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Boater
02-12-2013, 01:26 AM
Last time I rebuilt the engine I forgot to bleed the clutch and found the biting point very low, until I got about 100 miles from home and stopped for a meal and the clutch wouldn't disengage until I bled it (in the car park). After that it seemed fine.

This time I have refitted the engine and gearbox and thought of bleeding the clutch so attached my eezibleed and purged all the air out of it, yet the biting point is very low once again.

I am trying to work out what is normal for these:
- How high should the biting point be, I really have forgotten (been apart for a long time)
- Should the clutch pedal come all the way back up until it stops or is there normally excess range? The pedal return spring does not seem to be mounted in a way that would ever bring it any higher.
- Although Haynes suggests using a pressure bleeder, do I need to bleed this by pushing the pedal instead?
- Is this a sign of master cylinder problems?
- Do I just need to drive around for a bit to settle the clutch in (note that the clutch is not resettable like the one in Haynes book)

I just can't work out why it's not improving with bleeding and I'm not keen to lose the ability to select gears at some random point in a journey - I was lucky to be parked with plenty of space around last time.

Eric Experience
02-12-2013, 09:21 AM
Boater.
Could be a master cylinder problem, to find out clamp the hose with vise grips, the pedal should be solid if not you need to have a look at the master cylinder. Eric

Boater
02-12-2013, 11:14 AM
Cheers Eric - hose to slave cylinder or hose from reservoir to master? I'm thinking the former.

Boater
02-13-2013, 09:42 AM
Well, put 2 brake hose clamps on the hose to slave cylinder (couldn't be bothered to jack it up and not sure if either was as tight as possible) and the pedal was firm. It did move under a lot of effort, but that was most likely fluid bypassing the clamps at high pressure. So I think the master cylinder is OK.

Actually the biting point feels ever so slightly higher after doing that.

Trying to visualise how the internals of the slave cylinder work, seems to me that if the pushrod is only stroking out far enough to release the clutch at the very end of the pedal stroke maybe I have air on the return side of the piston which I am bypassing by not pressing the pedal - I think some old fashioned pedal bleeding is in order. Probably not tonight, when I looked out of the window this morning I thought someone had bleached my lawn, and then realised that everything had turned white.
Should have just done it last night but I was in diagnostic mode and running around looking at other stuff too.

I have reviewed my re-assembly photos and can't determine much at all - although I can see the drive plate through the fingers, I can't see the T mark I made on the gearbox side, nor the E mark which would indicate I fitted it backwards despite marking it.
2 days ago I was looking at my car suspension which has baffled me for a few weeks now and eventually spotted I fitted the nearside ARB bush to the wrong side of the bracket (over a year ago) skewing the anti roll bar and making the car ride an inch lower on the offside than the nearside - therefore I am always open to the possibility of human error!

Andyandyandy
02-15-2013, 01:12 AM
I'm not familiar with this particular setup, but is there any adjustment either where the slave pushrod connects to the fork/lever or in the pedal linkage? With cable and rod linkages you can often change the engagement point by quite a bit. I don't have much experience with hydraulics though. I wish I could have a manual gearbox in my van. No such luck for NAFTA.

Boater
02-15-2013, 01:58 AM
Well tonight I had another go at bleeding using the pedal, and then using the pedal and the eezibleed and the pedal feels better (didn't actually start up and try to pull away because I parked the car close), however I have just had an epiphany of sorts!

RTFM!!!!

If you have 2 workshop manuals, read them both!
Haynes describes the normal pressure assisted bleed method that I have used on my car brakes and clutch, saying simply open the slave cylinder bleed screw until the bubbles stop.
Russek mentions that MB use pressure bleeding and then goes on to describe a home procedure which involves connecting one end of a tube to a brake bleed screw, pumping the brake until the line is clear of air and then connecting it to the clutch slave cylinder bleed screw, and opening that. Then you push the brake pedal down (an assistant required), close the brake bleed screw, let the pedal return, open the brake bleed screw, and repeat until there are no bubbles coming up in the reservoir - i.e they are saying to reverse bleed the clutch.

I am now pretty confident that the problem is/was air in the slave cyclinder which does not bleed out under normal methods, I think (hope) I got it with the pressure and pedal together, if not I'll be giving that reverse procedure a try when I can find an assistant!

Learn something every day!

Boater
02-15-2013, 02:03 AM
I'm not familiar with this particular setup, but is there any adjustment either where the slave pushrod connects to the fork/lever or in the pedal linkage? With cable and rod linkages you can often change the engagement point by quite a bit. I don't have much experience with hydraulics though. I wish I could have a manual gearbox in my van. No such luck for NAFTA.

No adjustment, hydraulics are self adjusting as long as you bleed them. The master cylinder is connected directly to the pedal, the slave pushrod connects directly with a semi-sperhical dimple in the yoke.

Not sure I would like an auto box at all - might find out in May if I get a rental car for a couple of days whilst I'm in Las Vegas!