2004 w22 Filling Brake Fluid Reservoir

[prsmith]

Good morning,
I feel pretty stupid about these questions

I assume that the Brake fluid reservoir has two compartments that are connected - is this so? 1e, the fluid level will equalizer itself between the two compartments

Written on my plastic tank (which I cannot see through), are teh words "fill to bottom of rings" - what rings? The only ring I see from the exterior is the seam bewtween the top and bottom pieces of the tank. Am I missing something obvious?

Elsewhere it says that we fill to within 1/4" (+- 1/8") of the lowest part of tank top - this pretty much negates the seam as the ring in question.

Inquiring minds need to know more about the fill level

I bought my used rig in June - it is exactly 5 years old with about 21k miles on it

On my repeated asking the dealer told me that the previous owner said that the brake and tranny fluid, and coolant had never been drained. So I am starting the process

I drained the brake fluid and it is black, black, black. I will replace it with Dot 3 Ford fluid

I assume that since the brake problem is supposedly caused by the phenolic pistons absorbing water, the use of new fluid might just suck some of the moisture out of the pistons - does this make sense? If so I should probably change the fluid again in 4 or 5 thousand miles

Thanks,

Preston

[DriVer]

Quote:

Originally Posted by prsmith Good morning, I feel pretty stupid about these questions

prsmith, No such thing .. ask away.

Quote:

I assume that the Brake fluid reservoir has two compartments that are connected - is this so? ie, the fluid level will equalizer itself between the two compartments

The Bosch Hydro-Max has 2 separate compartments that are independent. If you recall filling a battery cell, just fill the master cylinder in the same manner bringing the fluid up to about 1/2" lower than the top of the opening on the master cylinder. This should give you a level within the specs you're quoting. Make sure that the caps and top of the tank are free from soil, grease or debris before removing them.

Quote:

I bought my used rig in June - it is exactly 5 years old with about 21k miles on it. On my repeated asking the dealer told me that the previous owner said that the brake and tranny fluid, and coolant had never been drained. So I am starting the process.

I would replace all the fluids and don't forget to check the differential fluid. Replace it if its discolored at all. This vehicle might be equipped with Transynd and you can tell by the VIN#.

Quote:

I drained the brake fluid and it is black, black, black. I will replace it with Dot 3 Ford fluid

I would save the money and simply buy Prestone DOT3 at WalMart and change the fluid every 24 months.

Quote:

I assume that since the brake problem is supposedly caused by the phenolic pistons absorbing water, the use of new fluid might just suck some of the moisture out of the pistons - does this make sense? If so I should probably change the fluid again in 4 or 5 thousand miles.

Do not assume this. No amount of brake fluid changes are going to absorb the water in the pistons. You are going to be included in the recall so I would try to hold out until the campaign can be applied to your vehicle. Make sure that you are listed as the owner of record. Going forward the new pistons are impermeable.

[prsmith]

Quote:

Originally Posted by DriVer The Bosch Hydro-Max has 2 separate compartments that are independent. If you recall filling a battery cell, just fill the master cylinder in the same manner bringing the fluid up to about 1/2" lower than the top of the opening on the master cylinder. This should give you a level within the specs you're quoting. Make sure that the caps and top of the tank are free from soil, grease or debris before removing them. I would replace all the fluids and don't forget to check the differential fluid. Replace it if its discolored at all. This vehicle might be equipped with Transynd and you can tell by the VIN#. I would save the money and simply buy Prestone DOT3 at WalMart and change the fluid every 24 months. Do not assume this. No amount of brake fluid changes are going to absorb the water in the pistons. You are going to be included in the recall so I would try to hold out until the campaign can be applied to your vehicle. Make sure that you are listed as the owner of record. Going forward the new pistons are impermeable.

DriVer thanks for your input and I apologize for my late reply

My Bosch master cylinder has two compartments that are in fact connected. It took me forever to suck the old fluid out of one compartment and when I got a dry sucking sound on the second compartment I was pretty sure they were connnected. While filling one compartment the second one 's level rose at the same time

I will use the local Allison shop to service the tranny - I will watch what they do and do it myself next time. It will cost less than an hour's labour to 'learn' from them. I will also found someone to flush and replace the Dexcool - they can have the disposal problem

You mention checking the diff fluid for discolouring - what will I be looking for (in addition to the level)?

