930 41k Wheel loader Brake cylinder leaking.

[MickWalla]

Im hoping I can give enough information for help. My father in law has a 930 loader 41K2997. He's just put new brake master cylinders on, but both seem to be leaking all the fluid from the back. Any help would be appreciated.

 

[Nige]

He's just put new brake master cylinders on

What problem was he trying to address by replacing the master cylinders.?

See attached. System Operation & Test&Adjust for the brake system. Be careful with the SysOp, there are three possibilities depending on Serial Number and you need to make sure you're looking at the right one.

 

[MickWalla]

Thank you. When he was doing maintenance he noticed the valves were broken and seals were no good on the older ones.

 

[kshansen]

I personally never worked on a 930 smallest Cat loader was probably a 966 of some vintage. One thing I noticed in the SysOp.pdf is depending on what page you are reading they refer one time to "brake oil" and another time "brake fluid". Been many years and not had first morning coffee but seem to recall some of the machines I worked on used brake fluid, like DOT3 while others used I seem to recall SAE 10 hydraulic fluid.

I would be double checking a maintenance manual very close for this machines S/N to be sure the correct fluid/oil was being used!

 

[MickWalla]

I personally never worked on a 930 smallest Cat loader was probably a 966 of some vintage. One thing I noticed in the SysOp.pdf is depending on what page you are reading they refer one time to "brake oil" and another time "brake fluid". Been many years and not had first morning coffee but seem to recall some of the machines I worked on used brake fluid, like DOT3 while others used I seem to recall SAE 10 hydraulic fluid.

I would be double checking a maintenance manual very close for this machines S/N to be sure the correct fluid/oil was being used!

This is exactly what I've been suggesting to him. Cause it would also explain the deterioration of the old ones.

 

[OzDozer]

I don't understand what component is being referred to, when the statement is made, "the valves were broken".

I owned a 930, 41K1726. I did plenty of work on the brakes, because they were constantly leaking brake fluid past the pistons in the wheel cylinders. I initially used regular auto brake fluid (for about 10 years), which fluid was recommended in the book.

However, the seals on the wheel cylinders were a constant pain because they wouldn't seal brake fluid properly.

Part of the problem seemed to be the wheel cylinders would let moisture into the system, and this degraded the brake fluid and caused corrosion, which worsened the leaking problems.

I STR all of the hydraulic components of the system were all standard Wagner brake components - master cylinders and wheel cylinders.
I bought standard Wagner replacement parts from a brake and clutch supplier anytime I did repair work on it.

I ended up overhauling the entire hydraulics of the braking system and replacing all the seals - then I changed the braking system fluid to silicone brake fluid.
The silicone brake fluid was more difficult to source, and more expensive (this was mid-1980's) - but changing over to silicone brake fluid cured all my leaking brake problems.

There were two advantages to the silicone fluid - it was a heavier viscosity, so less prone to find its way through small gaps - and it's non-hygroscopic, meaning it doesn't absorb moisture, so it doesn't create corrosion problems.

The major thing I had to do, when others worked on or maintained the 930, was to ensure that the braking system was labelled "silicone brake fluid only", so that there were no problems with contamination with regular brake fluid.

 

[Nige]

Thank you. When he was doing maintenance he noticed the valves were broken and seals were no good on the older ones.

Sorry, doesn't make sense to me either.

Do you know what type of fluid he is using in the brake system.?
Any idea what was the source (and make) of the replacement brake cylinders.?

How soon after installation did the replacement master cylinders start leaking and where exactly are they leaking from.? "The back" as per your OP doesn't exactly give much of a clue. Try posting a photo or two might help.

 

[MickWalla]

Sorry I'm not very helpful. All this might as well be another language to me, and the machine is 4 hours away while I'm trying to get information from my 82 year old father in law.
He's told me he's using dot 3 brake fluid, the master cylinders are brand new replacement for wagner lockheed fd2704. The new ones have been leaking since installation.
Could it just be a missing o ring from between the master cylinder and air over hydraulic?
This is the only photo I have at the moment but I'm not sure how helpful it will be.

 

[Nige]

He's told me he's using dot 3 brake fluid,

That is correct for that machine Serial Number provided that (AFAIK) the replacement master cylinders he bought are of the appropriate type for Dot 3 brake fluid.

Is that photo you posted of the old master cylinders or the replacements.? The two in the photo don't look very new to me.

 

[MickWalla]

No they're the new ones, for some reason he painted them, so will also make it difficult getting exchanged if they're found to be faulty. I've asked him to try and send me a video of it leaking so I can be more helpful in my description.

 

[Nige]

An arrow on the photo pointing to where they are leaking would work. You can’t post videos direct to this forum, first you have to upload them to YouTube then link them.

 

[kshansen]

Just a question or two, where did you source those master cylinders? Was it some place that deals in these kind of things a lot? Just wondering if these have been sitting on a shelf for years and the seals dried out or the bores got rusty.

 

[Rusted]

Remember having what sounds like the same problem on a 920 (same system), where excess piston travel allowed fluid to leak via the drain hole in the booster.