[MatthewL]

I’m a bit baffled. I’ve got what sounds like an exhaust leak on my 420 tourer. Running up to 3000 revs if on more than the lightest throttle with the engine under any load there’s a tsst-tsst-tsst that then peters out over 3000 revs.

I’ve put on a marigold glove and tried to cap the tailpipe to see if there’s evidence of a leak. Massive pressure builds, making a leak seem unlikely. I’ve been under the bonnet and under car around the joints with a bit of paper looking for it deflecting to identify a leak. Nothing.

So has anyone got an idea of where this engine noise could come from? It’s driving me mad!

Matthew

[itcaptainslow]

If it’s a T-Series, it’s likely to be from the exhaust manifold - I remember my 620ti having an appetite for the manifold to head gaskets.

[220 GSi turbo]

If it’s a T-Series, it’s likely to be from the exhaust manifold - I remember my 620ti having an appetite for the manifold to head gaskets.

I second that!

Both my 420 GSi Turbo (1997-2004) and my current 220 GSi Turbo had the manifold gasket blow in exactly the same place: at the timing belt end of the engine. I didn't deal with it straight away on the 420 and ended up needing a new (plastic) timing belt housing, as the heat from the 'jet' of hot exhaust gases had melted it! Obviously, if left much longer, this could have had a catastrophic effect on the belt

[MatthewL]

Thanks for the pointers. I’ll have another look at the manifold. I couldn’t sense a leak when I looked but I don’t suppose it has to be a big to make a fair noise.