Fluctuating MP on rear engine

[kevin]

Ken,

I have had the surging you are talking about in my '73 P, but 4" seems a bit excessive. 2" surges have turned out to be the wastegate, as the other gentlemen suggested. Just lubricate it.

But I have also had problems like this (once) indicate a failure of the turbo. So I would have your mechanic check that as well, make sure the blades are still intact, will spin freely, etc.

Since you have a turbo, not a P, RPM is not likely to be a factory, your turbocharger is not working nearly as hard as the P model's do.

I am sure mechanics on the board can suggest other possibilities, I am just reporting to things that have happened to me as an owner.

Kevin