Hi guys

 

I’ve just pulled up in my 300 and as I came to a slow there was a little smoke coming up from the engine bay up by the windscreen. As I dipped the clutch the clutch pedal hesitated to return to it “off” position. I then reversed back into a parking space and I couldn’t disengage the clutch and had to stop the car by turning the engine off and brake (before hitting the car behind me). I had notice the clutch slip on the way up to my destination. There is also a puddle of clear oil forming under the car, not much but enough to have me worried.

 

 

 

Does this sound like the clutch has gone or something more sinister? I had the gearbox out a few thousand miles ago and there was loads left in the clutch.

 

Cheers,

Chris.

Just tried to move the car and there is no resistance on the clutch pedal.

What's the level on the clutch master cylinder reservoir? The clear fluid is probably hydraulic clutch fluid. The clutch master

cylinder is directly above the o/s exhaust elbow. See if there is evidence of fluid leaking from it or the pipework/union.

Is this it, just behind the brake master cylinder?

 

 

It’s not got any fluid in it. :sad:

That's the one.

Well there was no evidence of a leak at the master cylinder (other than it was

empty). After going back to the car today and trying to top it up there was still no luck. It seems the leak is lower down and I’ll have to jack her up to have a proper look to see what needs replacing. But for now the car is back home and in the garage.

 

 

If you have any advice or links that will help me locate and solve the problem I’d be very great full as I think I’d like to try and tackle the job myself if I can.

 

Cheers,

Chris.

 

P.S. Would this problem have the potential to cause the clutch to slip?

Would this problem have the potential to cause the clutch to slip?

 

Yes it could if air got into the system - which is very likely as your reservoir was empty. Any air in the clutch lines will expand greatly

compared to the hydraulic fluid. As the air heats up, the clutch engagement point can move closer to the start point of pedal travel.

Even with your foot off the pedal the expanded air keeps constant pressure on the clutch slave cylinder, resulting in slippage.

I’ve just had another thought! Is clutch fluid corrosive, do I need to wash off any clutch fluid that has escaped either from the initial leak or spillage from my topping up/bleeding?

Dot 3,4 and 5.1 (glycol ether based) will damage painted surfaces if left on for very long. Think paint stripper!

Thanks Andrew, I’ll make sure I give the engine bay a good wash down just in case.

I just found these videos, they look very useful and hopefully others may find them helpful.

 

 

P.S. Would this problem have the potential to cause the clutch to slip?

 

 

 

No

 

 

 

 

Yes it could if air got into the system - which is very likely as your reservoir was empty. Any air in the clutch lines will expand greatly

compared to the hydraulic fluid. As the air heats up, the clutch engagement point can move closer to the start point of pedal travel.

Even with your foot off the pedal the expanded air keeps constant pressure on the clutch slave cylinder, resulting in slippage.

 

How can this be possible the system by description has leaked fluid and so is no longer a sealed system, any air expansion ( unlikely ) would simply escape out of the same leak point.

 

 

Jeff

If the cylinder's seal has an intermittent failure, for example the tip of the seal in the cylinder is worn/damaged or folded back on

itself then it is entirely possible for the system to be holding pressure and then start to fail again leaking fluid past the seal. I've

personally experienced this problem with a seal. Eventually the seal will completely fail.

 

If this is the case in Chris's car the system can be sealed on occasion and the air expansion problem can manifest itself. The best

thing to do is to replace the cylinder, bleed the system and see if the clutch still slips.

If the cylinder's seal has an intermittent failure, for example the tip of the seal in the cylinder is worn/damaged or folded back on

itself then it is entirely possible for the system to be holding pressure and then start to fail again leaking fluid past the seal. I've

personally experienced this problem with a seal. Eventually the seal will completely fail.

 

If this is the case in Chris's car the system can be sealed on occasion and the air expansion problem can manifest itself. The best

thing to do is to replace the cylinder, bleed the system and see if the clutch still slips.

 

 

 

Erm...well that is a theory, also Kennedy was shot by the FBI

 

Jeff

Erm...well that is a theory, also Kennedy was shot by the FBI

 

Jeff

 

That’s incorrect, Kennedy was killed by Elvis. Also, Elvis is still alive today, he lives in the Bahamas in a room share with Hitler.

 

Chris, it looks like you need a new clutch slave cylinder, or a rebuild kit.

