Brake Fluid Change and Clutch Fluid

[White987S]

When the brake fluid is changed on the 987 and 987S (every 2 years) is the clutch fluid change at the same time? Do they share the same fluid? Or are they separate systems and reservoirs? Thanks.

[Loren]

When the brake fluid is changed on the 987 and 987S (every 2 years) is the clutch fluid change at the same time? Do they share the same fluid? Or are they separate systems and reservoirs? Thanks.

Yes. Yes. No.

[White987S]

When the brake fluid is changed on the 987 and 987S (every 2 years) is the clutch fluid change at the same time? Do they share the same fluid? Or are they separate systems and reservoirs? Thanks.

Yes. Yes. No.

THANKS, Loren! That's what I thought. I had a dealership (Westmont, IL Porsche) tell me today that they were seperate systems. It is so frustrating when the dealership tells you wrong info...or when you know more than they do!

[Porschelibrarian]

When the brake fluid is changed on the 987 and 987S (every 2 years) is the clutch fluid change at the same time? Do they share the same fluid? Or are they separate systems and reservoirs? Thanks.

Yes. Yes. No.

THANKS, Loren! That's what I thought. I had a dealership (Westmont, IL Porsche) tell me today that they were seperate systems. It is so frustrating when the dealership tells you wrong info...or when you know more than they do!

If you need the workshop manual for the 987 ( The new revised version has grown to about 3,500 pages from the "Basic Workshop" manuals I had last year ) let me know.

[white]

Anyone knows the amount of brake fluid that needs to be flushed for both the Manual and the Tiptronic Boxsters? What the manual states is that the car needs only 0.39L for the brake fluid. Then how about the Clutch? Does the Tiptronic works the same as the Manual ones? Thanks.

[RFM]

A brake fluid change, inclusive clutch, will take approx. 1 litre of fluid. Tiptronic and manual use the same BRAKE system with a "few drops less" fluid contents for the Tiptronic because absence of clutch.

[jim_hoyland]

Is there a DOT preference for 3 or 4 ?

[JFP in PA]

4 is preferred for these for the cars as it has a higher boiling point.

[jim_hoyland]

Today I had the brake fluid flushed and new DOT4 added.

I had the shop save me a 1/2 pint sample of both the old fluid and the new fluid.

I am in the process of testing both samples; will post pics and data…

[JFP in PA]

1 hour ago, jim_hoyland said:

Today I had the brake fluid flushed and new DOT4 added.

I had the shop save me a 1/2 pint sample of both the old fluid and the new fluid.

I am in the process of testing both samples; will post pics and data…

For future reference, OTC makes a digital electronic brake fluid moisture test tool that costs about $20 and is as accurate as a $800 lab testing tool, and can actually test the fluid while it is still in the system master cylinder 😉

[Silver_TT]

+ 1 to JFP's suggestion about the OTC pen tester

[JFP in PA]

[jim_hoyland]

I used a two prong tester similiar to the one pictured. I fist tested fluid from an unopened container then tested my 2-3 year old fluid from the Boxster. Results were nearly identical. See

[jim_hoyland]

I my local shop said the best test are Test Strips. I dipped each into new and old fluid, waited for the strip to turn color and found the new fluid registered a slightly lower moisture content. The left end of the strip is for brake fluid; the right end for coolent. I did not test coolent yet

[Silver_TT]

I have no experience with the electronic brake fluid tester in your picture, only the OTC pen tester, so I cannot opine except the following.  The fact that it's saying 1.5% moisture content for brand new fluid -- it either isn't very accurate (most likely) or the new fluid you bought is contaminated with moisture.  I see they have different colors in your measuring strips but I don't know what % that translates to.  New fluid should not have high moisture content, this is the whole point of replacing the fluid to get the moisture content down.

[JFP in PA]

1 hour ago, Silver_TT said:

I have no experience with the electronic brake fluid tester in your picture, only the OTC pen tester, so I cannot opine except the following.  The fact that it's saying 1.5% moisture content for brand new fluid -- it either isn't very accurate (most likely) or the new fluid you bought is contaminated with moisture.  I see they have different colors in your measuring strips but I don't know what % that translates to.  New fluid should not have high moisture content, this is the whole point of replacing the fluid to get the moisture content down.

 

Silver_TT has a valid point, a fresh container of Dot 4 fluid should read zero moisture, not 1.5%.  We tried the test strips once, found them to be very misleading and very often inaccurate.  One of the main advantages of the digital tester, besides dead on accuracy, is that you can test the fluid while it is still in your car.  While that sounds more convenient than useful, using the digital tester on customer cars, we have found that for some owners, we don't need to change the fluid as often, sometimes 4-5 years between flushes, and without any concern.  That alone can be a substantial cost savings to the owner.  And we also test every container of Dot 4 fluid when we open them, if any are above zero, they get sent back and replaced with fresh containers that test properly.

 

So if you haven't done so, do not use your new fluid, that moisture level is already nearly out of spec; and if you have used it, get some fresh Dot 4, test it, and then reflush the vehicle.

[jim_hoyland]

Great feedback. Interesting point about your own testing of new brake fluid.

I’ll stop by Autozone and see what the say.

[JFP in PA]

8 minutes ago, jim_hoyland said:

Great feedback. Interesting point about your own testing of new brake fluid.

I’ll stop by Autozone and see what the say.

 

When you buy brake fluid, you typically have no idea how old it is, or how it has been stored.  A properly sealed container should be a zero for fairly extended period, but because Dot 4 is so hydroscopic, and some containers, particularly plastic ones, are moisture permeable and can suck up moisture sitting on the shelf.  That is exactly why we test them.