Clutch always in need of bleeding

[LyleC]

Looking for anyone who has had a similar problem like I have with my clutch.

History: New clutch master and slave cylinders in Nov 2018 at about 230k km.
A number of times over the past 12 months or so the clutch has become spongy sometimes to the point of losing clutch use altogether, and required bleeding.
I have had a 'power bleed' done by a mechanic with this gear, but the issue returned.
I then thought the problem was related to higher temperatures the slave cylinder and hydraulic line may be exposed to from the exhaust pipe when doing longer highway runs, and realized I did not have a did not have a heat shield at the slave cylinder as shown in the RAVE. But I quickly found that virtually no one has this heat shield, and I certainly couldn't buy one easily.
I did get some heatshield adhesive mat and wrapped the slave cylinder, but I think the problem is still there.

So I now routinely do a bleed of the clutch, but find no matter how long I bleed the system I keep getting some air bubbles coming though.
I do put the front up on ramps to get the right bleed position for the slave cylinder.

My question is, has anybody else experienced this.
Anyone experienced air being pulled into the system somewhere at the hose or connection fitting between the brake fluid reservoir and the clutch master cylinder?
The hose may still be original.
I have no hydraulic fluid leaks and have checked the plastic loop at the back of the engine.

Interested in the groups thoughts. TIA.

[Tins]

Anyone experienced air being pulled into the system somewhere at the hose

Given the pressure involved, it's unlikely air could get in without fluid coming out.

I suppose air could get in via the hose from the reservoir, but I would still think you would see some weeping, but maybe not.


I have no hydraulic fluid leaks



Are you sure? Have you checked the pedal end of the m/cyl? Just because it was new doesn't mean it was good. Ditto the slave.

Good luck.

[LyleC]

Are you talking about taking the master and slave out to look at the pedal end of M/C and slave push rod?

[Tins]

Are you talking about taking the master and slave out to look at the pedal end of M/C and slave push rod?

I don't have a manual D2 here to be sure but I'm pretty sure you can see the back of the m/cyl from under the dash. Might need to lift the carpet. Might also need to manipulate the rubber boot if the leak is only small. I think the slave would have to come out. Does it use much fluid?

169307

[Blknight.aus]

its the main seal on the MC along with a blocked breather on the reservior

[sierrafery]

Did you fit branded cylinders ? i've seen many cases when unbranded aftermarkets were DOA, happened to me too with slave cylinder, after a week of struggle to bleed the system i bit the bullet and fitted genuine and it's been OK since then, and it was about 7 years ago.

[LyleC]

Thanks for all the responses.
I've checked for leaks on the pedal side of the MC - evidence of previous leak, but noting now and no wetness under the boot.
Also no fluid at the bell housing drain plugs.

However, I think the MC was an unbranded one, possibly the slave as well.

When I've been bleeding the system, I had the reservoir cap off to keep topping up.
I still get air coming through, so I don't think cap breather blockage is the main issue.

Looking like a new MC, maybe a slave as well to make sure.

I was kind of hoping someone was going call out the MC plastic connection for the hose from the reservoir, or the rubber seal that this connector pushes into.
But no evidence of leaks here either.

[Tins]

Did you fit branded cylinders ? i've seen many cases when unbranded aftermarkets were DOA, happened to me too with slave cylinder, after a week of struggle to bleed the system i bit the bullet and fitted genuine and it's been OK since then, and it was about 7 years ago.

Yep. Just because it's new doesn't mean it's good...

[LyleC]

A couple of weeks ago I got the master cylinder changed with a 'good' one supplied by M R Automotive.
My mechanic said the old one looked like the new one but the markings 'weren't quite right', so probably a cheapy giving the problems.
He was good enough to do the job (and parts) for nicks since he supplied the first MC.
No issues since, including a Straddie Island trip at Easter.
Let's hope that was the issue.