Blue smoke after startup

[SteveH]

I have a slightly puzzling problem with oil burning on my S2.
It started a couple of weeks after having the head off to be re-conditioned and adding a newly re-conned RS2 turbo (turbo dynamics)

On starting the car each day from cold, the engine fires up straight away and sits there idling without any problems. For the first minute to minute and a half there is no blue smoke at all. I can rev it and this also produces no smoke. Approximately 2 minutes after the car has been idling a load of blue smoke comes out of the exhaust. This lasts for about 2 minutes and then mysteriously disappears. This is the only time it produces any smoke. I can drive the car hard - no smoke, give it major overrun -no smoke and rev it to the redline and it still seems to be oil free.

I'm thinking it must be a seal of some sort - either valve stem or turbo that's leaking while it's expanding during the warm-up, however, I'm damned if I can think of a way of testing to find out what it is.

Any ideas or similar experiences would be appreciated. I'd send the turbo back to be checked, but I'm sure the company will tell me it's either OK or I've done something wrong

Cheers
Steve.

[Vagsport]

I'd say the fault lay in the turbo or associated breather system. When I first ran my car on a K26 (meant to be RS2) I had the same problem. It turned out the turbo was a K26, BUT NOT RS2 spec, more like a 10V (MB). The vacunm requirements are different for both turbos, the 10V runs more vacunm @ idle. I had to fit a restrictor in the breather system, to increase vacunm in the engine on idle. You can check how much vacunm you have by removing the oil filler cap during idle. If there is no suction, you've found the culprit. Fitting the restrictor, you will find some resistance when trying to remove the oil filler cap during idle, and it should'nt smoke after that. Shame you're so far away, I could have rigged it up for you, takes about 5 mins.

[Mihnea]

Now one thing is sure 100%, the turbo IS a real RS2. But maybe this has to do with the ADU engine having different vacuum at idle compared to the 3B?

[Graham]

2 Minutes? how long would it take oil too leak from the turbo through the air system, as it has got quite a distance to go

[SteveH]

Thanks chaps,

I've tested the pull on the oil filler cap and it's just about there, however, there's far less vacuum effect than on my old KV engined coupé. I suppose I could test this theory by temporarily removing the crank breather hose, would this help to prove it's due to the crank breather/pressure?

Cheers
Steve.

[Vagsport]

As I thought, it is a vacumn related / breathing problem. I will dig out details for the breather kit I used on mine, cost about £25 inc. delivery.

[SteveH]

Thanks m8,

Details would be greatly appreciated

cheers