Clutch MC cup has oil in bottom?

[fisch]

Ok, the clutch pedal on my 521 goes right to the floor, no resistance. I checked the cup and it was full. (So it isn't loosing fluid, right?) No visible leaks around the MC. When I depress the pedal and look under the car at the slave, it doesn't move at all. Even with a full cup.

 

I sucked out the fluid in the cup of the MC, and there was what looks like oil in the bottom of it?

 

This vehicle has been sitting for 10 years.

 

I tried to trouble shoot this in Haynes and the shop manual with no luck.

 

Did a seal break around the piston, and allow oil/grease into the cup? Remember I know nothing!

 

Is my best shot to just replace the mc?

[tnip]

did you check that the pedal is actually depressing the piston? is there any leakage inside the cab or against the firewall, any leakage anywhere at all? you put fluid in and depressed the pedal a few times and nothing changed?

[fisch]

did you check that the pedal is actually depressing the piston? is there any leakage inside the cab or against the firewall, any leakage anywhere at all? you put fluid in and depressed the pedal a few times and nothing changed?

 

 

Yup it is depressing the piston for sure. I see no leakage inside the cab or on the firewall. When I think abut it, when I first bought the truck I think I saw fluid on the side of the cup, but it wasn't coming from the base of the cup, it must've come from the lid. But honestly it was so little it was hard to source where it was coming from.

 

I was a bit surprised when I looked in the cup and it was full of fluid after 10 years of sitting. Especially since the pedal goes right to the floor w/ no resistance.

[Fineline]

Sounds like a bad seal on the piston and old fluid to me. Replace or rebuild both the master and slave, entertain the idea of replacing the rubber hose, fill with new fluid, bleed, and your down the road. Brake fluid dosent like to sid idle for 10 years.

[kiznook]

never hurt to replace/rebuild all hydraulic parts. It's a good idea, ESPECIALLY with the brakes :eek:

[banzai510(hainz)]

did you bleed the line.

Do as the brakes bleed th fluid in a bottle till its clear and no bubbles and hold the clutch pedal down on the last stroke and tighten the bleed screw. Hopefully then it will work

 

Fill res open bleeder and pump fluid thru. No if no fluid come out by the slave cylinder something is wrong

[]2eDeYe]

Black in the fluid is a sign of rubber breakdown in the system. Time for new lines and disc brakes :D

[hang_510]

Did a seal break around the piston, and allow oil/grease into the cup? Remember I know nothing!

 

Is my best shot to just replace the mc?

 

yes(cracked after 10years) and yes

 

replace all of the rubber(MC/lines/seals) and you wont have to worry about whether or not youll stop in time :thumbsup:

 

i did it to mine and was worth it, stopping on a dime that is :w00t:

[fisch]

Cool new MC it is. Now, what is compatable with a 521 MC? Is a 510? What is the best place to get one?

 

I'd love to get a NOS one, but I will take what I can find!

[tnip]

if it was me, i'd be thinking about doing the disc brake conversion in the future so i would get the z mc and just do that part now. i don't have the best memory for years and whatnot, somebody else can tell you or you could probably find it if you search for it.

[Fineline]

I think he was talking about the clutch master and slave but I agree with your thinking.

[datzenmike]

Ok, the clutch pedal on my 521 goes right to the floor, no resistance. I checked the cup and it was full. (So it isn't loosing fluid, right?) No visible leaks around the MC. When I depress the pedal and look under the car at the slave, it doesn't move at all. Even with a full cup.

 

I sucked out the fluid in the cup of the MC, and there was what looks like oil in the bottom of it?

 

This vehicle has been sitting for 10 years.

 

I tried to trouble shoot this in Haynes and the shop manual with no luck.

 

Did a seal break around the piston, and allow oil/grease into the cup? Remember I know nothing!

 

Is my best shot to just replace the mc?

 

2eDeYe;23599'']Black in the fluid is a sign of rubber breakdown in the system. Time for new lines and disc brakes :D

 

Brake fluid is a high boiling point, hydraulic fluid but is not petroleum based. This allows rubber seals to be used that would dissolve in a petroleum environment. It has the nasty property of absorbing water from the air. Water in a hydraulic system will corrode (rust) ferris metal parts and lowers the boiling point of break fluid, not good. NEVER use any petroleum products in your break or clutch system like WD-40, gas, oil, paint thinner, ether. It will damage the rubber parts. Ideally, the fluid should be replaced every two years if you love your hydraulic systems.

 

Ten years is a long time for the fluid to break down and absorb water. Loosen the bleeder on the slave and it will usually siphon down hill. Keep the master filled with clean new fluid and drain until clear. Pumping the master will speed up the exchange. With new fluid and no air it MIGHT start working but it's just a matter of time before you have to replace.

[tnip]

I think he was talking about the clutch master and slave but I agree with your thinking.

 

whoops... i forgot... :D

[]2eDeYe]

Haha, I can't read either :P

[yello620]

But, the idea is the same for your brakes. Same style of components, same fluid. Are you really going to trust those rotten old seal in your brake system. Just replace all the parts with rubber in them before your are trust them in traffic. This really isnt one of those things that anybody should be screwing around with, fix it right. You have no pedal pressure for a reason, it is giving you a hint.

 

Jason

[fisch]

Sounds like solid advise all around fellows. Thanks!

 

For aftermarket replacements, what's best?

 

Beck/Arnley

Raybestos

a1 Cardone

[]2eDeYe]

All of those are decent quality...I'd prolly even start in that order ;)

[yello620]

All those are good. Do yourself the favor, and DO NOT purchase remanufactured master cylinders. Spend the few extra dollars and get new ones. Then when installing them, make sure to bench bleed them without overstrokeing the cylinder. Overstroking the cylinder CAN ruin the seal in the new part. Then you will continue to fight the no brake problem while thinking you have all new good parts.

 

Jason

[fisch]

Then when installing them, make sure to bench bleed them without overstrokeing the cylinder. Overstroking the cylinder CAN ruin the seal in the new part. Then you will continue to fight the no brake problem while thinking you have all new good parts.

 

Jason

 

I've never bench bled. Does it go like this?

 

-Put MC in vise,

-run a hose to a can with a little fluid

-fill cup

-pump and refill until no air bubbles

-put on cap and install

 

But how do i avoid overstroking the cylinder? Will I feel resistance when at full stroke and know to stop?

[vindats1]

yep, fluid is old and the rubber breaks down...same as everyone else said....replace both, all better!

[datzenmike]

LOL just use many short strokes till you get results.

[fisch]

LOL just use many short strokes till you get results.

 

HA! I KNEW someone was going to go there! Just didn't know who!

[kiznook]

tokiko, nabco, or sanyco

[fisch]

tokiko, nabco, or sanyco

 

True enough Kiznook, but where to find them? I've tried importedcarparts.com with no luck. Google isn't helping me there either.

 

Are they really worth the extra cash? I don't have enough experience to know. I don't mind spending the extra if people have had problems w/ the Beck/Arnley for instance. I don't want to put crap in there! But for something as simple as a M/C, if it is does its job well, why not use it?

[kiznook]

I'm sure they'll all work the same. BUT I like to buy the best when it comes to stuff like this.

 

I know I can get 510 clutch M/C for $25 and ZX brake for $115, but I don't know about the availability on the truck parts. But I'm sure if B.A. makes it, theres probably something better out there.

 

It's worth looing around