Brake fluid

kb0jyl · Unread post by **kb0jyl** » January 26th, 2008, 1:19 pm

Have to redo my brakes on my 65 M151A1, and need to know if you can use any brake fluid or if you have to use the silicone brake fluid. I reallydon't want to have to do brakes again real soon, so just as soon get it right the first time.

Thanks
Steve

Spike · Unread post by **Spike** » January 26th, 2008, 5:45 pm

If the system is currently DOT 5 (silicone) don't change to another fluid type (DOT 3/4) and vice versa. They are totally incompatible and you will end up with a congealed mess. Some people have flushed their system with mineral spirits thinking they abated all the brake fluid only to find out they left a few droplets which caused them a partial failure later. I think it took two pints to bleed and refill my system the last time I changed fluid. TM 218-34-1 page 12-2 says fluid capacity is 8.00 ounces.

DOT 3 and 4 are hydroscopic, they absorb moisture. DOT 5 does not (5.1 does) If it's older and the color of Pepsi it's DOT 3/4. Just to make sure, mix some of your brake fluid from the master cylinder with water, if it blends with the water it's DOT3/4 if it doesn't it's DOT5.

I use a turkey baster or something like it to evacuate the fluid from the master cylinder, I refill, cap and start bleeding, the bleeding sequence is: 1st) passenger rear, 2nd) driver rear, 3rd) passenger front, 4th) driver front. Check/refill the master cylinder as you're bleeding.

My guess is you have DOT3 now. Look for a yellow sticker or the remnants of one just above the master cylinder filler. If it has that sticker it was changed to DOT5 at some point.

k8icu · Unread post by **k8icu** » January 27th, 2008, 12:52 am

There has been alot about this on other boards and some wright ups in things like MV mag. The conclusion and consensus seems to be that Dot 3/4 and Dot 5 don't mix or play well with each other, but that you wont get a jelly mess.

When the Army changed all vehicles from Dot 3 to Dot 5 the MWO was to drain the systems dry and then refill with the new fluid. I had a motorpool sgt tell me that they flushed the system with rubbing alcohol and then refill and I've done that myself with successfull ressults.

moose53 · Unread post by **moose53** » January 27th, 2008, 1:01 am

I prefer the DOT5 silicone for the same reason as the military did...our jeeps sit in their garages more than anything and the dot-5 doesn't absorb water. therefore it deteriorates less from lack of use.

Jim

SV2IPW · Unread post by **SV2IPW** » January 27th, 2008, 3:08 pm

Personaly,i use Bell Ray DOT-5 Brake fluid for motorcycles, with exellent results.