Should the VVT mechanism move?

[Van Black]

Hi all,

I'm currently rebuilding my engine, no savings made on parts.
Question is: should the VVT mechanism on the exhaust cam shaft be movable by hand?
I tried to see how it moves by holding on the cam shaft and moving the sprocket, it has very little play, probably 1/8 of tooth or less, but
other that that it's stiff as balls.

Seeing as oil pressure is what regulates it and that's about 4 bar max on a hot engine I would expect it to be movable.

Also, has anyone ever counted the chain links between the 2 sprockets? I've marked and noted them while disassembling the engine but I want to double check.

10x

[aluthman]

That's all the play it's supposed to have.

[mr larry]

Hi all,

I'm currently rebuilding my engine, no savings made on parts.
Question is: should the VVT mechanism on the exhaust cam shaft be movable by hand?
I tried to see how it moves by holding on the cam shaft and moving the sprocket, it has very little play, probably 1/8 of tooth or less, but
other that that it's stiff as balls.

Seeing as oil pressure is what regulates it and that's about 4 bar max on a hot engine I would expect it to be movable.

Also, has anyone ever counted the chain links between the 2 sprockets? I've marked and noted them while disassembling the engine but I want to double check.

10x

http://workshop-manuals.com/audi/a4_...ce_and_repair/

See above. No need to count the number of links, just need to get the adjuster onto the exhaust cam with the alignment pin in its hole (with the chain around the intake cam HPFP lobe). Then, while maintaining this alignment, slide the adjuster back so you can slip the chain over the intake cam sprocket. Next, use the intake cam tool to turn the intake cam towards the exhaust cam in order to get enough slack in the chain so that the adjuster slides into the exhaust cam and the adjuster alignment pin into its hole. If this succeeds, it's timed correctly. If the timing is not correct between the two cams then the adjuster alignment pin will not go into the hole. If i remember correctly though there were something like 21-22 links between the cam sprocket tops.

[rongeur]

As far as the VVT (Rear Exhaust Cam Adjuster) goes, a slight amount of play is fine. The solenoid valve (205) opens to let the oil pressure internally to free the internal variating adjusting mechanism. If you take it apart, there is a spring loaded pin that the oil pressure pushed to free the internal machined part to slightly change the entire exhaust camshaft timing.

On a distantly related note. Check this out. http://www.freevalve.com/

This is for the S4 but the A4 adjuster is very similar. https://youtu.be/z3EagRJN8sc