Brake booster vacuum leak

[Genesiswonderer]

So I know this is a common problem on DH.

It started a couple years back where after the car sitting for a few hours the brake pedal would be hard on start up. Braking while the engine is running is fine.

It was always worse when it was cold outside.

However this seems to have worsened lately.

While it used to be a couple hours in the cold, now it seems to be as little as 30 minutes before all the vacuum leaks out.

I know this is a common problem on these DH cars.

My question is is it just the check valve or is it the booster itself?

Would love to hear from yall who have had this issue what the fix was for yall!

Any input is appreciated!

 

[joegr]

It could also be the vacuum hose itself. Get some locking pliers and squeeze the vacuum hose to the booster all the way closed while the engine is running or just after. Check the brake pedal after a few hours. If it still has one good press in it, it is almost certainly the check valve and or hose. If it does not, then it is likely the booster or hose.

 

[Glasman888]

So I know this is a common problem on DH.

It started a couple years back where after the car sitting for a few hours the brake pedal would be hard on start up. Braking while the engine is running is fine.

It was always worse when it was cold outside.

However this seems to have worsened lately.

While it used to be a couple hours in the cold, now it seems to be as little as 30 minutes before all the vacuum leaks out.

I know this is a common problem on these DH cars.

My question is is it just the check valve or is it the booster itself?

Would love to hear from yall who have had this issue what the fix was for yall!

Any input is appreciated!

The cold sensitivity points directly to the check valve. The rubber diaphragm inside it gets stiff when cold and stops sealing. It's the most common failure and a cheap, easy first fix. Swap that $15 part first.

If the new check valve doesn't solve it, then the leak is internal in the booster diaphragm. That means replacing the booster itself, which is bigger job. Most of us on the forums find it's just the valve. Start there.

 

[Genesiswonderer]

The cold sensitivity points directly to the check valve. The rubber diaphragm inside it gets stiff when cold and stops sealing. It's the most common failure and a cheap, easy first fix. Swap that $15 part first.

If the new check valve doesn't solve it, then the leak is internal in the booster diaphragm. That means replacing the booster itself, which is bigger job. Most of us on the forums find it's just the valve. Start there.

Thanks for the reply!

 

[lobsenza]

I had this issue. The dealer could not find it. I eventually found it was pressure on the vacuum house going to the brake booster as it passes through the opening going to the brake booster. I reversed the direction of the hose clamp and the problem was resolved.