Quote:
Originally Posted by TonyCy
It’s the existing mc with new seals fitted.
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When you fitted the new seals, did you use a cylinder hone to remove the ridge that forms at the normal end of piston travel? If you didn't, chances are you have damaged the new seals and need to replace or rebuild the MC .
Over years of operation, a wear ridge develops in the cylinder walls at the normal end of travel on the MC piston. If you do a brake bleed using the pedal pump process you need to put a block under the pedal to stop it from travelling beyond its normal range of operation (a bit of a guess as to where that is). If you repeatedly push the pedal right to the floor as part of the bleeding process without having reamed the cylinder you force the seal over the ridge eventually leading to seal damage and leakage back into the reservoir. Been there, done that - bought the new MC! That is the primary reason I now use a pressure bleeder when I do my semi regular brake fluid flushes on old cars.
I have used the hand vacuum pump on a car that I didn't have a correct master cylinder adapter cap for doing a pressure flush. That was a simple brake system flush replacing old fluid with new fluid and did not involve removing any air from the system. It probably took 20 - 30 minutes at each wheel for a single bleed port (not a Volvo) leaving me with an incredibly sore forearm at the finish. The rate of fluid flow with the hand pump was so slow that I don't think it would do a very good job of removing trapped air in the system.
To echo C1800, when you did the bleed 'by the book' did you use the Volvo service manual procedure and you got all 3 bleed ports on each front caliper? When I completely rebuilt my 142, I got lots of experience repeatedly bleeding the system as I repeatedly discovered new leaks at the various flare fittings in the system. With the pressure bleeder, on the 140 I never had to resort to elevating the rear of the car to complete the bleed process.