Hi

I have a Shogun Mk2 2.8 reg 2000 turbo diesel fitted with the 4M40 engine with approx 108k miles on the clock. Recently it has occasionaly given a hissing noise when accelerating or changing gear. This was very intermittent and would happen and then stop and not do it again for many miles.

On a longish trip yesterday it was doing it fairly consistently as the turbo was beginning to operate, and I could turn it on or off by juggling the accelerator pressure around 2.5k revs.

As far as I can see the pressure relief valve at the end of the inlet manifold is opening - there was a slight oily wetness around the vent - hence the hiss.

I wonder if anyone else has experienced this problem. I think it's a faulty relief valve, but I don't know what would otherwise cause an excess of turbo pressure under light acceleration.

My inclination is simply to replace the valve, but if anyone is clued up on turbo troubles and has any other ideas, I would welcome the input.

thanks in advance

Rod Corderey