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ttiiggy
Premium
join:2001-03-27
Bozeman, MT

master cylinder leaking

1994 Chevrolet Pickup.
The master cylinder has cracked again.
This is the fourth one in less than 2 years.
They are made of some kind of plastic.

Is this a known issue?
Is it just the ones sold by O'Really auto parts or would the one from NAPA or CarQwest be just as bad?
If I try OEM, is it going to be any different?

I think I wish I could find one made out of metal. I probably won't want to pay for it then.
...be better than not trusting it, though.




Doctor Olds
I Need A Remedy For What's Ailing Me.
Premium,VIP
join:2001-04-19
1970 442 W30
kudos:18

Is that where the line goes in? If yes then the line may be under a load or the line may be routed improperly.



mattmag
Premium,ExMod 2000-03
join:2000-04-09
NW Illinois
kudos:3
reply to ttiiggy


I have never run into such a repeat failure on one of those, and there are no metal ones available that I am aware of.

It is not very likely that the line could cause that issue, as it is plastic and would fail long before it could put that much load on the master.

Did you do the replacement yourself, or a shop? The one thing that comes to mind would be an improper assembly technique where the slave cylinder line is pinned to the master. If not done correctly, it could cause a crack in the area you noted.

Finally, I would never purchase parts from O'Reilly, or several of the other discount places. You get what you pay for is what I have found, so I would go with an AC Delco part, or alternatively Wagner or Dorman.



Vamp
5c077
Premium
join:2003-01-28
MD
kudos:1
reply to ttiiggy

Try searching a forum for your truck, maybe there is a vendor that sells aluminum ones, or a different vehicle that fits.

--
75/35 FIOS || MSN Msgr: scott001^gmail_com



ttiiggy
Premium
join:2001-03-27
Bozeman, MT
reply to mattmag

I stopped at O'Really and NAPA and CarQwest today. Where else is there?
They ALL had the EXACT same thing in their own branded box for ~$60.
Chevrolet dealer said they would have to order one for ~$170.

I just got another warranty replacement from O'Really.
See how long this one lasts.



Juggernaut
Irreverent or irrelevant?
Premium
join:2006-09-05
Kelowna, BC
kudos:2

Be careful not to over-torque the line fitting. I have a feeling that's the problem.



mattmag
Premium,ExMod 2000-03
join:2000-04-09
NW Illinois
kudos:3
reply to ttiiggy



So, are you doing the replacement, or a shop? Make sure you support the cylinder properly when you drive in the retainer pin. I really think that is the only thing that can be going wrong with so many failures like that.



ttiiggy
Premium
join:2001-03-27
Bozeman, MT

Click for full size
I am doing the replacement.

In the picture, there is still the white plastic dirt protector plug in the bottom of the outlet port.
The plastic tube that goes up in there has an 'O'-ring that seals around it.
There is a wider 'shoulder' on the tube that the o-ring comes down against. The tube has a groove in the side of the shoulder that a roll pin that goes crossways to the tube, through the hole in the body, slides past and just keeps the tube jammed up in there.
They give you a cotter pin to put through the roll pin to keep it from coming out.
If you remember ahead of time to push the roll pin into the first half of the hole in the body, just far enough to keep it in place, it is already lined up and straight and isn't so likely to get dropped as trying to get it in there after it is bolted onto the firewall.
I have always squeezed the roll pin into the hole with a pair of pliers instead of pounding it in with a hammer. I have tried to make sure that the pin is being pushed in straight and not getting cocked sideways with the pressure from the pliers.


mattmag
Premium,ExMod 2000-03
join:2000-04-09
NW Illinois
kudos:3

said by ttiiggy:

I have always squeezed the roll pin into the hole with a pair of pliers instead of pounding it in with a hammer. I have tried to make sure that the pin is being pushed in straight and not getting cocked sideways with the pressure from the pliers.

That's the best way to do it. In many cases, I would replace the master, line and slave cylinder as an assembly, but that was in the case of a failed cylinder, not broken. Maybe its just a run of bad castings? I don't know, but at least for now your aggravation is limited to time, and no cash being spent.


shdesigns
Powered By Infinite Improbabilty Drive
Premium
join:2000-12-01
Stone Mountain, GA
reply to ttiiggy

The only reason I could see it cracking there is if the plunger is bottoming out.



ttiiggy
Premium
join:2001-03-27
Bozeman, MT
reply to mattmag

Thanks.

