mandingo214

It appears that I have a brake fluid leak somewhere in the rear, so I pulled the top off the master cylinder, and sure enough the rear was low.

I have no idea if the previous owner used DOT 3, 4 or 5 fluid, and after calling the guy he does not know either. The owner before him is too difficult to contact.

So I took a guess that it was DOT 3, and added a little to the cylinder. It looked like I was mixing oil and water, the DOT 3 staying separate in little bubbles.

I quickly siphoned all the fluid out, and wiped it down.

Is it safe to assume that since the DOT 3 separated that the system has DOT 5 in it?

I may need to bleed it anyway, since I took all the fluid out, but if the pedal is not spongy, will bleeding not be necessary?

In hindsight, it would have been a good idea to siphon and test some of the fluid in a separate container.

Thanks.

MelWff

all the dots mix other than dot 5 so it sounds like that is what you have. Since you lost fluid from somewhere in the rear I would think you could get air in from the same point. You would have to fix the leak and bleed.

mds3013

Your description is exactly how 3 looks when mixed with 5. The 3 ***** up and sinks to the bottom. My old Cartel brand DOT5 was an orange yellow color. My new DOT5 is purple and seems to be the most common color. The fluids smell and feel different also. If you have not totally emptied the MC then there should not be any air from removing fluid. Even if you did but have not pumped the pedal while the MC was empty there should not be any air. Just refill and let any air bubbles rise out of refill holes. The leak could draw in air as MelWff said. Ck. around calipers for fluid they are the most likely to leak. Do you still want pics. of my car with the 225's? I plan to get it out tomorrow. mike...



DOT3 mixed with DOT5

mandingo214

Thanks MelWff and Mike. I put in some DOT 5 and the pedal stayed firm. I stomped on the pedal a few times, drove around being very hard on the brakes, then put the car in the air.

I cannot find a leak. It definitely was not right above the puddle, so now I am thinking the fluid on the floor was from something else, or I just need to let the car sit for awhile in the same place.

Mike, I would still like to see your car with the 225s, if you get the chance.

In case someone looks at this thread in the future wondering if they have DOT 5 or DOT X, here is a procedure I found on another site:

If you need to find out which you have already in the system. Here's how:-

1. Get a dropper (an eye or ear-dropper) and withdraw some fluid from the master cylinder.
2. Put it into a glass jar and then add some clean water to the fluid.
3. Now put the lid on the jar and shake it well.
4. Let it stand for a few minutes.
5. If the water and the fluid have mixed thoroughly and can not be separately identified, then you have regular auto brake fluid.
6. However, if the water and the fluid have not mixed, or have formed blobs or layers, then the fluid is Silicone.