I had used the Wal-mart Prestone Ford spec brake fluid - next time I will use the regular Prestone fluid.

The Workhorse page shows me as the owner of record even though they say in a note at the bottom of page that they will action the requested page in due course.

Can I send you my VIN number to confirm that WH has the correct info? Or can I trust what is on the page.

I live in Nova Scotia Canada and the nearest WH service is in Bangor Maine. I asked in another area of this forum if the shop has a good reputation (no response as yet). My plan is to have the recall done as I head to Texas in late November - an alternative location to get it done is in Reading PA where I understand there is a good service center. In any case I have to make an appointment ASAP to get it done while in transit. Alternatively I can wait until I arrive in Mission TX and have it done there although I hate to push my luck

Thanks for your knowledgeable input - it is very very much appreciated

Preston

[JCM]

I had my front shocks replaced and the rotors turned at that dealership in 2005. Good service but they said that it would take a week to get in the replacement Munroe Magnums (I had made an appointment 2 weeks earlier). I said that I was going to leave and all of a sudden they found 2 in their parts supply. In all I would recommend them but..

[DriVer]

Quote:

Originally Posted by prsmith My Bosch master cylinder has two compartments that are in fact connected. It took me forever to suck the old fluid out of one compartment and when I got a dry sucking sound on the second compartment I was pretty sure they were connected. While filling one compartment the second one 's level rose at the same time.

I can't explain why your fluids went up and down via one fill hole but the entire idea of having 2 separate and distinct fluid compartments is a engineering standard that can not be compromised. If you loose all the fluid in the steer axle you will still have a viable rear circuit to apply the rear brakes.

Bosch Hydraulic Training Display (PDF)

Take a look at this testing device. If you look at Page 7 in the Failure Modes, you will see

9. Steer axle hydraulic failure

10. Drive axle hydraulic failure
To isolate the failure modes it would be impossible to achieve if the fluids commuted in between the reservoirs.

Now here's the Bosch Hydro-Max Hydraulic Booster and Master Cylinder (PDF)

If you review the blue prints you will clearly see a vertical wall in between the 2 chambers in the Master Cylinder reservoir.

There are indeed two separate chambers and each require filling and observation to determine that they are both filled.

Quote:

You mention checking the diff fluid for discoloring - what will I be looking for (in addition to the level)?

Open the differential fill plug and observe that the fluid is completely black and absent any appearance of being "milky" or having any traces of while fluid. If the rig is completely level (make sure) the fluid may flow out of the differential and allow it to do so. If there is no flow fill the differential until the fluid is level with the bottom of the fill hole.

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I had used the Wal-mart Prestone Ford spec brake fluid - next time I will use the regular Prestone fluid.

Save a few bucks right there I expect plus you want to meet or exceed GM 12377967 which is not just a number they pulled out of their hat. It's quite a robust fluid that you can investigate further if you need to.

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Can I send you my VIN number to confirm that WH has the correct info? Or can I trust what is on the page.

Send me the last 8 digits of the VIN# in PM please.

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My plan is to have the recall done as I head to Texas in late November - an alternative location to get it done is in Reading PA where I understand there is a good service center.

I would say call now and make an appointment for November. They should be able to fit you in if they can book an appointment for that time.

[prsmith]

Quote:

Originally Posted by DriVer I can't explain why your fluids went up and down via one fill hole but the entire idea of having 2 separate and distinct fluid compartments is a engineering standard that can not be compromised. If you loose all the fluid in the steer axle you will still have a viable rear circuit to apply the rear brakes. Bosch Hydraulic Training Display (PDF) Take a look at this testing device. If you look at Page 7 in the Failure Modes, you will see 9. Steer axle hydraulic failure 10. Drive axle hydraulic failure To isolate the failure modes it would be impossible to achieve if the fluids commuted in between the reservoirs. Now here's the Bosch Hydro-Max Hydraulic Booster and Master Cylinder (PDF) If you review the blue prints you will clearly see a vertical wall in between the 2 chambers in the Master Cylinder reservoir. There are indeed two separate chambers and each require filling and observation to determine that they are both filled. Open the differential fill plug and observe that the fluid is completely black and absent any appearance of being "milky" or having any traces of while fluid. If the rig is completely level (make sure) the fluid may flow out of the differential and allow it to do so. If there is no flow fill the differential until the fluid is level with the bottom of the fill hole. Save a few bucks right there I expect plus you want to meet or exceed GM 12377967 which is not just a number they pulled out of their hat. It's quite a robust fluid that you can investigate further if you need to. Send me the last 8 digits of the VIN# in PM please. I would say call now and make an appointment for November. They should be able to fit you in if they can book an appointment for that time.

