[bob123]

I have looked over the owners manual many times and not once has Jeep recommended flushing the brake fluid.

I have read brake fluid absorbs moisture over time which lowers the boiling point causing the fluid to form into a vapor.

Should we get our brake fluid flushed every three or four years or don't bother with it (according to the manual)?

 

[Mongo]

According to Chrysler Brake Fluid is a lifetime fluid and does NOT need to be changed. They also consider the vehicle life to be 100k miles, and if you want to last longer, I'd consider changing those "lifetime" fluids.

The brake fluid will abosrb moisture right out of the air and suck it through the rubber hoses and seals, this lowers the boiling point of the brake fluid and if you get your brakes hot, it could flash into vapor and reduce the braking force and response on your brakes. NOT likely to happen, but "I" consider it a worthy reason, amoungst others, to flush the brakes myself.

Racing causes brake fluid to boil, the only cases on the street I've heard of boiling brake fluid, has been 10 year old brake fluid in a vehicle that the owner rode the brakes the whole way down a mountain side. So, again, possible, especially if you're stupid, but unlikely. If you tow a heavy load in a hilly area, you may be getting into that sever service that could boil 'wet' brake fluid.

Fresh brake fluid that does NOT have water in it, is far more likely to keep your brake components lasting longer and more trouble free, the hydrualic parts.

Personally, I would flush the brake fluid every 3 or 4 years, actually I do it more often, but I admitt, I'm doing overkill.

If you mess up the brake bleeding bad enough, you could get air in the ABS module, the only way to bleed the ABS module is with a Dealer Scan Tool. I've bled brakes for years on my Chrysler ABS vehicles and never had this happen, but it is a risk. If it happens, its just a quick trip to the dealer, although they'll always charge more than they should for the service.

 

[bob123]

After four or five years brake fluid can only hold so much water, correct? I guess what I am asking: Six year old brake fluid is the same as 10 year old brake fluid chemically, but the difference is how long brake components are in contact with the bad fluid.

 

[robby]

Bob,
To a degree, your operating environment affects this service.
Those of us in high humidity/damp areas of the country probably would do well by changing the fluid every two or three years.....specifically to reduce the potental of corrosion within the system and especially to protect the ABS control unit.
Many small valves within a rather large block of aluminum.

As mentioned earlier, there is a visable warning of contamination....that being the fluid turning dark....ultimatly almost black.
There are litmus strips for testing brake fluid for moisture and there is a battery power tool for the same purpose.
It has two contacts visible and when dipped in the fluid will shoow a resistance value.
Low resistance is high water content, high resistance, the inverse.

Years ago, prior to ABS, master cylinders and calipers/wheel cylinders were made of cast iron.
Those cars were often junked with the original brake fluid still on board.
Two things allowed us to get away with it....1. the cast iron parts tolerated that evil old fluid fairly well and 2. the large brakes used then, along with asbestos pads and shoes, did not carry much heat into the hydraulic components.
Now, in addition to aluminum components, we have metallic friction compounds and they carry the heat right into the calipers......and the potental of boiling brake fluid presents itself.
Kind of dire sounding, especially since we likely would never get the system that hot anyways, as Mongo noted.

I like looking at clear fluid, knowing I have done all I can to prevent a hydraulic failure due to moisture.....for me, in Northern Illinois, that means a fluid change every three years.

To the gang down in the desert Southwest.....you likely can leave the fluid alone for the life of the vehicle if it isn't changing color.

Rob

 

[bob123]

Instead of flushing the brake lines, can I just replace the brake fluid in the reservoir? Is this sufficient enough?

 

[Mongo]

Instead of flushing the brake lines, can I just replace the brake fluid in the reservoir? Is this sufficient enough?

NOT really, the brake fluid doesn't circulate, most of the fluid in the reservoir goes unused, unless you have a leak in the brake system.

It will work its way into the lines slowly and circulate some. But for the most part, the old fluid with water in it is sitting in the lower parts of the brakes.

Its pretty easy to bleed brakes, although you need a helper. Google it and you can find the principles and procedures.

Personally, I use speed bleeders, they are brake bleeder screws with a one-way check valve in them. All you have to do is loosen the bleeder screw and pump the pedal, then tighten it again.

I've posted the info for the speed bleeders, its like $20-$40 for a whole set to outfit the vehicle. Do a search for the thread.

[EDIT]
Link to the thread:
http://www.jeepcommander.com/forums/showthread.php?t=14372&highlight=bleeders

I was able to find a reference on a Speed Bleeder Website, they list a

M10-1.0 31.35mm length

Bleeder Screw Front and Rear on the Commander.

Speed Bleeder part num SB1010S
Russell part num RUS-639630

I ordered a set from Summit

 

[tempestv8]

Just bled the brakes on my brother-in-law's 2006 Commander CRD.

The genuine Mopar bottle sold by the dealer is such a small bottle. Best to buy TWO of these bottles to get the job done satisfactorily. Cost was AUD$15 per bottle, which has 355 ml of fluid.

The first thing that I did was to extract the existing old fluid from the reservoir in the engine bay. I figure, no point pushing that old fluid in the reservoir down the lines. I didn't want to go too low, so I took out fluid using a big plastic syringe until the the fluid was down to the "low" marker.

From here, one whole bottle of fresh fluid was poured into the reservoir.

I note that the fresh fluid was clear, but what was in the reservoir looked reddish black. Not sure if that's what happens to the original fluid due to age, or if the previous owner used a different fluid which had a red dye in it. Regardless of whether Chrysler say that the fluid is "lifetime fluid", the colour of the fluid (nearly black) didn't look very good at all.

I used the traditional two man method of bleeding the brakes. One person (brother-in-law) on the brake and myself underneath with a 10 mm ring spanner to undo and tighten the bleed valves. I only allowed enough fluid to come out such that the brake pedal only get to the half way point. I am not a fan of allowing the brake pedal go nearly all the way to the floor, as the seals in the master brake cylinder would not have travelled that far into the cylinder, and may get damaged.

Fairly easy job, and managed to go through nearly all of the 2nd bottle. It's possible to do the job without removing the wheels, and a plastic hose and bottle to catch the old fluid helps keep the mess to a minimum. Now I have to dispose of the old fluid properly by going to the council's waste transfer station.