Clutch bleed

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G

Gunny

New Member
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184
Location
West sussex
I have a discovery 1994 200tdi, I have just replaced the clutch and lever, I fitted the slave cylinder through it's plate which also has another I am told a damper on it, I blead from the slave cylinder until all air had gone, but I still have no clutch, theres no leak from slave, any ideas what the problem could be chaps
 
Gunny said:
Why is there a need for the damper, why not just deliver the presure straight to the slave, as on rangys
Click to expand...

The damper prevents engine pulses being transferred hydraulically to the clutch pedal.... removing it u might have a trembling in the pedal.... not a big problem taking into account that u dont have your foot allways on it.
 
The clutch reservoir and all pipe work including the slave cylinder is completely independent of the engine, the whole assembly is identical to that of the classic range rover, which is fed by a single pipe from the reservoir, the significance of the so called damper on the Discovery to me simply fails to make any sense, I have used and maintained a few diesel engines over the years and this is the first time I have come across this set up, even the scourge of diesel engines crosses his fingers( VM ) 2.4 engine put in the classic rangy didn’t have this set up. I will remove this damper and set up the system with a single feed thus eliminating air pockets. I thank you all for your help with this problem and look forward to more landy chat.
 
I replaced the slave cylinder today and then tried to bleed the system again, no good, so I removed the feed line from the master cylinder and got a mate to gently pump the clutch pedal while I put my thumb over the mater cylinders opening, felt the pressure so thought ok, but no, so I bypassed the damper and fed straight into the slave still no good, I finally found the master cylinder is at fault, on order. I did also speak to a land rover specialist about the so called damper; he told me the damper has no function at all other than to route the fluid in a u.
 
Believe me i didnt try to misslead you about the damper... i've spent the last 3 years studying Land Rover's technology (in theory, as a hobby;)). As u know the engine is attached to the gearbox so is the slave cylinder... the engine pulses/vibrations are transferred into the gearbox implicitly the clutch and going through the pressure plate > release bearing > fork > pushrod > slave cylinder piston > brake fluid > master cylinder piston > pedal. ... the other way around as your foot's power translates from the pedal untill the pressure plate. ... after a proper bleeding this damper will not worsen the clutch's behaviour at all.

See RAVE > Workshop manual 33-1-6, third paragraph >
"The master cylinder comprises a body with a central bore. Two ports in the body connect the bore to the hydraulic feed pipe to the slave cylinder and the fluid reservoir. The bore is also connected to a damper which prevents engine pulses being transferred hydraulically to the clutch pedal. A piston is fitted in the bore and has an external rod which is attached to the clutch pedal with a pin....."

Theoretically there is the possibility to have some rev fluctuations(or even loose cruise controll if fitted) without touching the pedal cos the clutch switch might get a pulse(with no damper to eliminate that) and "think" that the pedal was depressed... then it will send a signal to the ECM > "The clutch switch is located at the rear of the engine compartment on the RH side. The switch is operated by hydraulic pressure when the clutch pedal is pressed. The ECM uses the signal from the clutch switch for the following functions:
l To cancel cruise control if operating.
l To provide surge damping during gear change.
Surge damping stops engine speed rising dramatically (engine flaring) during gear change. Surge damping assists
driveability as follows:
l Smoother gear change.
l Greater exhaust gas emission control.
l Improved fuel consumption." so i wouldnt mess with that damper

this is the pure theory... but if a specialist tells something else then i rest my case:rolleyes:
 
Last edited:
you are right mr sierrafery or at least as ive allways understood it ,but for most removing would be a help rather than a hinderance
 
jamesmartin said:
you are right mr sierrafery or at least as ive allways understood it ,but for most removing would be a help rather than a hinderance
Click to expand...

