J.Yo

Anyone have any thoughts on why the fluid gets so dark so quickly in our cars? The only sources I can think of would be moisture, heat, and contamination.

Moisture - I just bought some of the OEM fluid today, so I'm going to leave a small amount in an open container to see if ambient moisture is causing the color shift. If so, that means our seals are not very good. I kinda doubt it though.

Heat - if it's heat, our clutch must be putting out a lot of heat to be turning brake fluid dark so quickly. I have 1400 miles on my car (1.5 months old) and the fluid is already looking like iced tea.

Contamination - are there seals or bellows on the moving parts for the slave cylinder? Perhaps the dust from the clutch is getting on a sliding surface and being pulled into the system with each actuation. Forgive my ignorance, in that I am not familiar with how our slave cylinder works. I noticed that the vette slave cylinder does not look like slave cylinders on other cars that I haved owned. In my other cars, the slave cylinder would be external to the transmission housing and actuate an arm that engaged the clutch.

I'm just curious if anyone has determined the cause for all this headache.

Maui

What is the advantage to doing this? Just curious.

Hoonose

It helps avoid the dreaded 'clutch stuck to floor' problem.
It also helps smooth out the clutch engagement action.

I originally did it as skeptic, but was quite surprised in the improvement. I now do it every few months.

Ranger

J.Yo and Maui, here is the answer: Taking Care of Your Clutch

Ranger

'06 Quicksilver Z06

If it was that nasty, depending upon how often he drives it, I wouldn't even give it that long.

I'd take a look at it a couple days later and change it a couple days later. I'd pump that clutch pedal 10 or 20 times like he said to bring up all of the old clutch fluid still in the line

Brake fluid is cheap. I try to change mine about every week. Pretty much whenever I wash the car. The longest I have gone is about 3 weeks. I don't particularly care for the bulb turkey baster. Less control and a good chance to wind up eith brake fluid on your paint. Get a syringe that you can draw back the plunger on to draw it out.

I use a 60cc syringe and just draw it out with the syringe. Then draw up about another 60cc of new fluid and put it into the reservoir after cleaning the cap. Then pump the pedal. Takes less than 10 minutes.

By now, all of the clutch fluid in my line looks damn near brand new.

2LT-Z51

thank you for all your knowledge on this and many other subjects...

yours was, by far, the most informative and until it happened to me it was just in the back of my mind.... i could not remember your name at the time of this post.... please accept my apologies....

this place is great!!! so much info it makes my head spin at time... my tires too!!!!!

drdsouz9

Guyz please HELP.

So I was trying to flush the Clutch Fluid yesterday and when I went to Power Chevy in Irvine the guys at the service counter said that the the GM Part number in my Owner's manual was discontinued. In the owner's manual it calls out GM Part No. US 88958860.

He gave me a 16 ounce bottle of Hydraulics Clutch Fluid #12345347. Now this bottle is clearly marked clutch fluid and in the back it is marked 'DOT3 with friction modifiers'.

No one carries the old GM part number and on the forums, everyone seems to be using Prestone DOT-3 brake fluid. What is the deal here. Can I use the Fluid that was given to me by the Power Chevy dude?

drdsouz9

http://paceperformance.com/index.asp...D&ProdID=91000

I just found this link. It says Super Dot-4. That is what is in the original manual. I think the guy gave me the wrong stuff. I put this into the reservoir. Should I get it out and then replace it with the Prestone Super Dot-4? Where do you get this stuff?

Ranger

What car are you talking about. You didn't include it in your post and your profile is vacant.

I'll assume it's a C6, the Chevy spec for the the C6 clutch fluid is GM-branded Super DOT4 brake and clutch fluid. DOT3 they gave you is spec for C5s. Wouldn't put that in the C6.

So that parts guy is incorrect. Suggest trying a diff dealer. The GM Super DOT4 is made by Petosin and it's a very good fluid.

I'm using Prestone DOT4 Synthetic. Widely avail. But others would be fine too.

Here is a list of alternatives. Company that compiled the list doesn't sell brake fluid.