I’m hoping to get her in the air Thursday morning and have a good look through the system. Is it worth replacing both the master cylinder and slave at the same time as the fluid is on the floor now or do they not tend to pop around the same time?

 

Also there seems to be quite a price difference between suppliers. I assume the cheaper listed items are poor copies or is it a case of Nissan parts department trying to pull my pants down?

 

Cheers,

Chris.

I would get the car in the air first and establish were the leak is coming from. The clutch slave cylinder is straightforward

to replace. I used an OEM part when I replaced mine, but there may well be pattern parts available that are of good quality.

Unless there is a leak from the master cylinder I would leave it alone. With the gearbox in, it is a very fiddly job to do in an

incredibly tight space. It is also a very expensive part which I had to source from Japan (assuming your master cylinder is

the same part# as mine - UK spec type) and you want to reuse the existing hardline.

Edited April 2, 20196 yr by AndrewG

So I got the car up in the air today and made a start on diagnosing the problem. I’d looked at a diagram showing the system and thought that the only two places that could fail had to be the cylinders but my initial look showed no signs of a fluid leak up high near the master cylinder.

After jacking the car up I noticed some fluid around the slave cylinder and flex pipe leading to the slave but not and awful lot. I cleaned up the small amount of mess but there were no obvious leaks. I pressed the clutch in and out and reinvestigated the offending area. Again there was a small amount of fluid gathering on the flex pipe.

 

 

Again I cleaned up the area and this time found a split in the hose. BINGO!!!

 

So it looks like I need a new “hose clutch” (part 17). Has anyone know for this part to fail, do I need to think about replacing any other lines?

A braided line is readily available to replace that,However it may have cost you a master cylinder also.Cylinder bores wear over time and a lip can form inside.The loss of fluid causes the cylinder rubbers to travel past the lip which can flip them rendering it useless.If the fluid rises in the master when its pressed rather than drops its quite ightly its toast i am afraid Chris.Give it a try first and dont be too quick to write off the master when you struggle to bleed the system,And believe me you will it can be a pig !!! I use an Oil can thats soley been used for Brake fluid and back bleed the system from the slave pumping the fluid back through the system with the bleed points open.You will still have to bleed it the conventional way after but it gets the system filled quicker.

Thanks Jim. I have been told about the potential failure of the master cylinder seal but not how to recognise it. :thumbup: And I’ll have a good look around for a braided line.

 

So two sets popped up straight away. If anyone has feedback on either set I’d appreciate knowing it...

 

MLR

 

HEL

Edited April 7, 20196 yr by Chris300

I went for the Hel product, only as I’ve brought Hel products before and have always been happy with the quality the provide.

 

One question I have, do I need to put any fixing tape or agent on the thread at the coupling?

 

One question I have, do I need to put any fixing tape or agent on the thread at the coupling?

 

No, just torque the banjo bolt with the copper washers fitted as shown to the recommended value (FSM page below).

 

 

Edited April 16, 20196 yr by AndrewG

I finally got round to bleeding the clutch today. Unfortunately I had to attempt it by myself which made the job very tricky particularly as the car had been pushed into the garage with little space to work around it. The fluid I got out was very black but is now running nice and clear. However although I’ve now got enough on the clutch to move the car the bite point is very low and I still have around 3inches of slack clutch. I’m hoping that I might be able to get some help tomorrow and finish the job off.

 

Chris you need to kick that clutch pedal like a ginger step son,It will knock the air back to the resovoir quicker.If you still have a small amount of air, a piece of wood holding the pedal down overnight works well.

Chris you need to kick that clutch pedal like a ginger step son,It will knock the air back to the resovoir quicker.If you still have a small amount of air, a piece of wood holding the pedal down overnight works well.

 

Lol. Cheers Jim, I’ll give the little bugger another go tomorrow.

 

Does it matter which nipple I bleed it from now? Also I was unable to bleed from the reservoir nipple as I couldn’t get a spanner to it. Is it worth cutting a spanner down to get to this nipple?

Chris you need to kick that clutch pedal like a ginger step son,It will knock the air back to the resovoir quicker.If you still have a small amount of air, a piece of wood holding the pedal down overnight works well.

 

Jim, you sir are a legend! I left the clutch depressed last night to find that I have full resistance today.

 

Many thanks to everyone for your help. :thumbsup: