I’ve got a weird issue going on with my d31-16. Haven’t owned machine maybe 7 months, sat for around 10 years before I got it. Engine was bad, rebuilt and reinstalled everything running great. The issue at hand now is that the 6 way blade will tilt way to the left and barely past level to the right. What is odd is that it was doing it the opposite direction. All the way right and barely past level to the left. It changed when I was pushing a fence row and went through a low spot and had blade tilted following the terrain. The rod that connects the tilt cylinder to the blade was bent. I cut out that piece and replaced it with new material that was prior to this new issue. I did lengthen it some because it wouldn’t tilt level. Measured cylinder stroke and lengthen accordingly. I’ve repacked tilt cylinder thinking it was bypassing inside. No difference. Not sure what else to do next. Any info helps! Sorry for the long post!
At the back of the blade down the bottom there is a ball mount for the blade to swivel on . On the inside against the back of the blade there is a clamp , they come lose . Check that . I damaged one and needed to heat it to bend it back to fit properly . This is probably not the issue but needs to be checked first .
I checked it this morning it still looks good.
If there is no worn out mounts for the tilt ram and the main swivel mount for the blade , no cracks to welds to the mount that stands up on the c-frame that the rod connects to the back of the blade check to see if the ram is extending fully and staying fully extended and when its contracted to .If the ram won't hold could be an o-ring in the hydraulic control valve . It would be better for the rod you extended to be factory length . What are the main C-frame mounts like where it mounts to the track frames . Can you post some pictures , I'd like to know if the blade is the same as the one I've used
Sure I can post pictures this evening. I would like to know what the length of the rod is supposed to be from factory. As far as I can tell the cylinder rod is moving full stroke and not bleeding off. You can pickup front of dozer with the blade tilted and it doesn’t push the cylinder back in.
There is so little to go wrong with it unless something has been modified , there are two rams listed , neither show their length difference . It could be an incorrect ram used to replace the original . Rod length not mentioned either , thats a pretty heavy bit of kit to bend if its the rod I've seen .
It’s a piece of 2” steel. I was surprised the old one was bent. I’m beginning to think it’s the problem. But what I don’t understand is what changed like you flipped a switch ?
Extending the rod would put more tilt down on the left and reduce the right which you have . I would sort the length of that , little bit of extra length would make a big difference at the tip of the blade , all the pins look good so theres no loss of function with them . Has the pitch of the blade changed ? The force to compression bend a bit short 2 " steel must have been great . There may be damage to track frames or their mounts maybe a twisted C-frame .
You’re right about the extending of it, when I did extend it the blade would not level out. It was twisted to the right even with cylinder extended to push blade to the left. I don’t think the pitch of the blade has changed. Whenever I got this machine the blade was off of it due to the engine being pulled. I looked at the c frame when I took pictures everything “looks” straight. No twist or cracks where it pins to the track frame. I’m tempted to shorten the rod, maybe I extended it too much. Maybe I’m overthinking it ?
Theres been a fair bit of work done to replace the blade pins . On picture 3 it shows movement of the rod along the pin , its not much but the movement by the time its multiplied to get to the blade tip could make some difference , a couple of collars to stop that movement would fix that . Add to that the difference to the rod length may give you enough tilt both ways . There is no room for a longer ram as the body is close to the swivel mount in picture one so thats more than likely the original . Is the swivel fitted the right way around ?
I have no clue if it is or not. It was already on the machine when I got it. I guess I could turn it around and try it
I’m having the same issue with my D31A-16. I keep making adjustments via the valve on the right side of the “C”. I’m thinking that I have a poor seal in one of the angle cylinders that allows too much fluid on one of the ends. The adjustment process is simple to do.
So that’s some good information there, but I’m talking about the tilt cylinder that tilts corner of blade down left or right. What’s odd about mine I was grubbing mesquites and it was cold that day and it was working just fine tilted to each side evenly until it warmed up. I’m thinking I have a valve problem. Since you have the same machine as me the rod that goes from the top Of the blade to the knuckle it’s shown in picture 3 that I posted. What’s the length from center of the pins ?
Unfortunately, the center link on mine was broken in pieces and welded back together before I got it. I understand that the blade tilt isn’t working properly but the instructions that are in the pictures are how you make adjustments to the cylinders. The valve is on the right side of the C, it’s a square box with multiple hoses going to it and multiple bleeder screws. The valve itself looks like a large bolt head, I think I use an 1-1/4” wrench to loosen/tighten. Are you able to read the instructions in the pictures?
I don't know if you have the same tilt rod setup as my 1978 D31A-16. When I bought mine, only a couple of weeks ago the blade would tilt far to the right but only go back to level to the left. I found the Tilt Rod was bent, probably as a result of using a root rake on the blade. I'll try to post a picture. I have the rod removed an am going to try to heat it and bend it back straight. I'll have to let you know how it works out. Good luck with yours.
It looks more likely that tilting too far to the right caused the bending of the rod . Is the blade fully tilted to the right in that picture ?
No, I tilted the blade to the right to align the tilt cylinder with the opening where you would be able to drive the pin out holding the tilt cylinder in. It was blocked in that position in case I needed to remove the tilt cylinder. I now have the tilt cylinder rod out and I am going to heat it and try to bend it straight with a 20 ton press. You may be right about bending as a result of tilting too far to the right. The previous owner had a root rake put on this machine and maybe he used the rake in right tilt position to try to remove stumps and bent it? He was in the tree business. He tried to tell me that this year machine only tilted to the right? I don't believe that, we'll see when I get the tilt rod straight and get it re-installed. I'll post pictures when that's done. Bob
Well, I removed the bent tilt rod, put it on the 20 ton press and straightened it without heating it. I re-installed the tilt rod and was really disappointed that the blade would not tilt further to the left? It appears the angle cylinder is not pulling in all the way on the left side when angled left, and the cylinder on the right should, I think, be extended all the way out when angled left? And, just the opposite when angled right. The right angle cylinder should be all the way retracted and the left angle cylinder should be extended all the way? Am I correct? The angle cylinders seem to be too far extended and may have caused the tilt rod to bend? If I hold the angle control to the left should the left angle cylinder pull in all the way? For whatever reason the angle cylinders seem to be too far out. I need to hear from someone that has the same blade setup that I have to find out how these angle cylinders work. I gave up today but will get after it on Saturday. How do the angle cylinders work? Does one pull in while the other extends? If I hold the angle control should the cylinders pull in and extend all the way out? Does the extending cylinder push the other angle cylinder in? Should it go all the way it? Because it does not?
Doing more research on this 1978 D31A-16. It appears that the angle cylinders are supposed to be a certain length (1760-1780mm) when operating properly. There is a procedure to bleed the angle cylinders. I will try this Saturday to see if that solves my "no tilt to the left problem". I'm learning!
There is also the possibility that there is internal damage on one or both of the cylinders. Maybe a nut has come off of the rod. If they have been over extended, where are the ports and are there bumpers inside?
Could be internal damage. I'm going to follow the procedure in the operators manual to bleed the angle cylinders and see if it holds. I'll let you know. If I have to I'll pull both cylinders and have them rebuilt. I suppose it could be the control valve too?
The D31 I used certainly had tilt both sides and plenty of it . Are all the rams the original rams supplied with the dozer ? Unless something is bent or twisted , pins worn or undone like a ram piston there is little to go wrong . Going by the picture there is no internal relief valve on the piston . There is a plug listed as number 26 . That ram is made to travel all the way in and out . BLADE ANGLE CYLINDER D31A-16 S/N 25001-UP Komatsu Part catalog k-part.777parts.org
The rams are original. Those are the cylinders I'm having trouble with. It does not go in or out all the way when angling. It seems to push the blade forward working against the tilt cylinder and tilt cylinder rod. There is a procedure to bleed out air in the angle cylinders. I will try that and see if it helps. I don't know if one cylinder pulls while the other pushes out or if the outgoing cylinder is supposed to push the other cylinder in? I will post what I find. Thanks for your reply.
I've pretty much given up trying to adjust the angle cylinders. I angled to the left all the way. The left ram was still about 4" out so I cracked the bleeder plug and cracked the hydraulic line feeding the cylinder and manually pulled it back all the way with a come a long. As soon as I started the dozer up it went back to about 4" out. Neither angle cylinder will pull in or extend out all the way and I don't know how to cure that. I called Linder Komatsu in Wilmington, NC and they are going to send a tech out next week to check it out. It anybody else has any ideas on how to adjust these angle cylinders I would really appreciate that information.
I never had any experience with the one I operated with rams moving on their own . Have you checked for internal damage or the control valve . Oil is moving past something .
You are probably right. I don't want to start removing things that may not be the problem so I guess I'll wait for the tech to come out. It's frustrating. I must be doing something wrong. The machine runs great and it came with a root rake. My son needs this to work his land. Not right away but in a few months. Problem is it's getting cold here now in NC and it's outside. Thanks for getting back to me, I'll let you know what the problem was after the tech gets here.
figure this out yet? I'm having the exact same issue, not tilting left. I use to be able to adjust it by doing the procedure with the block on the right side of the c frame. But doesnt work now. I can do pretty much as you have, but instead of come along I will set the left bottom corner of the blade on a block or something, then tilt blade left, it will suck the left angle cylinder in most the way. But as soon as you go to use it, it goes right back to where it was. Really aggravating trying to grade without being able to tilt it left also. Not sure why it quit being able to be adjusted using that block, unless something inside the block is leaking past whatever goes on in there!
The tech has not come out from Wilmington, NC yet. I've done a lot of other needed work while waiting for him. It wasn't charging, a new alternator cured that. I ordered new headlights (24V LED's). Took the spring covers off and cleaned and adjusted the tracks. Ordered new filters, although the oil looks fresh. I am repainting the dozer, have the ROPS off right now. Almost ready to get back to tackling this tilt/angle issue again. I will let you know what I did or if the tech shows up what we did to get the "no left tilt" issue fixed. That's all that needs fixing now and it's ready to go. Bob, Calabash, NC.
Did this angle adjustment procedure work for you? I am having a "no tilt to the left" problem with my D31A-16 and will try this trick to adjust the angle cylinders. I believe the angle cylinders are pushing the blade forward too much to allow the blade to tilt left.
Well, I think I've tried everything. I still have no tilt to the left. I believe the angle cylinders are out too far and is pushing the blade forward (trying to bend the tilt rod). I angled the blade left and right. The cylinders do not retract all the way and are longer than the required 760 to 780mm when straight. I even pulled the angle cylinders all the way retracted when angled with a come-a-long and that allowed the blade to tilt left but as I ran the machine the angle cylinders went back to where they were and the blade pitched forward and would not tilt left again. Do you think this is possibly a control valve problem or angle cylinder problem or both? I can use the machine as is but I have no blade tilt to the left.
The rams are made to go to the extent of their travel in both retract and extend . You need to determine all of the components are standard for that dozer , if they are they will be the correct length . I see two shades of yellow .
1978 Komatsu D31A-16 Ser. # 25743 Yes, I am cleaning up the machine and used "Cub Cadet Yellow" for paint. These angle cylinders will not retract all the way. They stay out 6 to 8" on both sides. The opposite side does extend out all the way. It pushes the blade forward instead of holding the blade back so the tilt cylinder rod can tilt the blade to the left. They are the original cylinders. The machine has 2900 hours on the clock. The shop manual says you can bleed the angle cylinders and adjust the length of the cylinders to be 760 to 780mm when the blade is straight. I tried to bleed the cylinders according to their instructions but cannot get the cylinders to proper length. I don't know how to "Adjust the cylinders" See the enclosed pictures. The first one is another D31 just like mine. See how the blade is tilted back toward the machine and the angle cylinders are only slightly extended when the blade is straight. My blade is more straight up and the angle cylinders are more than half way extended, pushing the blade forward not allowing the blade to tilt left and causing the tilt rod to bend. Not sure what else to do. You are the first guy to tell me that the angle cylinders are supposed to extend and retract all the way. Mine do not retract all the way. The previous owner had a root rake on this machine and may have abused the hydraulics on the front. I guess I'll have to have a Komatsu dealer mechanic come out to figure this out.
What happens if you pull the top link pin and try and angle the cylinders left and right?
I haven't tried that but if the angle cylinders won't retract all the way I don't think that will affect their motion? I don't know. I can tell you, if the angle cylinders are disconnected from the blade and the blade is tilted back where I think it should be it will tilt left and right. I took the pins out of the angle cylinders where they connect to the blade, blocked them up out of the way and pulled the top of the blade back with a come-a-long. Then the tilt cylinder rod is angled correctly and the blade tilts left and right as it should. I've even thought of eliminating the angle cylinders completely, installing adjustable rods where the angle cylinders are. Setting the length at the 760 to 780mm length as recommended in the shop manual. The blade would be tilted back where the tilt cylinder/rod would work as it is designed. I still may do that. I need the tilt feature more than the angle feature. But, it would be nice to have both.
