weird master cilinder problem

[tjltd]

good point , i guess problem solved!!, thanks

[Blaze86Vic]

Ok, there is a lot of confusion and bad assumptions in this thread.

1: The front reservior (ie. the smaller one) is the reservior for the rear drum brakes. The one closer to the driver (ie. the larger one) is for the front disc brakes.

2: The squirting that the little reservior does is completely normal, that is why the cap is sealed between the two reservoirs.

3: Bench bleeding is done on the bench for a reason, the pedal does not fully extend the MC piston. You have to have it off the car and pushing on the piston with some kind of poker (usually a screw driver) to compress the piston all the way. This is why you bench bleed the MC, so that you get all the air out that you would normally not get with the pedal.

[Lincolnmania]

+2 :slug:

[tjltd]

don't know why i've always asumed the small reservoir was for the disks, thanks for correcting that situation guys, i'll start again on saturday when i get the day off, i guess all this confusion started with fluid leakage from the cap and the switch at the prop. valve, gonna replace the cap and gasket and plug the Prop. Valve and re-bleed all the sistem including the original MC i took off. Thanks to all who replied this thread for all your help.

[Archangel]

3: Bench bleeding is done on the bench for a reason, the pedal does not fully extend the MC piston. You have to have it off the car and pushing on the piston with some kind of poker (usually a screw driver) to compress the piston all the way. This is why you bench bleed the MC, so that you get all the air out that you would normally not get with the pedal.

Someone hasn't been reading the instructions that come with the new master cylinder - where exactly did you see written you have to bottom out the m/c pistons?

[Blaze86Vic]

Someone hasn't been reading the instructions that come with the new master cylinder - where exactly did you see written you have to bottom out the m/c pistons?

LMFAO?!!! You think that because you read the little half ass instructions that come from slave child sweat shop, you know how to install an MC? Do yourself a favor, don't work on your own brakes, they also don't tell you to check for rusty lines, and leaking joints.

Every shop in the world bench bleeds MCs because you can get ALL the air out of the MC by bench bleeding it. It's in shop manuals everywhere.

Here are some written instructions you can follow like a blind religion,
1: Don't leave air in your brake system.
2: Don't be a robot, make your own decisions.

[CheeseSteakJim]

ugh, this thread is about to head nowhere fast

[1987cp]

I've heard it claimed that it's actually possible to damage a master cylinder by failing to bench bleed it. That said, when I installed mine several years ago and didn't know to bench bleed it, I *seemed* to get all the air out of the system through regular bleeding and have basically had satisfactory braking performance since, so I've always assumed that the thing wasn't actually damaged by my improper procedure. However, I could easily see that bench-bleeding it may have eliminated some of the pedal squishiness I've always experienced. Any idea whether it'd be worthwhile to remove and bench-bleed the thing now after it's been installed for maybe seven years?

[Archangel]

Johny Know-it-all, I usually work on brakes of vehicles to which your cars are nothing more than a speed bump - oopsie, better watch out for them trucks with Michigan plates with a small "M" in the middle, you just may get lucky that tis one of these I've worked on and get yer ass run over due to air in its m/c.

Also, Johny Know-it-all, I actually do bench bleed the m/c, always, I just don't bottom it out - never have, never will, as long as every mechanic at work tells me not to, and the only one who claims it needs bottomed out is some prick on the internet.

[gadget73]

I've never bottomed out an MC. Usually I actually "bench bleed" them on the vehicle using the plugs that come with the MC. Or if you have a helper that doesn't mind sticking their finger in the hole while you pump the pedal, that works well too.

[Archangel]

Now these plugs I could never figure out how to use - open plug, push piston, close plug, release piston? I always use the fittings with the clear hoses, works like a charm.

[Blaze86Vic]

As far as performance is concerned, all air needs to be out of the system. Without bottoming out the pistons you can't get that last bit of air out.

So when you bench bleed an MC, exactly how much do you move the piston? I mean, really if you don't bottom it out on the bench, then how do you even have any idea how much you moved it, not all MCs have the same stroke? I've never seen an MC come with a piece of paper that says compress the piston 1-13/16". If you don't bottom out of the MC then why would you even bother bench bleeding, and why would they even tell you to?

I don't know it all, I know this. If you just think about it for a few seconds, what's going on inside the MC cylinder, you'd realize why you need to bottom it out. I'm sure all your brakes work great...... since 18 wheelers don't use hydraulic brakes......and since most people could drive with huge air pockets in their brakes and think that it's normal. Just visualize what goes on inside, and exactly what happens when you bench bleed it. It's very obvious.

[gadget73]

Now these plugs I could never figure out how to use - open plug, push piston, close plug, release piston? I always use the fittings with the clear hoses, works like a charm.

Yeah, something like that. I do like the tube kind better but you don't always get those with the MC and if they aren't on hand from a previous job...*shrug*

[Archangel]

Thain, if the new m/c is the Cardone brand then you get the plugs, they're too cheap to give you the rear deal. Fenco from Autozone comes with the clear hoses, and I've generally had much better luck with these than the Cardone ones.

Blaze, I know what you're talking about, tis just I've been told many many many times to make sure I don't bottom out the master cylinder cause air may go past the seals - no where this air is going to come from I ain't got no freakin idea, since he reservoirs are full and the hoses and fittings are tight. And don't even mention air pockets, I hate these damn things, my truck has some and tis really pissing me off now, such a shitty pedal feel!

[CheeseSteakJim]

Ivan, I don't want to offend you or your coworkers, but might it be possible that they're a bunch of older guys that are telling you this because maybe way back in the day the master cylinders were so low quality that it was bad to bottom them out? Maybe they don't realize that nowadays it's not a bad thing to do? It's kind of like how if you talk to ANY older guy who knows about cars, he'll say DON'T leave a battery on a concrete floor or it'll suck the energy right out of it - something that was true in the days of the rubber-cased batteries, but nowadays isn't true at all.