Wasn't getting much traction in the convertible section so want to try here too.

I've a '66 vert and I need to re-install the pump for the top. Problem is, I cannot tell what type of fluid is currently in the system.

Whatever it is, it isn't ATF because it's clear so that leaves brake fluid or hydraulic oil. It doesn't have much of a smell to it. I also smeared some on a painted surface and it didn't affect the paint at all. But, I also smeared what I know IS brake fluid on the same surface and it didn't do anything either.

Is there any way to figure out what's in there now?

Thanks,

Dan

By how it smells.
You should be able to tell by the odor because brake fluid and hydraulic fluid both have their own distinct odors.

In the hydraulic system on a 66 Pontiac Catalina ragtop I had, the recommended oil was power steering fluid, which is clear. Maybe that's what you have.

taste it

By how it smells.
You should be able to tell by the odor because brake fluid and hydraulic fluid both have their own distinct odors.
Will have to pick some hydraulic fluid up and put my nose to both.

In the hydraulic system on a 66 Pontiac Catalina ragtop I had, the recommended oil was power steering fluid, which is clear. Maybe that's what you have.
Great, another variable! And I was worried this would be easy.

taste it
Last resort.

After getting the existing fluid on my hands I wiped them off with a white paper towel. Whatever the stuff is, it left traces of green behind on the paper towel.

Dan

Brake fluid, being glycol-based, will mix with water; hydraulic fluid, being petroleum-based, won't.
Pour some of your fluid in a glass and add water. If the two fluids mix, it's brake fluid. If they separate (oil being lighter, it'll go to the top) it's hydraulic fluid.
BillL

I deal with hydraulic oil in our business a lot. Brake fluid will almost give your fingers for lack of a better word a scritchy feeling between your fingers and thumb when you rub them together, and hydraulic oil will be smooth and oily.

Brake fluid has a very distinctive smell, but a small container and compare the two.



Rocky

Brake fluid, being glycol-based, will mix with water, hydraulic fluid, being petroleum-based, won't.
Pour some of your fluid in a glass and add water. If the two fluids mix, it's brake fluid. If they separate (oil being lighter, it'll go to the top) it's hydraulic fluid.
BillL
Perfect, Bill - excellent idea. Thanks!

Thanks to you too Rocky. I'll perform the slip test as well.

Dan

do not use brake fluid for your vert. hydrolic "spelling" oil or atf will do the job.

So I managed to coax some fluid out of the system and into a clear glass. I then also poured some used brake fluid into a second glass. The color and thickness of the two samples looked identical. The sample from the system was a honey color and really didn't have much of a smell to it. The brake fluid, since it was used (bled from another car) was also honey color and didn't have much a smell either.

Then I added water. The sample from the hydraulic system did not mix with the water at all but the sample from the brake fluid container mixed with water instantly.

So then, it's definately not brake fluid in the system. Has to be power steering or hydraulic fluid. Least I know what it isn't!

Dan

Why are you going to all this trouble? Just drain what's is there out and fill it with hydraulic fluid. Power steering fluid or ATF will work fine. Brake fluid will not work because it will foam and it contains water.

Tom

I'm going through all this trouble because there is no way to completely drain the system, and I'd have to run a lot of fluid through it in order to flush the old stuff out completely.

Dan