New master cylinder lacks a vent

[Chris P]

The new master cylinder for my M37 just arrived and its cover lacks an attachment point for the vent. Should I install it as is without a vent or should I try to use the cover off of the old one (assuming it fits on the new one)?

Is the new master cylinder different from the old on in some way such that the old one needs a vent but the new one does not?

Thanks

[RMS]

the cover will interchange. do not run the new cover. it is vented and with the placement of the mc being so low on the 37 you will suck in contaminants. swap the lids and make sure the vent line is clean and connected.

ignore everything i have written if the only time you use your brakes is to move the truck on and off a trailer

[ZGjethro]

When I bought my M37 three years ago, the brake lever went to the floor. I ended up replacing the MC with probably the same one you have, which had no vent. That was fine with me since I had no vent MC vent line to the intake horn on the truck. I made up a fitting for my pressure bleeder and ran a poly line from the MC location into the engine bay. After bleeding the brakes, I put a filter on the end of the hose, and I have filtered air entering the MC and I can easily re-bleed my brakes using the pressure bleeder. As a plus, when pressure bleeding I cannot pump brake fluid into the intake horn like you can on an original M37