I admit that the theory might not be down to earth sometimes but in this case i cant underdstand what benefit is for the hydraulics to remove that guiltless damper....and if u gain some pressure removing it would'nt that bring closer the slave cylinder's death ?
 
true but they do wear themselves and is often easier to remove than replace although depends on customer as with alot of these things preference is more powerful than logic, and lr dont fit them to all systems that are the same on different vehicles , they are only a small accumalator , i love the theroy and to know reason for fitting but not with these dampers but later things like permable seals in modern gear box bearings to proplong life while obviously not protecting baulkrings that are subseptable to dirty oil ,instead of changing oil has more of a business feel than logical engineering basis,are you an engineer or just interested ,youd be surprised what some mechanics dont know and what badged overalls give in confidence to some people, i have scruufy overalls as they get dirty and damaged ,but it does lower my knowedge according to some by wearing them
 
I've graduated an academy of aeronautics - avionics engineering/aircraft building section but not working in this specific field now... I'm studying L R systems as a hobby using my technical knowledge(mainly D2 due to obvious reasons:)) ....though i've realised that sometimes is easyer to fix an aircraft than a D2 ... especially when it comes about bleeding a clutch:D
 
i like to do more theroy work but didnt go to university and wheresas i used to work for a company that allowed me to do alot and found it interesting ,price seem the only criteria now engineers find ways to save a penny each year instead of spending one on an improvement to the point they will be like washing machines ,throw away when broken or 6 years old ,short term outlook i think
 
sierrafery said:
Believe me i didnt try to misslead you about the damper... i've spent the last 3 years studying Land Rover's technology (in theory, as a hobby;)). As u know the engine is attached to the gearbox so is the slave cylinder... the engine pulses/vibrations are transferred into the gearbox implicitly the clutch and going through the pressure plate > release bearing > fork > pushrod > slave cylinder piston > brake fluid > master cylinder piston > pedal. ... the other way around as your foot's power translates from the pedal untill the pressure plate. ... after a proper bleeding this damper will not worsen the clutch's behaviour at all.

See RAVE > Workshop manual 33-1-6, third paragraph >
"The master cylinder comprises a body with a central bore. Two ports in the body connect the bore to the hydraulic feed pipe to the slave cylinder and the fluid reservoir. The bore is also connected to a damper which prevents engine pulses being transferred hydraulically to the clutch pedal. A piston is fitted in the bore and has an external rod which is attached to the clutch pedal with a pin....."

Theoretically there is the possibility to have some rev fluctuations(or even loose cruise controll if fitted) without touching the pedal cos the clutch switch might get a pulse(with no damper to eliminate that) and "think" that the pedal was depressed... then it will send a signal to the ECM > "The clutch switch is located at the rear of the engine compartment on the RH side. The switch is operated by hydraulic pressure when the clutch pedal is pressed. The ECM uses the signal from the clutch switch for the following functions:
l To cancel cruise control if operating.
l To provide surge damping during gear change.
Surge damping stops engine speed rising dramatically (engine flaring) during gear change. Surge damping assists
driveability as follows:
l Smoother gear change.
l Greater exhaust gas emission control.
l Improved fuel consumption." so i wouldnt mess with that damper

this is the pure theory... but if a specialist tells something else then i rest my case:rolleyes:
Click to expand...
I did not think you were trying to muslead me, Common sense tells me that the clutch damper on an mk1 discovery is completely unnecessary, it simply serves no purpose . I go back to the Range rover classic which has the diesel engine but does not have the same clutch damper set up, the Discovery is based on the same vehicle.
You use quote ([FONT=&quot]Theoretically there is the possibility to have some rev fluctuations(or even loose cruise controll if fitted) without touching the pedal cos the clutch switch might get a pulse(with no damper to eliminate that) and "think" that the pedal was depressed... then it will send a signal to the ECM > "The clutch switch is located at the rear of the engine compartment on the RH side. The switch is operated by hydraulic pressure when the clutch pedal is pressed. The ECM uses the signal from the clutch switch for the following functions:
l To cancel cruise control if operating.)[/FONT]
[FONT=&quot]The Discovery mki does not have cruise control, the Discovery does not have clutch switch and Discovery mk1 does not have ECM, the comments in this paragraph are for a RAVE.[/FONT]
 
:frusty: ... just now i've realised that yours is a 200Tdi.... i missed that.... off course for D1 my comments are absonant... sorry:eek:
 
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