I'm planning a complete brake job replacing the front pads and rotors and rear shoes and drums including wheel cylinders. My ride is a '90 F150 4.9 l with 4-speed transmission. I've had the truck for about 15 years and have not changed the brake fluid; It is almost black; so I figure I'll drain the lines and replace the fluid, too. I've read several articles online (which is probably what is adding to my confusion).

The manual and the master cylinder cap both say to use DOT 3 brake fluid, but I'm wondering if I can move up to DOT 4 for the higher boiling point as a safety margin. I've read that the 2 types should not be mixed except in a situation where the right type is not available. I've also read that it is ok to mix DOT 3 and DOT 4 because they are both glycol based. I've also read that it's ok to replace DOT 3 with DOT 4. Since I'm planning a complete flush and replace, I'm thinking that it will be OK to use DOT 4. As far as I can tell reading specs and wiki and tech articles, there is no component in either that might harm components such as disc pistons and wheel cylinders, but I don't know that for certain. DOT 3 is a little less expensive but DOT 4 has higher dry and wet boiling points.

I'd appreciate advice from knowledgeable people who have done this.

TIA

 

Dot 4 is usable in dot 3 systems, but you cant put dot 3 in a dot 4 system. It really takes a lot for brake fluid to boil, you have to be using the brakes while driving at very high speeds, higher than most of these trucks will go in their entire lifetimes. So it would make more sense to use dot 3, but it wont hurt anything if you would rather use dot 4.

 

DOT4 brake fluid is not "better" than DOT3, in the same way that diesel is not better than gasoline or jet fuel. They're different - they have different applications. All these trucks are designed to use DOT3 - that's what will give the best performance.

 

Consider replacing the 3 rubber brake hoses when your system is apart for maintenance. Use the Dot 3 fluid.

 

I would flush and fill it with DOT 3. If you did hard braking on Pike's Peak, I would go with DOT 4.

 

Most folks are not likely to experience brake fluid boil but I run DOT4 in everything but change fluid every couple of years.

 

I never change original parts unless they're due on the maintenance schedule (and brake hoses aren't) or they fail some published test (including "visual inspection"). I trust 30-year-old OE Ford parts FAR more than new chinese junk. If the hoses have only ever carried DOT3, they should never age. None of mine have, but I still collect spares in the JYs:

(phone app link)


I change some of the fluid every time I do brake work, simply by removing most of the fluid from the reservoir, and refilling with new fluid. That way, the fluid gets changed progressively, with no chance of introducing air into the working parts.

 

I normally wouldn't even bring this up, but you seem like a smart guy with a lot of information behind you.

When it comes to brake hoses on these trucks, they don't have a maintenance interval besides "replace when they start collapsing internally and causing issues." But on my sport bikes, the maintenance schedule says to flush the fluid yearly (which I do, and I can feel the difference each time) and beyond that, to replace the rubber hoses every couple years, regardless of light/normal/severe use. Do you have any idea why the interval might be so different? In my mind, a rubber brake hose is a rubber brake hose, but the manual is very clear with this, and has been over the course of my 7 bikes.

 

Agreed. My truck was purchased from an older gentleman who inherited it from his father, who bought it new. It definitely had some deferred maintenance in all of its systems. The brakes worked but were lackluster at best, no fun to drive in everyday rush hour traffic. The rear ABS light was on sporadically. The brake fluid was dark, obviously not replaced in quite some time. The rear hose was original and looked it. The shoes, however, were new and the drums looked to be freshly turned. After replacing the rear hose, and then the rear wheel cylinders due to one of the bleeder screws breaking off, the truck stops like a completely different truck. The pedal is firm and responsive. The ABS light hasn't even blinked on in months. Even if there is not a service interval for brake fluid and hoses there is still a noticeable improvement after such service. With the originals being 29 years old replacing them gave me peace of mind, and much better stopping power. I prefer OEM parts and American made parts if there is a choice, but old brake hoses are not what I want to depend upon everyday. I've owned a car with a collapsed brake hose and it put me into a scary situation. I'd prefer not to repeat that scenario. Stay safe!

 

Not exactly, and a motorcycle is not a pickup truck. Ford designs its parts, and writes specifications for them; then it finds manufacturers who will produce them and supply them to the Ford assembly line. Your bike's parts are not likely made by the same manufacturer or to the same specs as your truck's, so naturally, its parts have different maintenance requirements. And that doesn't even get into the different application... The maintenance & intervals on the body of an airplane are not the same as those on the body of a pickup, so apply that logic to your motorcycle brakes.There certainly is.The originals were probably made in USA, and regardless how old they are, they're probably higher-quality (even at this age) than any new hoses, including Ford/MC. Until I have a specific reason to suspect there's a problem with a non-maintenance part, I keep using it. I trust that Ford knew what parts would need to be replaced preventatively, and listed them on the schedule.I've owned a car with a new brake hose that failed and it put me into a scary situation. I'd prefer not to repeat that scenario.