Andy Hedin

I'm thinking about purchasing either a MityVac one-man brake bleeding pump or a different one offered by Griot's Garage (looks like a bicycle pump with a huge reservoir). I'm not happy with the clutch pedal feel in my A4 with ATE SuperBlue fluid (it's been in there since last August) plus my clutch is starting to squeak. Long story short, I believe the fluid may be the cause and I'd like to swap it out for some Valvoline SynPower DOT 4 brake fluid I picked up.

I've never bled my brakes before but I do consider myself mechanically inclined.

Here are my questions:

1) I've read tons of posts in the archives and it sounds like the ABS system needs to be "pulsed" via the VAG tool in order to flush the fluid out of the ABS unit. How important is this? I don't have access to the VAG tool so this won't be possible. Will I damage the ABS system if I don't flush the fluid out of the unit?

2) I've read that the clutch master cylinder shares the fluid with the brake system. I've also read that you should bleed the clutch master cylinder when you bleed the brakes. Is this true? Is there a bleeding nipple on the transmission housing for this? Does it look just like one of the brake caliper nipples?

I'd appreciate any and all comments.

Thanks much,<p><a href="mailto:andy_hedin@hotmail.com"><img SRC="http://pictureposter.audiworld.com/AudiWorldPics/2000/A_Hedin_Sig.jpg" BORDER=0></a>

TM

Andy, long time....

I am not an expert on these matters, but IMHO, you do not need to pulse the ABS nor do you need to bleed the clutch cylinder to bleed the brakes.

The Mityvac is well regarded by some quattro listers, I was thinking about getting one as well.

Why do you think the fluid is causing clutch squeak? Have you checked to see if the pedal arm needs lube?

BTW, I don't think the Valvoline stuff is better than Super Blue- I'd go with either the Motul 550/600 or Castrol racing fluid if you want stuff that's even higher performance than the ATE stuff, although all of it is overkill.

A year is a good fluid change interval, however, so you might as well do it.

Regards,
TM

Audiboy

The mighty vac is good as we used it in the shop a while back, but failure to use it properly can add bubbles to your system. It is so much easier to have someone pump your brakes 4 times, hold it down, and bleed the fluid out. Farthest wheel going to the closest.

Do you have to bleed your clutch? Yes, if you are replacing the fluid, because that will be the only way to drain it out. But don't worry about bubbles in your clutch as they won't propagate to the brake or vice versa as they are only sharing a reservoir. No need to pulse the ABS, but I recommend to run your car while bleeding to get the benefit of the brake booster unless the person pumping has strong thighs and calves ;-) Good luck.

BTW, I love Motul 5.1

Andy Hedin

<i>I am not an expert on these matters, but IMHO, you do not need to pulse the ABS nor do you need to bleed the clutch cylinder to bleed the brakes.</i>

Based on some responses I've gotten, I don't think I'll worry too much about the ABS system. I will take a look at the trans housing for a bleeding nipple. If I can find it, I'll bleed it...if not, I'm not going to worry about it too much.

<i>Why do you think the fluid is causing clutch squeak? Have you checked to see if the pedal arm needs lube?</i>

At least one other guy on the A4 Forum had the exact same symptoms that my A4 has (squeaky clutch pedal, difficulty modulating clutch, "sticky" clutch feel). I've been thinking that it was my clutch on it's way out. But we both noticed the same problem since installing the ATE SuperBlue fluid. Also, there are some folks who feel that the SuperBlue has caused their master cylinders to die an early death.

<i>BTW, I don't think the Valvoline stuff is better than Super Blue- I'd go with either the Motul 550/600 or Castrol racing fluid if you want stuff that's even higher performance than the ATE stuff, although all of it is overkill.</i>

Yup, I know it's not better than the SuperBlue...but the specs are good enough for the type of driving that my A4 sees ("spirited" street driving). Here's some specs I had been gathering:

<b>Castrol SRF (Special Racing Fluid)</b>
DOT Rating of 4
518° Wet Boiling Temperature
590° Dry Boiling Temperature
Is Compatible With Other Fluids
33.8 oz

<b>Castrol LMA</b>
Dot Rating of 4
311° Wet Boiling Temperature
446° Dry Boiling Temperature
Is Compatible With Other Fluids
12.0 oz

<b>ATE Super Blue</b>
Dot Rating of 4
382° Wet Boiling Temperature
536° Dry Boiling Temperature
Is Compatible With Other Fluids
1 liter

<b>Valvoline SynPower</b>
Dot Rating of 4
333° Wet Boiling Temperature
513° Dry Boiling Temperature
Is Compatible With Other Fluids
12 oz or 32 oz bottle

<i>A year is a good fluid change interval, however, so you might as well do it.</i>

I agree...I think I'll be picking up a MityVac.

Thanks for your feedback.<p><a href="mailto:andy_hedin@hotmail.com"><img SRC="http://pictureposter.audiworld.com/AudiWorldPics/2000/A_Hedin_Sig.jpg" BORDER=0></a>

CP

<p>Cy...Pearl '97 1.8TQMS, APRv3, Neuspeed, H&R Sport, Neuspeed/Bilstein, AEZ Bimos, Yoko AVS Sports, ATE Powerdisc, Mintex, Valvoline SynPower, Autometer, K&N, Air Box Mod, Clears, PIAA, Alpine, Red Domes and Readings, Sport Grill, Aluminum Trim,

Ray Calvo

I initially used the buddy system for brake bleed - one guy pump pedal and then hold it down while second opens bleed screw. Went thru two master cylinders on Porsche 911 in two years. This method pushes the brake piston seals past their normal wear positions, and prematurely wears them out. if you open up a used master cylinder, you will see wear marks where the piston and seals normally travel. Bleeding brakes in this fashion forces the pistons past this normal wear area, and over a little wear lip. This damages the rubber piston seals.

I then switched to a hand vacuuum pump (Mity- vac??). Got lousy results.

I have since switched to an air tank pressurized to 30 psi. I bought an extra brake reservoir cap and cut a hole in it to mount a screw-in tire valve. I now pressurize the brake system and proceed to bleed the brake calipers. Worked great on old Audi Coupe Quattro and '76 and '84 Porsche 911, works fine on '95 Porsche 993. Haven't had need to bleed the A4 brakes yet. Never pulsed the ABS on the Coupe, and don't do it on 993 - no problems.

Clutch bleeding not a bad idea, but probably only has to be done every couple of years. Never did it on any car (and Coupe went 126K on OE clutch), but want to do the 993.

Geza

I spoke to a mechanic from Fred Baker Audi at the Mid Ohio track event this week regarding the squeaky clutch pedal (mine got squeaky after I changed to super blue fluid). He said that the clutch master cylinder shaft (protected by a rubber boot) needs to be lubricated with a spray on type grease.

This kind of makes sense, because when I change my brake fluid, I didn't bleed the old fluid out of the clutch hydaulic circuit - it should still have the factory fluid in it.

KKelly

It was like $35...just can't recall the name. The only thing is you need to get a longer hose for it. Most guys change the hose on occassion anyway. I have seen it advertised in the mags, starts with an M. You can make one cheaper but it does have an installed pressure gauge and it is still pretty cheap. I use it on my car all the time.

The Ultimate Garage also makes the ultimate deluxe version but it isn't cheap. I have a friend with it and it is real nice. For example, when working on calipers or changing lines you can just put the cap on (it has a quick disconnect from the hose) to create a vacum so the fluid won't leak. Check it out..

http://www.ultimategarage.com/special1.html