I had a eureka moment today while installing an oil cooler...

Rewind to the my last race... I noticed that fast transitions from WOT to braking would cause the brake pedal to feel rock hard, and it would take a second before the brakes would start to work. It caused a few slight pucker moments, but nothing serious. When I checked over the brakes everything appeared to be good, so I just got used to the hesitation and figured I'd investigate more later.

Well today, as I was staring at the engine bay waiting for the oil to warm up after installing the new oil cooler I noticed that the previous owner had installed a "T" into the brake booster vacuum line for the boost gauge

and then it hit me! I've read (on this site) that its common for the V8 guys to replace the vacuum line going to the brake booster, not realizing it has a hidden check valve inside... The previous owner must have made the same mistake when installing the "T"! Its a perfect explanation for why the brakes felt rock hard; the booster was seeing positive pressure instead of vacuum! So I yanked off the line and sure enough; no check valve.

It made my day

 

I love it when a problem ends up so simple when expecting something worse!

 

where is this check valve? Is it in the little "s" shaped hose after the steel line?

 

Should be between the booster and the hardline. Right where it says check valve or something like that, written on the hose.

 

Yup, you can also usually see a little bulge, if ya know what I mean.

As much as I've torn my car apart, it survived unknown to me up until about a year ago. That reminds me, those two hoses are 20 years old :thumbsdown:

 

Whoops, sorry about that Will I had no idea there was a check valve in there lol. At least you figured it out and its a simple fix.

 

I'll have to get a new hose then... Well that was stupid

 

No worries, I would have made the same mistake myself

BTW, the car is kicking ***. I couldn't be happier with it.


Haha, glad I could help someone else avoid the same problem.