Ranger

Modshack

Contamination would seem to be the issue. I do not have my Vette yet, so maybe someone can confirm my ideas. It the slave cylinder is indeed internal (in the bell housing) then this is the reason. On the Audi's I am familiar with the slave is a round cylinder that fits over the input shaft and works directly on the integrated throw-out bearing. In a design like this, the slave would be exposed to clutch dust, picking it up past the seals and eventually darkening and corrupting the fluid. Other than seal deterioration, I don't see where else the discoloration can be coming from. In the Audi's, when the slave fails, the pedal drops to the floor and They do use a common brake reservoir for fluid, but I've never experienced this darkening of the fluid. Once again, I'm speculating on the design here, but it would seem a valid conclusion if, in fact, the actual slave is inside the bell housing...

KMK454

So... um... I've never done this in 56k miles of driving my C6... should I be worried?

Ranger

Clutch actuator (slave) is inside the Bellhousing exposed to temps that exceed 400 degrees during launch or sequential high-rpm shifts. Such temps cause rapid deterioration of the fluid. The tell is discoloration. Black fluid has a very low boiling point and the highest incidence of pedal woes.

Ranger

Ranger

No, you probably don't drive the car aggressively, do launches or repetitive high-rpm shifts. It's those actions that create the high temperatures that make blackened (deteriorated) clutch fluid literally boil, triggering pedal misbehavior.

But if the clutch fluid is black it ought to be cleaned up. So the guy you lend your car to that lacks your sense of self-restraint won't get pedal woes either when, out of ear shot, he hammers your car to redline through the gears.

Ranger

Zig

just wondering...

i wonder what it would take to test the 'darkened' fluid boiling point. would it be possible to use the same method one would use to test a therm.?

Vet

I flushed my clutch fluid reservior the other day using an entire 8.45 ounce bottle of GM Super DOT-4. Pumped the pedal a good 10 - 15 times between each fluid extraction. Fluid was originally black, became quite clear after the 8.45 ounce flush... not perfectly clear, but about 85% clear.

After about 100 miles, while not even thinking about it, I seemed to notice that my clutch pedal felt a bit "stiffer". Almost felt as if the pedal action was a tad higher, had a more firm solid feel. At first I was wondering why this would be, then I remembered that I had changed the clutch fluid!... so I don't think I was just imagining it. The difference isn't huge, but it is noticeable... and it's indeed an improvement.

After flushing in the 8.45 ounce of GM fluid, I took an 825 mile trip. Just returned yesterday and looked at the fluid... looks black again. So I plan to flush in one more 8.45 ounce bottle of Super DOT-4 and call it a season. I think at that point, especially since I do not drag race, the clutch system should be ok at least for another 6 months or so. The 825 mile trip should have circulated some of the remaining old fluid in the slave to the reservior so that I can flush the "rest" of it out today with the second bottle of DOT-4.

Will probably get on a schedule of flushing in two bottles of Super DOT-4 every spring and fall. This may not be an adequate schedule / procedure for those who drag race, but I'd think it would be fine for daily driver people who want their cars to run tip-top with minimal tinkering.

Ranger

^^^ Very good approach, Vet.

Ranger

C8-Vette

After about 4 or 5 bottles of 12 oz. DOT 4 mine stayed clear for the past 3 months.

Modshack

Pardon my ignoranse (I don't have my '08 yet) but shouldn't there be a Bleed screw for the system down by the bellhousing somewhere? Other cars of similar design have this. That would certainly avoid using the large quantities of fluid it seems to take to clear the system..

Ranger

The design common to the LS1/2/6/7 motors puts the (clutch hydraulics) bleed screw at the end of a blind reach with scant maneuver room for the tool. PITA. Also full bleed requires a lift. So owners install a remote bleeder that makes the job of a full bleed much easiler. That install is often done when the clutch and assoc hydraulics are changed out.

So the easy and accessible path is to keep the fluid clean via the reservoir.

I paid a shop for a full bleed....around $120 in 2001. That cost is what prompted me to focus on the reservoir path.

Ranger

70454

This is exactly what mine looked like at 13K miles. I also noticed some difficulty with the pedal/shifting. Thanks for the great write-up.