clutch fluid replacement

jliu

Has anyone use a vacuum type device to bleed clutch fluid in our Zs'. The reason I ask is because I have a Mityvac that uses a compressor that I have used to bleed brakes and clutches fluids in other cars. It worked great.

gomer_110

FSM says specifically NOT to use a vacuum or power assist device at all.

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'17 Titan Bone Stock

JARblue

Do NOT use a vacuum assisted device on the clutch system.

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jliu

Got it.
But anyone know why that is?

JARblue

Mostly likely it has to do with the horribly shitty internal seals on the master and slave cylinders. That warning is probably the best acknowledgement we'll ever get from Nissan on the matter.

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runwhatyabrng

First time I see this. I flushed my clutch using a vacuum bleeder , all kinds of crap came out. No problem so far, did it on my brother's G35 also, same thing no problem

Manual actually says:
NOTE:
Do not use a vacuum assist or any other type of power bleeder on this system. Use of vacuum assist or power
bleeder will not purge all the air from the system.


I was not purging air but flushing out the old fluid for new fluid

jliu

So you just vacuum fluid out of the bleeder nipple and it worked?

runwhatyabrng

Same process as the brakes, I usually empty out the reservoir first and put fresh RBF600 in there then I add my top up bottle to the reservoir to prevent running it dry. (pics of brake bleeding below)

Attached Images

	brake bleeder.jpg (132.6 KB, 84 views)
	top bottle.jpg (129.6 KB, 85 views)

jliu

Thanks.

JARblue

I expect the main reason the manual states not to use vacuum or pressure bleeding is because the seals in the master and slave cylinders are so shitty and prone to failure. If you keep the vacuum/pressure very low, I would be it works just fine for flushing fluid. But too much pressure will probably mess up the seals and allow air into the system and fluid to escape past the seals.

If you do a CSC delete kit and SS clutch line and HD CMC kit, then you pretty much replace everything in the clutch hydraulic system except for one longer hardline. Very easy to blow out with compressed air during the install. With only the OEM master left, I still saw lots of contaminants in the system on a regular basis. I had to flush clutch fluid twice a year at least because of this.

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runwhatyabrng

The Vacuum tool that I use (Mityvac knockoff) does not apply any pressure to the system (unlike the Motive system) I would say that the seals would have to be really bad and would not handle the pressure of pressing down on the clutch if they could not handle a small amount of suction put on the bleeder screw. Specs for the unit are Vacuum @ 90 psi(6.2 bar): 26 in. Hg (88 kP or -1.9259414420980008 psi relative to atmosphere

JARblue

Your vacuum tool still applies pressure. It just happens to be negative pressure instead of positive pressure. Either way, I think the key is not to apply too much in either direction. The -1.9 relative PSI your vacuum tool applies seems very low and unlikely to harm the seals. Power bleeders are often pumped to 10-15 PSI, and I would bet that 5 PSI could compromise internal seals in the system. I'm not sure you could use a power bleeder at a low enough PSI and still be effective.

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TBatt

I have been using a vacuum bleeder for years and have used it on my Z for the brakes and clutch. This is the bleeder that I have. https://www.griotsgarage.com/product...fType=&from=fn

As JARblue stated, this creates a negative pressure differential. Not a lot but more than enough to suck the fluid through the system. You can watch bubbles, crap and the color of the fluid change as it works.

For bleeding this how I use the pump. First and foremost fill the reservoir and check it often during the bleed unless you have a replenish bottle which I highly recommend. Place a boxed end wrench over the bleed nipple and then attach the pump hose. Open the bleeder and let the pump start to work (keep it pumped up). After you see fluid start to flow slowly pump the brake or clutch pedal using slow full strokes. This will push the fluid through the system a little faster to help push the air out. When you see nothing but clear fluid with no bubbles close the bleeder. Top off the reservoir and move to the next brake. I've done this many many times by myself and it works great.

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jliu

I just flushed out my clutch fluid. I have a 2014 with 11k miles. I had previously changed out the clutch fluid in the reservoir only. I used a Mityvac vacuum system to extract the fluid out. Only small amount of "slightly brown" fluid came out initially. I went through three rounds of fluid in the reservoir. Everything shifted fine and all is good. I did this along with an oil change, tranny fluid and differential fluid change.