It is just an old farm truck so it isn't critical. Not a daily driver. Got other vehicles to drive if this ones craps out. Keep a bottle of fluid behind the seat to get by... Just hope it isn't in a critical situation when it craps out.

CarQuest did (finally, after prompting) say that their listing showed a whole assembly available that they could order. They had no clue if it was the same make as what was on the counter or not. I didn't think to a$k how much $$.
O'Really and NAPA and even the Chevrolet dealer didn't have a listing for an assembly.



ttiiggy
Premium
join:2001-03-27
Bozeman, MT
reply to shdesigns

There is almost 1/2" extra before the plunger bottoms out.

I checked the throw. Push the new rod into the master and measure the depth. Measure the length that can stick out of the firewall when the clutch is pushed.



Ken Peterson
Premium
join:2000-12-08
kudos:3
reply to ttiiggy

Maybe on the next one you can do your own reinforcement add-on. Get some mesh and imbed it in some epoxy that you coat around the problem area - like fiberglass. Just a thought to strengthen the unit at the point of failure.



neonhomer
KK4BFN
Premium
join:2004-01-27
Edgewater, FL
reply to ttiiggy

said by ttiiggy:

Chevrolet dealer said they would have to order one for ~$170.

See if you can find a friend that has a commercial account with the dealer. Parts are a bit cheaper that way.

I usually buy stuff most of my stuff from Advance Auto Parts. I used to frequent Autozone, but their quality went to crap over the past few years.

However, there are parts I wont buy from Advance. Sensors and electronic parts I try to buy from the dealer.
--
"F is for Fire that burns down the whole town...
U is for Uranium...... Bombs...
N is for NO SURVIVORS!!!!!" Sheldon Plankton

Keep Calm and Carry On


Doctor Olds
I Need A Remedy For What's Ailing Me.
Premium,VIP
join:2001-04-19
1970 442 W30
kudos:18

said by neonhomer:

said by ttiiggy:

Chevrolet dealer said they would have to order one for ~$170.

See if you can find a friend that has a commercial account with the dealer. Parts are a bit cheaper that way.

Dealers usually gives shops only 10% discount off of the listed or suggested retail aka the counter price. You get a better deal by finding a GM/AC Delco/Delphi WD (Warehouse Distributor) that sells to the public.
--
What’s the point of owning a supercar if you can’t scare yourself stupid from time to time?


neonhomer
KK4BFN
Premium
join:2004-01-27
Edgewater, FL

said by Doctor Olds:

Dealers usually gives shops only 10% discount off of the listed or suggested retail aka the counter price. You get a better deal by finding a GM/AC Delco/Delphi WD (Warehouse Distributor) that sells to the public.

10% is 10%.....


Doctor Olds
I Need A Remedy For What's Ailing Me.
Premium,VIP
join:2001-04-19
1970 442 W30
kudos:18

said by neonhomer:

said by Doctor Olds:

Dealers usually gives shops only 10% discount off of the listed or suggested retail aka the counter price. You get a better deal by finding a GM/AC Delco/Delphi WD (Warehouse Distributor) that sells to the public.

10% is 10%.....

Yeah, but 20% to 30% discount is much better tasting IMHO. However any savings is great compared to no savings at all.
--
What’s the point of owning a supercar if you can’t scare yourself stupid from time to time?


mattmag
Premium,ExMod 2000-03
join:2000-04-09
NW Illinois
kudos:3

1 recommendation

reply to Doctor Olds

said by Doctor Olds:

Dealers usually gives shops only 10% discount off of the listed or suggested retail aka the counter price.

Your numbers are not correct, Dr.

In most all cases, the discount ranges from 20-30%, with GM as an example being 25% off of list. Many of the larger dealerships who provide parts delivery to repair establishments are often willing to negotiate even steeper discounts in exchange for steady business. The dealer that I purchased the majority of my parts from had me at a 32% break.