too much boost

[silvertdvw]

I have an 86 turbo diesel jetta with a k24 turbo and I have it set at 12 psi. This morning I took the car out and for the first full boost run of the day the boost kept climbing untill I let off at 20psi. this has happened once before and it was also the first full boost run of the day. does anyone know whats happening?

[vanbcguy]

Sounds like your wategate is sticking... Guessing your factory BOV is disabled already as you'd be hitting that at around 12 PSI anyhow.

I think generally the cause is a lot of carbon guck getting in around the wastegate valve.  Fix is to clean it out, but that would require pulling the turbo unless you're really good at working in really really tight spaces.