Mixed Brake Fluid
Thread Starter
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Outstanding HDF Member
Joined: Oct 2006
Posts: 2,183
Likes: 1
From: Lenexa, KS (KC)
Mixed Brake Fluid
Manual says to use DOT 5, and I wasn't paying attention to what I had in the master cylinder -- it is amber in color, which I assume is DOT 4. Poured about an ounce of DOT 5 in the master cylinder before realizing what I was doing. 
What now? Will bleeding very well and refilling with DOT 4 be okay?
What now? Will bleeding very well and refilling with DOT 4 be okay?
Cruiser
Joined: Feb 2010
Posts: 236
Likes: 0
i think your going to shat yourself this is what i found on another site
Hi.
DOT 5 is silicon based, and DOT 4 is water soluble oil based. The two are not compatible, nor can they be mixed. They will react, and swell all the rubber parts to the point they will lock it up solid.
GET THAT CALIPER OFF THE BIKE!!!!
You need to have it overhauled so you can use the DOT 4, because you can not get the fluid out of the seals, and they can swell and lock up the caliper.
I also recommend you replace the front brake lines(The rubber parts) now that they have been contaminated with the wrong fluid.
__________________
Hi.
DOT 5 is silicon based, and DOT 4 is water soluble oil based. The two are not compatible, nor can they be mixed. They will react, and swell all the rubber parts to the point they will lock it up solid.
GET THAT CALIPER OFF THE BIKE!!!!
You need to have it overhauled so you can use the DOT 4, because you can not get the fluid out of the seals, and they can swell and lock up the caliper.
I also recommend you replace the front brake lines(The rubber parts) now that they have been contaminated with the wrong fluid.
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Tourer
Joined: Feb 2008
Posts: 473
Likes: 0
From: The Peach State!
What fluid is called for on the m/c cover? That's what you need to run. If it's dot 4 run dot4. Either way you need to suction the master cylinder dry and fully bleed the proper fluid into the system. I'd get that mix out asap!
Tourer
Joined: Feb 2008
Posts: 473
Likes: 0
From: The Peach State!
i think your going to shat yourself this is what i found on another site
Hi.
DOT 5 is silicon based, and DOT 4 is water soluble oil based. The two are not compatible, nor can they be mixed. They will react, and swell all the rubber parts to the point they will lock it up solid.
GET THAT CALIPER OFF THE BIKE!!!!
You need to have it overhauled so you can use the DOT 4, because you can not get the fluid out of the seals, and they can swell and lock up the caliper.
I also recommend you replace the front brake lines(The rubber parts) now that they have been contaminated with the wrong fluid.
__________________
Hi.
DOT 5 is silicon based, and DOT 4 is water soluble oil based. The two are not compatible, nor can they be mixed. They will react, and swell all the rubber parts to the point they will lock it up solid.
GET THAT CALIPER OFF THE BIKE!!!!
You need to have it overhauled so you can use the DOT 4, because you can not get the fluid out of the seals, and they can swell and lock up the caliper.
I also recommend you replace the front brake lines(The rubber parts) now that they have been contaminated with the wrong fluid.
__________________
Road Master
Joined: May 2007
Posts: 899
Likes: 10
>>What now? Will bleeding very well and refilling with DOT 4 be okay?<<
If this just happened you won't have to rebuild anything. But you need to remove the master cylinder, the brake line, and the caliber from the bike and also disassemble the caliber right now. Then wash and flush everything in denatured alcohol. (The caliber needs to be taken apart as just flushing won't get all the mixed brake fluid out.)
Then no matter what the master cylinder says on it you can run DOT 4 or 5 as long as you don't mix the two. So it's not a big deal as long as you don't leave it in there long enough to gel . . .
If this just happened you won't have to rebuild anything. But you need to remove the master cylinder, the brake line, and the caliber from the bike and also disassemble the caliber right now. Then wash and flush everything in denatured alcohol. (The caliber needs to be taken apart as just flushing won't get all the mixed brake fluid out.)
Then no matter what the master cylinder says on it you can run DOT 4 or 5 as long as you don't mix the two. So it's not a big deal as long as you don't leave it in there long enough to gel . . .
Cruiser
Joined: Jul 2009
Posts: 148
Likes: 0
No need to panic and start removing and changing all the parts. Yes DOT 4 and 5 do not mix. Unless you have had them mixed for a long time there is no need to change and replace everything. Flush the brake system real good and then put in the right fluid and bleed it until all the air is out. It is easiest to bleed the system by forcing fluid from the caliper up into the master cylinder using a large plastic syringe and a piece of tubing attached to the bleeder valve. This will get the most air out the fastest. Then finish the bleeding job by the most common method of pumping the master cylinder and opening the bleeder valve.
Road Captain
Joined: Oct 2007
Posts: 715
Likes: 2
From: NW Florida
Have you ever changed the fluids out before? If your manual calls for Dot 5 that's most likely what's in there already. Like stated above Dot 4 & 5 don't mix so if you haven't pumped the breaks no problem. Just suck everything out of the master cylinder NOW
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Thread Starter
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Outstanding HDF Member
Joined: Oct 2006
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From: Lenexa, KS (KC)
Haven't pumped the brakes, so everything should still me in the Master Cylinder. I'll suck out the mix and then flush good with dot 4. Thanks.
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Tourer
Joined: Apr 2008
Posts: 404
Likes: 1
From: Athens, Georgia
I would pobably go to Auto Zone, PepBoys whatever and buy a Mity Vac, I just got one for $29.00. You can "suck" all of the fluids out fairly easy and it makes re-filling-bleading a breeze. Like some other guys have said you should not have to take anything apart if you will do this in a reasonable amount of time.
Road Master
Joined: Mar 2008
Posts: 757
Likes: 1
From: Ontario, Canada
Are you 100% sure that DOT 4 was in it????? All brake fluid gets golden after a while... called dirty.