MGF clutch pressure loss.

ewyasrover · Post by **ewyasrover** » Sat Jun 16, 2018 4:14 pm

Had a new clutch master cylinder fitted back in February, all was fine until 2 weeks ago and suddenly lost clutch pedal pressure.
Limped the car home, my mechanic's opinion was that the master cylinder had failed as there was no fluid loss and no obvious leaks.
Bought a new master cylinder, towed car to my mechanics garage clutch system checked out and new master cylinder fitted.
Had car back Wednesday, took it for a 30 mile drive, all was well. Went out today covered around 25 miles, lost pedal pressure again!
Once again limped car home. Same symptoms, no fluid loss, no pedal pressure. Surely the new master cylinder has not failed already?
It's a genuine oe part from a well respected supplier, as was the last one. Anyone got any ideas, or experience of this fault?

talkingcars · Post by **talkingcars** » Sat Jun 16, 2018 10:33 pm

What condition are the other components in?

ewyasrover · Post by **ewyasrover** » Sun Jun 17, 2018 7:46 am

Slave cylinder newly fitted just before I bought the car 2years ago. Pipework all seems sound with no obvious leaks and fluid level in master cylinder has not dropped at all.

Charless · Post by **Charless** » Sun Jun 17, 2018 8:24 am

Maybe a sticky release arm?

ewyasrover · Post by **ewyasrover** » Sun Jun 17, 2018 11:09 am

Don't think it's the release arm, it was given a good lubing when master cylinder was fitted.
I regularly give it a spray lube and it seems fine.

ewyasrover · Post by **ewyasrover** » Sun Jun 17, 2018 5:31 pm

Tried bleeding clutch at top of master cylinder and through slave cylinder bleed screw.
No result, pedal still on floor. losing heart with this great little car now, any ideas before I crack and buy an MX5?

Charless · Post by **Charless** » Sun Jun 17, 2018 5:45 pm

The release arm cleverly has a seal, designed to prevent ingress of sh*t - which admirably prevents penetration by externally administered lubricants too. I assume you have the engine cover off and can see the slave rod operating?

ewyasrover · Post by **ewyasrover** » Sun Jun 17, 2018 6:10 pm

Yes Charless, checked actuating arm working as it should after fitting new master cylinder.
At a loss to explain this problem, it's p*ssing me off now!

Bazzajay · Post by **Bazzajay** » Sun Jun 17, 2018 11:54 pm

If you have found no leaks in the system and there has been no fluid loss that would indicate that there is a failure in one of the components. You have replaced the Master Cylinder and the problem has not been resolved. All other components seem to be working. It therefore seems to point at the Slave Cylinder as the faulty component. You say it was replaced a couple of years ago before you acquired the car. Do you know how it was sourced? It may not be an OEM or other recommended part. May be worth changing this before ditching the car.

RobboMC · Post by **RobboMC** » Mon Jun 18, 2018 3:22 am

could there just still be air in the system from not being bled properly??

These things are not the easiest in the world to bleed as the slave cylinder is down the back of the car and the pedal has no decent return spring.

Perhaps a good bleed by a different mechanic might help.

ewyasrover · Post by **ewyasrover** » Mon Jun 18, 2018 7:15 am

I won't ditch the car! That was just a mad moment of sheer frustration, Speaking to my mechanic today and will pass on all advice given on here. Thanks guys, if we resolve this problem I'll post the result here, it may help someone else with a similar problem.

BodgeItAndScarper · Post by **BodgeItAndScarper** » Fri Jun 22, 2018 12:01 pm

ewyasrover wrote:Surely the new master cylinder has not failed already?

I've had bad experiences with new-old-stock hydraulic cylinders (on other cars) failing shortly after installation because they'd sat around in a warehouse for so long the rubbers had deteriorated. So I wouldn't rule it out completely. But I'd take a good look at the slave cylinder too. My F had a dodgy seal on the slave which allowed it to suck in air - but no fluid was coming out, so no sign of a leak. Worried me a bit, ended up being a very simple fix

Since you say you're not losing fluid, the slave sucking in air sounds like a good bet. If I remember rightly, I could bleed the system, the clutch would work for a few pedal pumps and slowly stop actuating - I could hear air being sucked into the system when the pedal was released.

ewyasrover · Post by **ewyasrover** » Fri Aug 03, 2018 2:40 pm

Clutch problem solved!
Although the slave cylinder looked fine it was a pattern jobby, replaced with a genuine AP Lockheed item and clutch now works fine.
Moral of the story, fit genuine parts! Many thanks to the guys at Just Right Autos and Steve at Everest Motors Tewkesbury for all the helpful advice.

The MGF Register Forums

MGF clutch pressure loss.

MGF clutch pressure loss.

Re: MGF clutch pressure loss.

Re: MGF clutch pressure loss.

Re: MGF clutch pressure loss.

Re: MGF clutch pressure loss.

Re: MGF clutch pressure loss.

Re: MGF clutch pressure loss.

Re: MGF clutch pressure loss.

Re: MGF clutch pressure loss.

Re: MGF clutch pressure loss.

Re: MGF clutch pressure loss.

Re: MGF clutch pressure loss.

Re: MGF clutch pressure loss.