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tucsonjwt · 01-29-2013, 03:46 PM

I just replaced the mc on my 83 C20. A local brake shop used a Raybestos MC as a replacement a couple years ago and after my truck sat for 2 months waiting for a dump hoist rebuild, I very little braking power. So, I discovered a leak around the top cover and replaced the gasket under it with one from NAPA (about $6). After a lot of fiddling with it I got the leak to stop, but there was a lot of rust on the cover and around the top edge of the mc (and this is in AZ.)

So, I bought a new AC Delco MC online (lots of places to get Delco for cheap online.) I had my mechanic replace the master cylinder and he said there was a lot of air in the lines. Braking is AOK now.

Bottom line, the gasket under the cover can be replaced, but you should probably check to make sure there is no rust in the cylinder and drain/refill the fluid.

Don't buy a Raybestos MC.

01-29-2013, 03:46 PM	#5
tucsonjwt Registered User Join Date: Jul 2007 Location: Tucson, AZ Posts: 3,198	Re: Master Cylinder mc replacement I just replaced the mc on my 83 C20. A local brake shop used a Raybestos MC as a replacement a couple years ago and after my truck sat for 2 months waiting for a dump hoist rebuild, I very little braking power. So, I discovered a leak around the top cover and replaced the gasket under it with one from NAPA (about $6). After a lot of fiddling with it I got the leak to stop, but there was a lot of rust on the cover and around the top edge of the mc (and this is in AZ.) So, I bought a new AC Delco MC online (lots of places to get Delco for cheap online.) I had my mechanic replace the master cylinder and he said there was a lot of air in the lines. Braking is AOK now. Bottom line, the gasket under the cover can be replaced, but you should probably check to make sure there is no rust in the cylinder and drain/refill the fluid. Don't buy a Raybestos MC.