides for that mjm autohuas, ecstuning, germanautoparts, or any other online retailor you feel comfortable ordering from.
yuls on July 21, 2015:
hi just want to ask where can i buy a cam shaft chain tensioner....
Writen4u (author) on July 07, 2012:
Responding to your email. I have not yet moved to the mkv coils, once I do I will update my article. Most people have been happy with the change from what I've read. For now I need to finish motor mounts and bushings. DIY for polyurethane transmission mount under $50 will be up soon!.
zach on July 07, 2012:
hey man, i just wrote you an email regarding the spark plugs. but ya, another good write up on the valve cover. i made the mistake of using too much sealer and now im going to do it again using this DIY and my newly aquired bentley manual. thanks.