Evo VI – Boost Leak Check

(First posted on MLR forum in April 2014)

Thought it’d be a good plan to do a boost leak check. So I machined up a bung to fit in the turbo inlet that would allow me to connect the compressor via a tyre valve.

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using some washing liquid in water i put it everywhere to find the smaller leaks that couldn’t be heard. here’s one


another. the hose clamp just wasn’t clamping tight enough.


throttle body off as i could hear a leak on it



leaky o-ring replaced


retest after the fixes including new hose clamp, new line to the boost gauge and new o-rings in the throttle body. no leaks


looked into changing the dump valve as it always vented too early so let out even very low amounts of boost when it needn’t have. then i had a new plan. modify mine to allow adjustment of the pre-tension on the spring. that way i can adjust it to change the pressure that it needs to fully open. i just drilled and tapped the back plate to allow fitting a bolt. this is just the same as the adjustment on the later versions. works well after some gradual adjustment over a few days journeys, slowly increasing the pre-tension to the point i’m happy with.



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