ajhale

I have some questions for the clutch hydraulics experts out there. I've been having the common problem of getting air in the clutch system on my 98 T/A. I have recently replaced the clutch, master and slave cylinders (all Luk OEM level), and done the drill mod on the line.

After I bleed the system with the bleeder screw OR using a mityvac from the reservoir it seems fine until I do fairly high RPM shifting again. But the strange thing is that if I rev the engine at all prior to shifting, even to 4000 or 4500 RPM, and then a slow granny shift, afterwards, the problem comes back. Afterwards, I go to shift to other gears and it feels like I am locked out of them until I am persistent enough. Even stopping at a stop sign later, I find it is hard to get into first gear.

My question is why would engine RPM have anything to do with whether the hydraulic system allows air in? The system appears to be a closed system - just the master cyl, hose, and slave cyl - with no connections to the engine or engine vacuum.

Another thing that I noticed is that when I bleed the system with the Mityvac from the reservoir, I can remove all of the air bubbles with the pedal released, or after it has been pumped. However, if I have a friend hold the pedal down while I apply ~12 in-Hg of vacuum, I can pull large bubbles out all day long. Is this abnormal? I'm not sure if applying vacuum while the clutch pedal is pushed in is a valid case, since it is not normal for the system to see vacuum from the top anyway. I did have to wrangle the master cylinder pretty badly when I installed it, so all of the above stuff makes me think I may have damaged it. I'm planning on changing the master tomorrow and this time I'll remove that silver pipe that runs along the driver's side of the engine so I can get my arm and the master cylinder down into position more easily.

Thanks for reading and for your ideas...

jmd

iTrader: (4)

Bleed it using the JMD method (see post #2)

I've had better luck with that than anything else.

SladeX

Is your clutch line protected from heat? sounds like you may be boiling it.

ajhale

Thanks for the quick replies!

I may try the diff method of bleeding.

And no, I'm not protecting the line from heat other than by using what was in place from the factory (routed under that flat metal heat shield). I've heard of people using heat resistant tape, and spark plug wire heat shield casings, etc.

ajhale

Do you guys change the O-ring on the quick connect fitting end of the braided hose when you do a master swap? My O-ring looks OK, but this will be the second time I have had the hose out and back in and I don't want to wonder whether it's giving me problems. I guess I can pick a new one up at Autozone.

SladeX

new stock master will have a new braided line and hence a new o ring.

ajhale

I bought a new one from Autozone that did not come with a new braided hose. I had to reuse my old one. I believe a new GM unit does come with the new hose.

I picked up a new O-ring today and I'll finish the job tomorrow.

ajhale

How the hell do you get the quick connect fitting to reconnect? I've done this before and I don't remember it being such a pain in the ***. I have the bleeder screw on the slave opened pretty far to relieve internal pressure (and fluid is dripping out). I'm just trying to push the hose in... do I have to do anything with the white plastic disconnect ring?

The new o-ring I put on is slightly fatter than the old one, but not significantly. I wonder if that's giving me problems.

Any tips appreciated. Thanks!

SladeX

If it appears visually larger, it will be a pain to push in. It'll take some leverage but you might be able to pull it off if you can apply even pressure from all around. Also try lubricating the o-ring with a little brake fluid as well. Seems strange that it is larger, this is a GM o-ring replacement, right?

ajhale

No, this is a National brand, parts shelf o-ring from Oreilly that I picked up last night. The ring has the same diameter as the one I pulled off, but the rubber is thicker.

ajhale

I got impatient and put the original o-ring back on and the hose popped right in. So there's no extra room for a slightly wider o-ring.

Almost done.