Stuck Variocam

Hi Guys, Just got the bad news from the garage. I have a stuck variocam on one side of the engine which results in a lumpy idle, but after 3000 revs the car runs fine. My question is should it cost £1300 plus vat. P.S. i'm not questioning the specialist but realy trying to find out what the variocam does if there is a cheaper alternative. Many thanks Matt

Depends what it actually is, and what model you have (3.4 or 3.6) as to what's involved. If you have a 3.4 and the solenoid valve itself has gone, then it is a £600 part, plus quite a lot of work to change it. If it is only the solenoid coil, then it is a much cheaper part (£115) and simpler job. If the valve needs changing, then it would be logical to change the coil at the same time, so £1300 doesn't seem too unreasonable. I believe that it can be done without removing the engine. The Variocam solenoid changes the camshaft timing, which if it fails causes incorrect timing and a lumpy idle. On the 3.6 there are two actuators - one changes the cam timing, and the other changes the valve lift.

Thanks Richard, perfectly happy with the garage. They seemed really professional and they mentioned the solenoid valve for the 3.4lt. Thanks for the confirmation on price - I just was not sure as this is it's first trip hopefully the last to be repared. Would this issue be caused by very short runs in the car? I drive it 3 miles to the station and 3 miles back most days and only once or twice a month on longer journeys. If this is the case I might have to get a bus instead!

Unlikely to be caused by short runs, so no need to get a bus pass. It is usually the coil which fails, rather than the valve itself. I guess they have checked the coil in some way to have diagnosed the valve as being the problem. It might be worth confirming exactly what they plan on doing.

FWIW Porsche Aberdeen just quoted me £1500 for this job inc. VAT. Richard, what is the difference between the variocam solenoid coil and valve, please? When I last had this job done on the Boxster at Ninemeister the mechanic showed me a wire with a sewing thread drum type lump of rubber on the end. I presume this was a coil?

Here is the valve and coli from a 3.4 engine. The coil is on the outside, and the valve on the inside.

VarioCam Plus, on the 3.6 engines is quite different. Valve timing is changed by vanes within the camshaft sprocket. Valve lift is controlled by the tappet buckets themselves, operating on different lobes on the cam. Lift and timing have an actuator for each function (40 & 41) which control the supply of oil to the vanes (for timing advance) and to the tappet buckets, to switch the the lift from low to high.. These actuators can be changed much more easily.

This shows how VC+ works:

Here is the 3.4 Variocam valve, which acts on the timing chain to effect the valve timing change.

Thanks for that Richard: so 5 is the valve is it? And 2 the coil? That would account for the difference in the cost of the job. Replacing 5 is a cams out job I guess?

Yes, 5 is the valve, and 2 is the coil. The cams don't have to come out, but the covers have to be removed, and there are special tools to hold the cams in place.