Don't buy NAPA brake master cylinders

[Diesel]

So I am back to figuring out why my pedal won't return quick. Tested my vacuum pump and it's making over 70in of vacuum. Figure it's the master...buy a new napa master...made in china (I would normally leave it at the store but oddly I took it home this time)...go to bench bleed it and the chinese casting leaks through the threads! An OVAL hole was threaded on this thing! RETURNED. Like a human patient, my truck is so American it just rejected that chinese organ. Found a made in USA master on eBay Hopefully I don't need a booster but I have good assist so I doubt i do. My vac seemed unusually high but I don't know.

[bmoeller]

If you don't replace both parts (booster and m/c), that can sometimes void warranty. Or, in my case, the other that wasn't replaced, dies within a month.

Vac pump should max out at ~25-26".

[Diesel]

I was confused why I had so much vac? It seems high but the gauge pegged at 70. It could be higher. The gauge I borrowed was likely harbor freight or something equally junk but I doubt that would cause an improper reading. It's almost impossible for a vane pump to pull more vacuum. Maybe I'll try it again?

[BobS]

So I am back to figuring out why my pedal won't return quick. Tested my vacuum pump and it's making over 70in of vacuum.

Get a new vacuum gauge! The maximum
achievable vacuum at sea level is
approximately 30" of mercury, which
is equal to the weight of a column of
air sitting over any one spot on an
average day.

REF: http://www.uvm.edu/~pmrc/vacsap.pdf [and many others if you google maximum vacuum on earth]

[Diesel]

Lol! I didn't know that but the gauge must be junk then. Is there any special procedure for using a vac gauge? I just removed the vac line from the booster and then used a couple adapters to make a cone shaped adapter fit inside the hose so it would reduce down to the same size as the hose that goes to the gauge.

[Tacoclaw]

It's probably not registered in " of HG. I doubt it is since, like BobS said 30" is just about the highest achievable reading you can get, it doesn't make much sense to have the gauge marked that high. It may be " of H2O or something else.

[Diesel]

Well I'm an OFFICIAL IDIOT...just looked again and I was reading cm not inches! Yeah so it's running about 28" of vacuum. Thank you bobs for pointing that out!

[Diesel]

Anyway I am hoping that since I have good vacuum and the pedal isn't hard that the new booster is OK (installed last year) and the reman a1 Cardone master cylinder is causing my pedal to not return.

[PToombs]

We can always use an extra Official around here! Some of the gauges I use at work I have to double check too. Why would you have Bar on the outside and PSI on the inner scale if it's made and used in the USA?

[Diesel]

By the way guys. There is still another nos bendix made in the USA left on eBay. Not sure of they are any good yet but it might be worth someone picking it up just to keep it on the shelf.

[hp383]

Well I'm an OFFICIAL IDIOT...just looked again and I was reading cm not inches! Yeah so it's running about 28" of vacuum. Thank you bobs for pointing that out!

I think I have the same gauge I too was wondering how I was getting 70". It took a day or two, but when I looked at the gauge again it was right there...

[Diesel]

So far so good. The NEW bendix made in USA master fixed my brakes. No longer is my pedal slow to return. Like I said there is another one on ebay and if youre smart you'd get that instead of the chinese ones out there today.