Stiff brake, hissing after master cylinder change

[itwonder]

Changed master cylinder. Now have stiff brake and hissing which must be a vacuum leak. Quick inspection; didn't see loose hose. Is there suppose to be a gasket between MC and booster? Didn't see one. No sure where it's leaking or how I might have goofed up the booster by changing MC. It's a brand new Dorman MC, which I noticed is made in China. Anybody had trouble with those? Will be digging into it today.

 

[Racer X]

You have a disconnected vacuum hose, which in turn is not allowing the brake booster to do it's job (it needs engine vacuum to function).

Find that hose, and you should be back in business.

 

[itwonder]

Pinched off booster vacuum line; hissing stopped and idle stabilized. So the vacuum leak is in the booster. Pulled MC away from booster and found MC gasket (o-ring with a rectangular profile) is missing. Shame on me; I didn't notice the new MC came without a gasket. But I'm not happy with Dorman for leaving it off. Now trying to figure out where to source one quickly. Not available from Ford. Hesitant to reuse the old one.

 

[luigisho]

I would contact the us dorman customer service and see if they can get you one. Quickly is crapshoot on any hard to find part. Push comes to shove, find the ford part number and track one down.

 

[itwonder]

Fixed. Reused the old seal. Was able to get seal on without disconnecting the lines, which was a huge time saver. I'll post what I learned about replacement master cylinders and seals later.