Questionable Dorman master bench bleeding method
Questionable Dorman master bench bleeding method Has anyone bled like this without issues? This just seems like a way to save money and screw the customer.. Thank you for your input.
BRAKE MASTER CYLINDER BENCH BLEEDING INSTRUCTIONS
1. Secure the master cylinder in a vise by firmly clamping the mounting flange on the casting. DO NOT CLAMP THE BORE AREA OF THE
CYLINDER! DISTORTION OF THE BORE CASTING WILL OCCUR!
2. If the outlet ports have non-threaded protective caps installed, replace with the provided threaded solid bleeder plugs. Tighten bleeder plugs by
hand to seat. Note: The plugs must be tightened enough to keep air from entering the master cylinder through the ports, but over tightening will
result in stripping the plastic threads and rendering them useless.
BRAKE MASTER CYLINDER BENCH BLEEDING INSTRUCTIONS
1. Secure the master cylinder in a vise by firmly clamping the mounting flange on the casting. DO NOT CLAMP THE BORE AREA OF THE
CYLINDER! DISTORTION OF THE BORE CASTING WILL OCCUR!
2. If the outlet ports have non-threaded protective caps installed, replace with the provided threaded solid bleeder plugs. Tighten bleeder plugs by
hand to seat. Note: The plugs must be tightened enough to keep air from entering the master cylinder through the ports, but over tightening will
result in stripping the plastic threads and rendering them useless.
yes, it's what i did when i replaced the master on my truck. takes about a minute. not really much else to do, the master cylinder is not complicated- just a cylinder with a plunger and two holes in it for front/rear. all you are doing is purging air. not sure what you mean by screw the customer, maybe if they recommended you buy something else in order to bench bleed.
big thing not to do is clamp the piece in a vice around the main cylinder part, because like it says if you distort it slightly the plunger inside will not seal and you'll have a weak master cylinder with internal leakage.
big thing not to do is clamp the piece in a vice around the main cylinder part, because like it says if you distort it slightly the plunger inside will not seal and you'll have a weak master cylinder with internal leakage.
TECH Enthusiast
Joined: Nov 2011
Posts: 609
Likes: 6
From: jacksonville,fl
I do have a little recent bad info about doing it that way. Some one on another forum, who like myself has done numerous brake repairs , did this method for the first time. He ended up with a soft brake pedal. The new method being the only variable to his experience, he purchased fittings & hose to bench bleed, which showed nonstop air bubbles from rear portion-- DEFECTIVE MC. Had it been bench bled the old way the first go around, less time would have been wasted trying to diagnose a problem that just turned out to be a defective mc with an internal leak.
The new method is supposedly to eliminate some amateur mistakes,but in my experience, you can't foolproof anything anyways & time honored methods have their good points.Personally, I'll stick to the old method, I have spare fittings & hose from previous jobs.
The new method is supposedly to eliminate some amateur mistakes,but in my experience, you can't foolproof anything anyways & time honored methods have their good points.Personally, I'll stick to the old method, I have spare fittings & hose from previous jobs.
yeah I already have a bad feeling about this. The instructions say to push in the piston 1 inch and i can barely get a half inch in. Can I just connected it to the booster like this and try pumping it without connecting the lines?
simply remember the goal is to get the air out of the master cylinder, how you go about doing it really doesn't matter as long as you don't break nothing and make as little of a mess as possible.
what i did on mine is put the plugs in the outlet ports to block them, then stroked the plunger fully and released it slowly. maybe about 10 strokes and you're 90% there. then remove 1 outlet plug and slowly stroke to squirt fluid, when you bottom out the plunger you need to get your finger over the outlet to prevent it from sucking air or get the plug back in just shy of bottom out the plunger while fluid is still squirting. then release the plunger slowly. couple times each port and there will be no air in there. with both plugs in you should not be able to depress the plunger more than 1/4" because it will hydraulic lock. the hard part is setting up the master on the bench so when it squirts it goes into a container and doesn't make a mess everywhere. be careful to stroke slowly because it will shoot fluid far. wear eye protection.
what i did on mine is put the plugs in the outlet ports to block them, then stroked the plunger fully and released it slowly. maybe about 10 strokes and you're 90% there. then remove 1 outlet plug and slowly stroke to squirt fluid, when you bottom out the plunger you need to get your finger over the outlet to prevent it from sucking air or get the plug back in just shy of bottom out the plunger while fluid is still squirting. then release the plunger slowly. couple times each port and there will be no air in there. with both plugs in you should not be able to depress the plunger more than 1/4" because it will hydraulic lock. the hard part is setting up the master on the bench so when it squirts it goes into a container and doesn't make a mess everywhere. be careful to stroke slowly because it will shoot fluid far. wear eye protection.
i bolted to master to the booster. then if you ak any parts store they will have a 5 dollar bench bleed kit which is two pastic fittings that screw ino the master with 1/8th inch lines you run directly back into he resivor. fi the resivor and pump the brakes..that smple
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i bolted to master to the booster. then if you ask any parts store they will have a 5 dollar bench bleed kit which is two pastic fittings that screw ino the master with 1/8th inch lines you run directly back into the resivor. fill the resivor and pump the brakes..that smple
I've done it both way, with the solid plugs and with the plugs+ line going back to the reservoir. Got a firm pedal both times.
I've seen people say not to bolt it into your car and bleed it with the booster but I can't remember why. Regardless I always do it by hand and I dont even have a vise lol.
I've seen people say not to bolt it into your car and bleed it with the booster but I can't remember why. Regardless I always do it by hand and I dont even have a vise lol.
