Clutch Reservoir Rubber Cup

[Garrcus]

Hey Guys,

85 Chevy K10/Manual

Quick question, I got a full service today and the tech checked the brake/clutch fluid levels. He pulled the rubber cup that sits directly under the clutch fluid reservoir cap. It was quite swollen which he said could be a sign that some other kind of fluid got in the system. Is this true? Or is it simply old?

Also where can I find a replacement rubber cup? I have searched online to no avail, I may not have the proper terminology when searching.

Any Help is greatly appreciated.

[bake74]

      It depends on what he means by "other kind of fluid", Yes there are certain fluids that can make the rubber seal/boot you are talking about to swell, but I don't know how they would get there.
      More than likely your clutch cap rubber seal/boot is just bad.  Try looking up clutch reservoir cap, then it might show a listing for just the rubber seal/boot portion.

[bd]

Here are some possibilities for the gasket:
http://www.autozone.com/autozone/parts/1985-Chevrolet-K10-1-2-ton-P-U-4WD/Master-Cylinder-Gasket/_/N-ijkpvZ8kngm

Are you the original owner?  Is it possible someone added a little power steering fluid or some other type of oil to your master cylinder by accident, or cleaned the M/C cap/flushed the system with a petroleum based solvent?  Rubber swells when exposed to petroleum solvents and oils.  At the very least I would flush the system, replace the cap gasket, and inspect for fluid leaks at all the wheel cylinders and calipers.

Oh!  And, welcome to the site!

Edit:  Oops clutch slave cylinder not wheel cylinders....  Where was I? 

[Garrcus]

Hey thanks for the input guys,

No I am not the original owner, have had the truck for about 7 months now and have replaced all sorts of stuff on it myself and basically learning as I go. My wife hates my new found hobby but I Love IT and wish I had taken an interest in mechanics earlier in life.

Anyway, the tech also mentioned that people will pour all sorts of different types of fluids into the wrong systems by simply not knowing what they are doing. However, I am wondering if this boot was even originally intended for this reservoir. Take a look at the pics (some with boot in reservoir as found and then also the boot removed) and let me know what you guys think. Overall the clutch is working great and have not had any problems thus far.

Also I ran by Autozone and picked up a Master Cylinder Gasket (also pictured) to see if my theory about this boot being some make shift stop gap by the previous owner was correct. However this new gasket also did not fit.

Do I need to start searching some junk yards?

Thanks again.

[Garrcus]

Update:

I called the dealer and they said that GM has discontinued that seal. Called the local junk yards and they didn't have anything either. So went back to auto zone to try and see if I couldn't just replace the entire assembly with a newer set up to avoid not being able to find parts.

The guy who helped me knew exactly what I was talking about and pulled a clutch master cylinder from a 91 through 97 jeep cherokee, he took the cap off and tried it on my reservoir. Turns out that cap has the seal in the cap itself and is a perfect match. However they do not sell the cap by itself but only as part of the master cylinder which is $50. So I called Dodge and am having them order the part which is still $25. Seems a bit expensive for a such a simple part.

If anybody else has any other ideas let me know,

And thanks again for the feedback.

[jaredts]

I'm not totally sure what I'm looking at in the pics, but it looks like your reservoir just ran low and sucked it in (which of course would mean a leak).  Are you losing fluid?

[87454westernhauler]

im not sure if u need that gasket. i dont think that any of my trucks have ever had a gasket in clutch resivor . 

[thirsty]

I agree with jaredts...it looks like you have a leak to address also.
That was a good deal finding another one for your reservoir. Mine is looking like a used condom too!

[thirsty]

im not sure if u need that gasket. i dont think that any of my trucks have ever had a gasket in clutch resivor . 

It's a bladder like in the brake master cylinders. I believe they are there so you don't introduce air into hydraulic system.

[87454westernhauler]

ok.. ill need to look at both my 87s next time im home and look again. hum..?

[VileZambonie]

Yes you need the rubber cap. Brake fluid is hygroscopic which means it absorbs moisture. The seal could have swollen due to water or contamination. I agree, flush and fill. Replace the cap or put a new reservoir if you can't find one.

[thirsty]

Yes you need the rubber cap. Brake fluid is hygroscopic which means it absorbs moisture. The seal could have swollen due to water or contamination. I agree, flush and fill. Replace the cap or put a new reservoir if you can't find one.

^This^ guy has all the answers.
Thanks again Vile for another detailed answer.

[Garrcus]

Hey Thanks again guys for all of your feedback,

I don't think that I am leaking fluid but I know that the previous owner told me that he replaced the clutch within a few months before I bought it, perhaps he never filled the reservoir up properly but I will definitely flush and re-fill. I have never done that procedure before any tips?

Another question comes to mind, is that seal normally contained in the cap and through whatever went wrong sucked into that position. Or in other words is that the normal condition of the seal or was it vacuumed into that condition because of dead space, leak or other situation. Are your seals more in line with my last pic that I posted of the seal that fits later models or the cup like shape of mine.

Thanks again.

[zieg85]

If I remember right it is a cup like kind of the size of a K-cup from a Kerig, the ridge at the top is the gasket.  It is about 1.25" or so deep and if you overfill it makes a mess.  My hose going to the clutch master is cracked real bad.  It would be nice to know if anyone knows of replacement parts for all the hydraulic parts

[1980c10]

It is cup shaped. If you can get it to lay flat and it stays that way and your clutch works as it should, I would leave it.
Zeig just get a pice of hose that is the same size from your local parts store.
as far as the line; A brake line can be used in between the clutch and slave cylinder.
There is no reason to touch any of the hydraulic clutch linkage to replace a clutch, except maye to move the slave cylinder out of the way.
Both the clutch and slave cylinders are available in your local parts stores.