No more D.O.T 5 brake fluid for me

[Fordestes]

I have Dot 5 brake fluid in my truck, I want to go back to Dot 3 or 4 ,
this fluid is being pulled into my intake from the brake booster line and gumming up the plugs, this is the second master cylinder and booster in a short time that started leaking , what do I need to flush out the brake system with to get rid of the dot 5 fluid without rebuilding the whole system again.
all the wheel cyliders are nearly brand new and this master cyl. isn' t very old, I dont drive the old girl much and was thinking of the moisture build up from brake fluid, from now on I will have to make sure the brakes are flushed on a regular basis.someone said alcohol, but what kind of alcohol or is this a no no too surely there is something that can be used to flush this garbage out of my hydraulic system.
Fordestes,

[34PKUP]

If you think that by changing the type of brake fluid that's in the system is going to fix an obvious mechanical problem, think again.

[Kube]

Originally Posted by Fordestes

I have Dot 5 brake fluid in my truck, I want to go back to Dot 3 or 4 ,
this fluid is being pulled into my intake from the brake booster line and gumming up the plugs, this is the second master cylinder and booster in a short time that started leaking , what do I need to flush out the brake system with to get rid of the dot 5 fluid without rebuilding the whole system again.
all the wheel cyliders are nearly brand new and this master cyl. isn' t very old, I dont drive the old girl much and was thinking of the moisture build up from brake fluid, from now on I will have to make sure the brakes are flushed on a regular basis.someone said alcohol, but what kind of alcohol or is this a no no too surely there is something that can be used to flush this garbage out of my hydraulic system.
Fordestes,

If you are pulling brake fluid in to the power booster and / or manifold there is an issue other then fluid type.
How is the check valve at the booster? If that's defective, it is possible to pull fluid in to the manifold.
If fluid is getting in to the booster, you have a defective booster and / or check valve.
Me? I'd be getting my next booster and master cylinder from a different source. It is NOT the fluid type causing these parts to become defective.

Flushing fluid requires denatured alcohol.

[Fordors]

I wonder if you have an issue with the brake booster push rod seal, more so than DOT 5 fluid. The seal has to be good to prevent the situation you are experiencing and I would think any fluid would be sucked into the intake, not just DOT 5. Is the booster an "off shore" item you added to the truck? Please post the outcome so we all can learn from this. Regarding flushing I think you will be OK just purging all the DOT 5 from the system by bleeding and filling with DOT 4, but as you said yourself you don't drive this vehicle that often and the DOT 5 would be beneficial to keep.

[51 MERC-CT]

Originally Posted by Fordors

I wonder if you have an issue with the brake booster push rod seal, more so than DOT 5 fluid. The seal has to be good to prevent the situation you are experiencing and I would think any fluid would be sucked into the intake, not just DOT 5.

Even if the booster seal were bad there would not be any fluid to be sucked by the booster unless the master was defective (two defective components)
I have been running DOT5 in my master/booster for over 15 years without an issue.

[Firepower flyer]

Sponsored Links (Register now to hide all advertisements)

I have it in multiple older vehicles with no issues,I agree something else going on.

[Kube]

Originally Posted by Fordors

I wonder if you have an issue with the brake booster push rod seal, more so than DOT 5 fluid. The seal has to be good to prevent the situation you are experiencing and I would think any fluid would be sucked into the intake, not just DOT 5. Is the booster an "off shore" item you added to the truck? Please post the outcome so we all can learn from this. Regarding flushing I think you will be OK just purging all the DOT 5 from the system by bleeding and filling with DOT 4, but as you said yourself you don't drive this vehicle that often and the DOT 5 would be beneficial to keep.

Changing fluids (properly) requires a complete flushing with denatured alcohol.

[mrtexas]

Is your master cylinder OK for silicone fluid? I've seen some that are labeled do not use it.

[tamnalan]

I have a 30-year history with Dot 5 in several vehicles. It's good stuff... kind to paint and helps the corrosion problem.