Hi DriVer,

Thanks again for your help and effort on my behalf.

Not to argue with you (because I may be way off base), if you look at page 5 of the Bosch Manual, 4th para says "When the load on the primary piston is removed, etrc.etc Each actuator opens its respective compensating valve , reopening the passage between the individual reservoir sections and its associated pressure chamber." Also there is only a single low fluid level warning sensor implying that the reservoirs are connected. Not really clear though - what you say makes sense but this para and the single sensor implies otherwise. In any case, I removed all of the fluid via a single reservoir and on checking the other one it was bone dry. I refilled via a single reservoir and they both came up to the correct level

With regards to the differential, I assume the white fluid or milky appearance is caused by water contamination. I will have a close look at mine

In looking at GM P/N 12377967 (Canadian P/N 992667), I get the impression that these products are DOT 3 - most references to the GM numbers say "or equiv DOT 3") - I was not able to find any reference to the GM Number/spec on the Prestone site. But I feel quite comfortable with the Prestone product

Agree wrt getting an appointment - I will do that ASAP so that I am not left high and dry

My VIN will follow via a separate PM.

Thanks again for your help - you sure have a great memory bank full of info

Preston

[prsmith]

Quote:

Originally Posted by JCM I had my front shocks replaced and the rotors turned at that dealership in 2005. Good service but they said that it would take a week to get in the replacement Munroe Magnums (I had made an appointment 2 weeks earlier). I said that I was going to leave and all of a sudden they found 2 in their parts supply. In all I would recommend them but..

JCM,

Thanks for your note

Are you referring to the service centre in Bangor ME or the one in Reading PA?

Thanks

Preston

[bsinmich]

On my 2003 chassis the divider in the master cylinder goes up about half way to the top of the reservoir and from there up it is one big tank. When I filled I only had to do from one of the openings because they were both full. That would fulfill the requirement of 2 independent reservoirs.

[JCM]

The one in Bangor Main. It was the closest to the border as we went south. The work was excellent but I questioned their attitude. It was when the first Monroe shocks were deamed to be a poor design and my wife got tired of us bouncing all over the roads in Newfoundland - we got Monroe Magnums. 2 years ago I switched to Koni shocks - sometimes a better ride than my present air bag coach.

[DriVer]

Quote:

Originally Posted by prsmith ... if you look at page 5 of the Bosch Manual, 4th para says "When the load on the primary piston is removed, etc.etc Each actuator opens its respective compensating valve , reopening the passage between the individual reservoir sections and its associated pressure chamber."

Preston, Learning something new everyday is what we should all strive to do. In my thought process I was too wrapped up with what happens after you step on the brake pedal.

When I drained my tank for bleeding I was alternating tanks and could not directly observe the level in both going down simultaneously.

Thank you for your research on this issue. I can clearly see where your method would indeed work as you described it.

√ to bsinmich too!

[Joe Gilbert]

bsimnich is correct. My 2005 is just like his 2003. The top of the master cylinder tanks are common. I too have a problem seeing the level of nice clear, new, DOT 3 (we are suppose to keep clean fluid in these aren't we?). I simply wipe my finger clean and use it for a dip-stick to get the level correct.

Now! having said that if your draining the tanks you must do both sides to get all of the fluid out. I syphon out the old DOT 3 with a clean hose, refill with new DOT 3, than start bleading the brakes. An easy job if you install speed bleaders.

JoeG

[oemtech]

I use my portable air compressor and a vacuum bleeder to empty the Master Cylinder.



To refill the Master Cylinder I used my modified garden sprayer to add the brake fluid.



Note - I normally use Wal Mart's best Dot 3 fluid. But, the Dot 4 in the photo was on sale for the price of Dot 3.