Cams won't turn - HELP!

[K Simmonds]

But did they start life on that head? I've seen customers caught out by being sold a head with mismatch caps on more than one occasion.

As I said whip the plugs out and gradually loosen each cap right off one at a time, check for movement, re-torque and so on.

What a complete ball ache!!!!

[volcano rs]

have you changed starter motor at all ? i had a problem with v6 one just kept locking the engine .

[K Simmonds]

have you changed starter motor at all ? i had a problem with v6 one just kept locking the engine .

That's a good suggestion, remove the starter and see if the engine turns freely.

[newsh]

The head came from an AAN engine I bought. There were some bent valves due to the cam belt breaking. To my knowledge the head had not been touched since the belt went, I removed the head from the block the day Jannis came to pick it up and he took it away, cams and all.

[hunker7]

engine without head can be turned over by hand, and if caps are not torqued cams turn and move along with the engine.

[K Simmonds]

If it had bent valves the relevant guides should be replaced as they will be distorted, BTDT.

If turns with them backed off then that points to a distorted cap, which can happen with belt failure, though rarely, again BTDT.

[twoqu]

Seem to recaal there is a potential problem with caps that read the same upside down, so No 8 might be installed incorrectly. Loosen that one up or at least double check its the right way round. Perhaps a pic of the head with caps might help someone spot something amiss!

[hunker7]

I have a spare set of caps from my old head, can try using them I guess. Personally I'm suspecting intake cam because if I torque exhaust to 15nm, and leave intake loose it turns over. So i will use intake caps from my old head, all of them and see how it goes.

[hunker7]

Seem to recaal there is a potential problem with caps that read the same upside down, so No 8 might be installed incorrectly. Loosen that one up or at least double check its the right way round. Perhaps a pic of the head with caps might help someone spot something amiss!

Checked that. Made sure PN and Audi logo on the caps are on the same side as other caps if it makes sense.

[twoqu]

The caps have recesses that should all point toward the inlet manifold side.

[hunker7]

I'll keep that in mind tomorrow when I put it together. Thanks

[K Simmonds]

Right so you've narrowed it down it the inlet cam and it's always the inlet valves that cop it in case of belt failure.

By rights it needed new inlet guides and stems seals to be fitted before being reassembled with new valves, I would have done this as a matter of course. Having just finished stripping Charlies RS2 head from his crashed car I can see why!

Cam caps are not interchangeable from head to head as they are line bored like main bearings in the bottom end and the tolerances are extremely fine.

See which one is pinching and I guess you could just risk swapping that one but it's far good practice, I'd do it if I was stuck in the middle of Africa maybe but otherwise I wouldn't risk it.

As the cam shaft heats up and expands it could easily crack the non original cap or even shatter the shaft itself, I've seen this happen after explicitly warning someone not to do it, that event wrote the head off completely.

[hunker7]

Right so you've narrowed it down it the inlet cam and it's always the inlet valves that cop it in case of belt failure.

By rights it needed new inlet guides and stems seals to be fitted before being reassembled with new valve, I would have done this as a matter of course. Having just finished stripping Charlies RS2 head I can see why!

Cam caps are not interchangeable from head to head as they are line bored like main bearings in the bottom end.

I also left exhaust torqued to 15nm, and torqued up inlet 1 cap at the time, it still turned over with 3 caps torqued to 15nm, but as soon as I torqued 4th cap, regardless of which one it stopped and became very heavy to turn.

So there is no way I can just use old caps, it just won't work?

[K Simmonds]

So there is no way I can just use old caps, it just won't work?

It's very, very risky! If it's just one cap you might be okay there again you may not.

The caps need to be replaced with a new ones and the inlet side line board/honed to be 100% safe.

[hunker7]

If it exploded it might actually persuade me to get rid of it to make my life easier. Anyways, I'll start again tomorrow and see if I can find a problem.