Komatsu D21A-6 - Hydraulic Control Valve Flare Nut - Removal

GBT70

New User
Need advice on breaking the nut on a hydraulic line running into the hydraulic control valve on a Komatsu D21A-6 dozer.

I don't know the maintenance history of the dozer. but, i am in the process of servicing the dozer for the following.

1. Removing to service the Hydraulic Control Valve
2. Removing and Replacing the engine Fan blade
3. Replacement of the steering clutches

I have been unable to remove the hydraulic control valve do to the lines connected to it. The Nut and Back Nut are just nut breaking free of one another.

1. Line Nut 30mm
2. Back Nut 26mm

I need specific advice on what steps are best used to break free the lines identified in the photos. As in, specific tool types. Penetrating Oils, Heat and or any other options that are commonly used with heavy equipment.

I have used PB Blaster and my favorite penetrating oil "KROIL" But So far nothing seems to work. I feel like i need specific tools for breaking the nut. (Pictures and Links Requested)

See pictures below.
 
(quoted from post at 11:03:45 04/17/16) Need advice on breaking the nut on a hydraulic line running into the hydraulic control valve on a Komatsu D21A-6 dozer.

I don't know the maintenance history of the dozer. but, i am in the process of servicing the dozer for the following.

1. Removing to service the Hydraulic Control Valve
2. Removing and Replacing the engine Fan blade
3. Replacement of the steering clutches

I have been unable to remove the hydraulic control valve do to the lines connected to it. The Nut and Back Nut are just nut breaking free of one another.

1. Line Nut 30mm
2. Back Nut 26mm

I need specific advice on what steps are best used to break free the lines identified in the photos. As in, specific tool types. Penetrating Oils, Heat and or any other options that are commonly used with heavy equipment.

I have used PB Blaster and my favorite penetrating oil "KROIL" But So far nothing seems to work. I feel like i need specific tools for breaking the nut. (Pictures and Links Requested)

See pictures below.
 
Not sure about the issue regarding breaking the nut loose...I think you mean it"s too close to an adjacent one to get room to wrench on it? If the other one cannot be removed first, giving you access...look for a "butterfly socket"...it"s a 2-piece hex hinged "socket" that can wrap around, and lock, onto the nut. Uses a half inch or 3/8 drive handle. google it for pix of the wrench. They are difficult to find at auto parts stores.
 

Placing a wrench on the Nut and Back nut is not an issue.

I simply cannot put enough force on the nut to break it.
I need solutions as to how to Heat the nut. For how long. or, specific tools used by individuals that run into this issue.

I have not been able to locate anything on the subject on You Tube or Google.

its almost like the Nuts are welded together. Now I don't believe that is the case. but that doesn't mean someone used JB weld years ago on the threads.

most likely case is that the line has never been taken off and the factory thread lock and perhaps rust are the main issue.

ill see if I can get the picture to post.

thanks for the reply. I will look up the butterfly socket.
35199.jpg
 
(quoted from post at 11:03:45 04/17/16) Need advice on breaking the nut on a hydraulic line running into the hydraulic control valve on a Komatsu D21A-6 dozer.

I don't know the maintenance history of the dozer. but, i am in the process of servicing the dozer for the following.

1. Removing to service the Hydraulic Control Valve
2. Removing and Replacing the engine Fan blade
3. Replacement of the steering clutches

I have been unable to remove the hydraulic control valve do to the lines connected to it. The Nut and Back Nut are just nut breaking free of one another.

1. Line Nut 30mm
2. Back Nut 26mm

I need specific advice on what steps are best used to break free the lines identified in the photos. As in, specific tool types. Penetrating Oils, Heat and or any other options that are commonly used with heavy equipment.

I have used PB Blaster and my favorite penetrating oil "KROIL" But So far nothing seems to work. I feel like i need specific tools for breaking the nut. (Pictures and Links Requested)

See pictures below.
35200.jpg
 
Use your air gun with a chisel . Get a little
notch cut in the nut, then re aim the chisel in
the direction to unscrew it . Done it several
times on excavators ....
 
(quoted from post at 14:43:33 04/17/16) How about the old plumber's trick of tapping (Moderate impact) on the sides of the nut for a little while?

I forgot to mention that I have been using a ball peen and hitting the nut in an effort to help the KROIL penetrate.

I Appriciate the reply...
 

Dalex,

Thanks for the reply.

So is this possibly normal when nuts have never been removed?

I don't have an Air Gun. But I will pursue the option.

How much damage does this do to the Nut? Are you able to place a wrench on it afterward to tighten the nut or do you have to grind the nut a little to remove the deformity the nut incurs?
 

I accept all questions as I am the one asking for your support on how to deal with the problem.

One of the first steps in the Shop manual is to ensure the pressure is out of the system. I complied with all the initial steps outlined in the shop manual.

also, I have the opposite end of the Tube broke free.

35208.jpg
 
If you don't have an air hammer, use a tapered punch about 10mm dia. on the end. Work up and down the flat of the line nut. Do more than one flat if possible.
 
That size of fitting should not be that tight or difficult to remove. Do not apply heat if there are adjacent valve bodies unless you plan on rebuilding them. Use a backup wrench, brace it however you have to. blocks etc. put all force on B nut, using a cheater if you have to. The main thing is put all force inline with rotation to remove. extreme cases use a porta power braced against other structure to rotate wrench on nut. I hope this helps.
 
Stacked assy, you will have to remove them in order. It's there, figure out the puzzle. This is encouragement, I have run across similar assy's and I work on Komatsu's for a living. Even if someone used locktight in the past out of desperation you can still break it loose. You may have to modify wrenches, cut tips back to get full engagement in the throat of the wrench. (I almost have a full set now)
 
sounds like someone before you used Loctite 545 hydraulic thread se3alant. may have to heat the nut until you can smell the Loctite burning. let it cool and it should be easy to loosen. good luck
 

I appreciate all the suggestions. Forums are a great tool for reaching out for information.

It's raining here in Oklahoma today so I will have this week to gather my tools and put some of these tips to the test.
I will respond back with the method that works as soon as things dry up.

I will be posting more information on my D21A-6
Progress. More to come!
 
I work on equipment and run into this all the time. The best bet is a hammer and a punch, or an air hammer. In either case, work the hammer around the flat or flats if more than one is easily accessible. Once you get through, you'd me amazed how easily it will break free. Personally I've put a 1 1/2 wrench, with a cheater, on one, and it wouldn't break free. A few 'love taps' with a hammer and I backed it off with my hand.

Beyond that, unless it's had a locking compound put on it, and it needs a bit of heat to free it up, it should come right off, with a hammer and the correct size wrenchs.
 
It appears from the pictures that you have sufficient room to get a half-inch drive "Crowsfoot" wrench on the nut. Use an extension and a
half-inch drive Impact Wrench on the "Crowsfoot", (combination of vibration & torque) .


HTH

Doc
 
That nut was not coming off.
Finally just called in a Dozer service Mechanic
I just don't have the tools in my garage yet to
Work every issue on this Dozer.

But... That being said. The valve assemble is now rebuilt and
reinstalled and working great. No leaks.
 

We'll never know Andy because most folks here refuse to use the modern format of this forum like you and I have to bring this thread back up to the top.

Our posts will never be seen by the majority here who stubbornly cling to an inferior system that never brings comments to the top.

It's as frustrating as hell, I've pretty much given up offering any advice because I don't get on here everyday and when I post no one ever sees it.
 

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