change the brake fluid?

   / change the brake fluid? #1  

Doc_Bob

Elite Member
Joined
Mar 17, 2006
Messages
3,059
Location
Wisconsin
Tractor
2003 NH TN70A
I have changed every fluid and filter on my used New Holland TN70A. The tractor is a 2003 model and when I bought it, had 168 hours on it. The only fluid I have not changed it the brake fluid. I am told that it is a mineral oil and not a DOT3 or DOT 4 fluid. I looked in my owner’s manual and it does not say. I called www.messicks.com and bought 2 quarts of NH Ambra spec fluid from them.

Does anyone change their brake fluid? Does mineral oil brake fluid need replacing? Does it absorb water like car DOT3/4 fluid? Am I wasting my time? My money?

Bob
 
   / change the brake fluid? #2  
Mineral oil is not hygroscopic, so you are wasting money in my opinion...
Dusty
 
   / change the brake fluid? #3  
My VW uses mineral oil for something, perhaps powersteering. I know it isn't brake fluid. Then again, tractor brakes are not likely to get as hot as those on a car. I never heard of hydraulically activated brake systems on a tractor, but then again, yours is a lot bigger than any tractor I've owned. Are the brakes themselves dry or wet?
 
   / change the brake fluid? #4  
Doc,

I guess I would look at the tractor break fuild as I would in my car. I have never changed it untill I was bleeding the system due to a wheel/master cylinder change. If you do deside to change/flush, consider it quality time with the wife yelling "down....closed....up ....open ect. So much fun
 
   / change the brake fluid? #5  
If you change the brake fluid in your automobile every other year, you probably won't ever have a hydraulic brake failure of the cylinders or the lines. Usually brake lines rust out from the inside before they rust through from the outside.
Dusty
 
   / change the brake fluid? #6  
I change the brake fluid every other year on my automobiles. It is amazing what kind of junk comes out. You don't need to use your wife for this, it is way better to buy a vacuum system like the mity-vac where you actually suck fluid from the bleeders. All you need to worry about is keeping the reservoir full so as not to suck air into the system, including the ABS valving, which would create all sorts of problems. I usually flush about 6 pints through the system before the new fluid is nice and clear.

The old fluid is dark and water fouled with a much lower boiling point (aka early brake fade) than the new fluid. Plus, the water will not be in the system to corrode it.
 
   / change the brake fluid? #7  
Here is some interesting reading about brake fluid. I am considering DOT5 when I do the next complete brake overhaul on my car.
Dusty
 
   / change the brake fluid? #8  
Don't do the DOT 5 thing.

The water which is inevitable will then settle into pockets within the braking system and corrode. Also these pockets of water will burst into steam at the boiling temp of water while even plain dot3/4 will make it well into the 400s. Air and steam in the brake fluid will compress instead of stopping your truck.

Then there is the situation where you have a leaky wheel cylinder on a long trip and need to pick up a pint of fluid to top up the system. Not many gas stations carry DOT5.

A quote from the reference you posted.

"If you have already changed to DOT 5, don't compound your initial mistake and change back."

I would take their advice and stick to the dot 4 just like the manufacturer of your truck did.
 
   / change the brake fluid? #9  
I don't know anything about the brakes on my tractor. Spec sheet says 'wet type, disk'. So I'm assuming it has brake fluid. But there is nothing in the manual that says anything about inspecting or changing brake fluid.

Off topic question, where in the heck is/are the brake disk(s)?
 
   / change the brake fluid? #10  
When they say "wet type" they mean that the brakes are immersed in the oil of the sump of the trans. Just like the clutch on a non-harley motorcycle. From what I have seen, the brakes themselves are in the final housings just inside the wheels on the rear axle only. No front brakes, but manual application of mechanical brakes. There is a friction material but the life expectancy is very high.
 
 
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