Rep Power: 0

I had a can of ATE type 200 left over from a brake fluid flush, and decided it was a good idea that I should flush the clutch too. I did this according to the service manual, and once I did the clutch had zero pressure in it and kept going straight to the floor. Checked for leaks and saw that the slave was leaking from the boot so I assumed the seals were bad. Went and picked up replacement from Advance Auto, which when placed in also started leaking from the exactly same place. Took it back and the 2nd replacement went in fine and started getting pressure back into clutch and then the Clutch Master Cylinder started leaking. So once again bought a replacement for the CMC got it in, started bleeding the system again and now the new slave is also leaking again from the boot... Am I an idiot for assuming that since the cap on the reservoir said DOT3/DOT4 I could use the ATE type 200? I'm at a loss for why I can't get this to work.....
Sorry, I forgot to mention this is on a 2005 Civic EX Special Edition D17A2 Manual 5 speed pretty much all OEM parts.

 
Rep Power: 517

DOT4 brake fluid should be no problem, it is still normal brake fluid that just has a higher boiling point than DOT3.

I don't know first-hand anything about the actual fluid you have in front of you, other than what I just saw on a website. (It is compatible with and will mix well with most DOT3, DOT4 or DOT 5.1 fluids...?)

Could your fluid be contaminated?
Got kids?

Old rule of thumb is to never use used brake fluid.
If the can has been sitting around after being opened, just toss it out and buy fresh. Fresh fluid is cheap..... And IMO you sure don't need racing brake fluid in your clutch.

 
Rep Power: 0

I agree that it's not necessary for a clutch. I had an extra liter that was un-opened purchased a month ago which I just opened/unsealed for this flush. Aside from the possibility that against all odds I received two bad slave cylinders (purchased new), the only thing I can think of is the brake fluid.

 
Rep Power: 0

I was wondering if the borate-esters they dope into the DOT4 to make the higher boiling points are eating away at the seal inside the cylinder in the slave. I mean it can't be the brake fluid itself (just glycol ether just like DOT3....)

 
Rep Power: 517

I can't picture that being an immediate effect. IMO that would take place over a much longer period of time. Days/weeks/months/years instead of seconds and minutes.

And I suspect the same things would have happened to your brake system if the fluid were the actual cause of the clutch hydraulic parts failing.

But what do I know? I'm not an engineer or a professional failure analyst.

I CAN tell you there was a recall on some Odyssey master cylinders where a seal was replaced that was supposedly affected by non-approved brake fluid......so IDK....but I guess anything is possible.
Found this on a justanswer, quoted from the service info:
The following is quoted from Honda's Service Bulletin 10-069 regarding this problem...

"A cup seal in the master cylinder is sensitive to the type










I have no idea if this could apply to a clutch hydraulic system though.
Do-over, and use the factory recommended fluid this time?

Aftermarket.......?


Do you know what NEW stands for?


Never
Ever
Worked

 
Rep Power: 0

Fair enough, that is an entirely valid point, I guess I meant "unused." As far as the brand of the clutch slaves, the first one came in a box labeled with the perfection parts brand but was a Nissin slave cylinder identical to the original one I pulled out of my car (or at least the one I pulled out, not sure what the OEM part is). The second slave was branded FTE but looked like it could have been a re-branded Nissin slave as well.

 
Rep Power: 0

Just FYI, I ultimately just took my car to a garage I trust and they suspect it was the fluid causing all the seals to leak in the hydraulic clutch. It cost me an arm and a leg, so if in doubt just stick with DOT 3.

 
Rep Power: 209

I flushed the brakes and clutch with DOT4 about two years ago and have not had any problems.

 
Rep Power: 203

Leaking seals in a hydraulic system is usually a sign of oil contamination.

 
Rep Power: 517

^^Not always, but swollen seals definitely would be an indicator of (petroleum) contamination.
The rubber seal on the cap and the rubber thingy that sticks into the clutch fluid reservoir would be the first things to show evidence IMO.

OP said this can of fluid was sealed though. Maybe just incompatible fluid? At least it's over now....