I recently found that the brake pedal is hard on cold starts. Sometimes i must double pump at first real brake down. Scary enough..

However, i found that the non return valve on the vacuum line was defective, so I renewed it.

Still problem persists. Had a real good check on the vacuum hoses, could not find any real leak, although they are starting to show signs of hose protection weardown on contact points (clamping points).

So, today I went out again to check one more time, but only to discover that the turbo whistle sound that usually kick in after a few minutes on idle, never did. Removed a few hoses, and yes there is at least some vacuum.

And yes, the non return valve is fitted the correct way.

And yes, the fuel consumption had gone up recently.

And no, there are no visual leaks in the brake servo area, brake fluid level is stable.

Of course, a bit fed up with this matter. Guys, are there any way to determine if the vacuum pressure is sufficient ? Where should i check, and how ? Do you know what is the correct vacuum ?

Perhaps I can start on the vacuum pump outlet and check pressure at every connection..?

Anything else to check ? Could it be on the intercooler side ?

And one last thing, there is a vacuum hose between air filter housing and one of the vacuum operated valves. What is this hose for, and should there be vacuum her ??

the hose to the air cleaner is a clean feed to the control valves    if you have a gauge and suitable pipe and a tee  you can tap in anywhere on the small bore stuff( not air filter line)  from memory it should be approx 17 inches or equivalent ---think that's water not mercury