My only beef with it is that it doesn't surrender trapped air very easily. The best way I've found to bleed a Dot 5 system? In the parking lot on a random Colorado mountain top above 14,000'. Pike's Peak summit, in my case.

[RalphG]

Got to be a problem with the check valve if it is letting brake fluid into the intake manifold. If you don't use the truck much and don't haul heavy loads I would just by-pass the booster and go with manual brakes. Should be plenty adequate for an empty truck and less hassle to deal with.

[paul2748]

I've also used dot 5 in a power brake system (booster)with no problems for about 25 years in the same car.

[expavr]

"Is your master cylinder OK for silicone fluid? I've seen some that are labeled do not use it."

I just had the a 100K mile service on my 2005 Suburban and asked to have the brake fluid changed from DOT 3 to 5 and was told that both the MC and the booster weren't designed to be used with DOT 5. I checked the owner's manual and sure enough it specs DOT 3. There is also a thread on the GMC truck site about booster failure associated with DOT 5. This could be the reason for the problems your having.

[uncle buck]

The only fluid a vacuum brake booster is going have in it is fluid that has leaked from the bore of a bad master cylinder.

[Cecil/WV]

I was using Dot 5 in my '52 F-7 and was warned by Chuck at Chuck's trucks in Ct, when ordering some parts, that if Dot 5 gets in an engine through a booster, the silicone turns back to grit and will destroy the engine. I have used Dot 5 for years in several cars without an issue, but I did remove it from my truck with the vacuum booster and won't use it in my '60 T Bird.

[Fordestes]

AsI stated before I replaced the booster and the master cyl. all new and apparently the fluid isn't compatable with the master cyl. rubber nor the booster seals, they both were short lived,I attribute these frequent failures to the fluid, as the fluid is the only thing I done different, as for the check valve the valve is working correctly ,the vacuume path is going one way to the manifold and checks any pressures as from a backfire or to keep fuel vapors from accumulating in the booster etc. the check valve doesn't know air from liquid. the separation area between the master cyl and the booster is open as the fluid from the master drains out but some of it gets on the booster seal and apparentl cause the booster seal to fail .
I will try the Denatured alcohol to flush out the system and start over with another booster and master cyl. ,that is what I wanted to know ,I couldn't justify completely
rebuilding the brakes when it isn't necessary, and yes! a standard non power brake was the norm for me many many years, but due th physical concerns the power is a necessity for me at this time in my life.
Thanks for the input,Denatured alcohol it is, do I leave the alcohol in for a specific time or just pressure flush it through the system?
Thanks,
Fordestes,

[TomO]

The alcohol will clean the lines and the wheel cylinders of the dot 5 fluid, but I would take the time to rebuild all of the cylinders. If any trace of DOT 5 mixes with DOT 3 or 4, it will coagulate into a sand like material and keep the cylinder from working properly.

[Lanny]

http://forums.mtbr.com/brake-time/si...th-832808.html










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[V12Bill]

A friend of mine had a shop that rebuilt older Ford products. He had a customer that complained of brakes locking up. On examination, he found that the rubber cups in the wheel cylinders swelled up when in contack with DOT 5. He experimented and found that rubber parts that were marked "ADM" were compatible with DOT 5 and others were not. Check the rubber parts in your master cylinder and booster and see it the rubber parts have swollen up.

[trulyvintage]

Originally Posted by expavr

"Is your master cylinder OK for silicone fluid? I've seen some that are labeled do not use it."

I just had the a 100K mile service on my 2005 Suburban and asked to have the brake fluid changed from DOT 3 to 5 and was told that both the MC and the booster weren't designed to be used with DOT 5. I checked the owner's manual and sure enough it specs DOT 3. There is also a thread on the GMC truck site about booster failure associated with DOT 5. This could be the reason for the problems your having.

B-I-N-G-O ....


Same thing happened to me on an older Ford truck ...



Jim

[Fordestes]

no , all the new parts i installed had no mention of specific type of fluid to use , I bought a gallon of silicone fluid and was expecting longevity of the system ,but all I did was to create more problems, some times we cant believe all we read in advertisiments.
Fordestes,