It’s been a long week - Camshaft hydraulic fingers

[Nobby]

Hi all

Long time no posting.

I’d been saving up the parts to do my cambelt, and managed to accumulate a number of others things to do at the same time. One of those thing was to replace some of the camshaft rocker fingers that transfer the movement of the cam (via these rocker holders) to the tops of the valves.

There’s one for each valve (obviously) and the inlet rockers have space for 3 hydraulic finger and the exhaust have 2. The holders are kept in place by long shafts. These would be impossible to remove with the engine in situ, so it’s either remove the heads or the whole engine.

I didn’t think the holder were the issue so decided to replace some of the fingers. The holders do have bearings in them though which could go bad but they look pretty beefy.

I’ve had my car for nearly 15 years now and although the mileage isn’t increasing much I’m keen to stay in top of maintenance. In recent years I’ve had a tick tick tick when cold from the O/S. It goes after a few minutes but always worries me. Multiple oil changes didn’t make a difference so I thought this cambelt change I’d change some* of the hydraulic fingers

The little hydraulic valves themselves are pretty basic. A small cylinder that slots into the holder. I believe they get oil
Pressure from below which keeps the tip nice and cushioned on the top of the valve.

They aren’t that hard to swap really it’s just getting to them. You need to prise them upwards with a small pick. I also used a plastic trim tool so you don’t scuff the head anywhere. You also need to remove the cams (which is tiresome and expensive when you need to replace all the 52 bolts) but if you are doing the cam tensioner pads with your cambelt it’s only a little extra effort. With the cams out you can rotate the holder in place and see rhe hydraulic fingers.

The parts in question are 16/24 for inlet and 16/25 for exhaust.

Exploded view

Now, the hydraulic fingers are expensive though. From Audi they are about £40. EACH! I doubt anyone wants to spend £1.6k on some. You can buy the holders instead which come with fingers. They are about £250 each. And you need 16 of them. So what to do. In my head I thought the exhaust valves would get more punishment from heat so I bought 16 and would clean all the others and find the best ones.

The ones I bought were from AUTODOC made by AJUSA. They don’t list against the RS6 but checking the OE part reference they are listed as a replacement. Inlet and exhaust are the same part.

AJUSA part

I started the work on Monday. And finished it today after 3 proper days of work and a break in the middle to avoid bad weather and order some gaskets which missed my original order.

New ones just slip straight in. Old ones had a bath in the ultrasonic cleaner then a poach in some warm oil overnight.

Clean vs old

I also cleaned all the caps very gently.

Cleaned vs dirty cam caps

I’d also decided to clean my injectors and replace all the seals. Little did I realise the pain it would cause me. When removing 2 injectors the plastic caps were nowhere to be seen. They could only be in one place though as they fit in the end which goes inside the inlet manifold.

One cap had broken up and needed hoovering out but one was too heavy and had to be hooked out. Luckily with the cams out the valves were closed.

Inspection camera helped

All parts accounted for thank god.

Phew!

All back together this morning. Took a while to prime the oil pressure. Started first time and sounds lovely and smooth.

I’ll give it a few days and change the oil but I’m pretty happy with that!

[TechNick]

Great work, as ever, Chris

[Shoppinit]

Beautiful job. Did it cure your ticking at cold? I have the same but I think I can live with it, especially after seeing that