Something about your whole set up, looks off to me. I certainly wouldn’t be disconnecting angle cylinders but that’s just me.
The pitch looks set far too far toe forward to me , it would have to be set there so guessing they know why they want it there . Looking at the pins on your previous photo's they have been knocked around and badly for such a low hour machine . I notice to that there are two types of pin locks used , that may be standard but looks odd . The only way for a ram not to extend or contract fully is to stop the oil flow. Accepting there are no blocks inside or not enough room to move . When you bled the ram were you letting out oil or letting in air ? An air pocket will stop a ram extending or contracting . Could it be only one angle ram is working ? Both are going to have to be checked either by pulling apart or disconnecting one from the blade ( not the hoses ) and operating the other .
Thanks for getting back to me. The only way to set the blade forward angle is to adjust the length of the angle cylinders when they are straight (both evenly extended, blade straight). Newer machines have a straight bar from the C frame to the back of the blade that is adjustable. That keeps the blade from angling forward. Mine has a knuckle and a tilt rod that goes diagonally to the blade. The tilt rod on mine will not keep the blade from pitching forward, it only tilts the blade left and right. The shop manual says the distance from pin to pin on the angle cylinders should be between 760 and 780mm when the blade is straight. They are much longer than that. I think the only way I'm going to find out what is going on is to get the Komatsu service guy here and let him diagnose it.
That rod is not original , is it the correct length . There is a range of 20 mm difference between Komatsu's specs , what is your measurement . If nothing is bent , worn and is standard original the measurment should be the same . The rod should not affect the pin to pin measurement . The one I had was set up like this and it's rod had thread showing but was welded solid .
They are magic when they are working right . Sets the dozer into a class of their own .
I'm going to take a video of the blade in motion so you can see what it does. That might explain what's happening. I appreciate everybody's help with this. Bob
OK, shot a video. It shows the angle cylinders do not retract all the way. They seem to extend all the way, left and right. You can see how the angle cylinders keep the blade pitched forward not allowing the angled tilt rod to tilt the blade to the left. I don't know how to adjust the angle cylinders to retract all the way? Any Ideas? this is a 3 minute video, I don't know if this website will accept a file this big. No, I can't post that video,just be too long? Give me an email address and I'll send it. Bob
Won't let me post a video?
I would leak test those cylinders, as all other testing becomes irrelevent if one of them is by-passing inside. Might have to install an extention hose to be able to run by pass oil into a pail. Had one just recently that the rebuilt cylinder was completely gone and the one that was weeping was okay. 3 cylinders to tests and after that you can start bleeding, otherwise the first time it hits something firm the cylinder will retract. If that does not reveal a leak then you need to pressure test each line for how much pressure there is. Simon C
In your post number 24 you said the rams won't extend fully but now do , has something changed . Ram going fully extended while the other not fully retracted probably has something to do with keeping to volume of oil moved the same . The angle rams won't affect the pitch , any force from the blade against them from pitch would bend them , they should have a swivel ball in the ends of them to stop that . The little solid rod is for pitch .
Simon, The angle rams do seem to extend out all the way but do not retract all the way on either side. I wish I could post this video. The tilt cylinder works fine, travels both ways to the limit. I have no way to pressure test the cylinders. I think I can rebuild these angle cylinders fairly inexpensively right on the machine. Maybe that's next. The picture I enclosed is not of my machine but is a machine exactly like mine. You can see the blade tilts back and the angle cylinders are not extended very far with the blade straight. My blade is straight up with the top of the blade even with the cutting edge. Something is not right.
You probably have oil leaking from the rod side of the piston to the barrel side on one or both of the angle cylinders. This is throwing off what the control valve is allowing the other cylinders to do. This would explain multiple people having the same problem with the lack of tilt and bent con rods. The system is designed to coordinate the length of the 3 actuators with respect to each other mechanically. The adjustment valve procedure shown above sets the baseline relationships. If one of the cylinders isnt sealing, the actuator relationships are thrown out of balance. If the seal only leaks in one direction, bent conrods and confused diagnoses might ensue. I'm not a trained mechanic but I have looked at your pictures and thought much about how this Rube Goldberg contraption might function. And fail.
You need to add your video to a website like YouTube. There are quite few video sharing sites that you can use similar to YouTube. After doing that post a link to it in your thread that you have here.
I will do that. Thank you
OK, I added a video to you tube. I'll see if I can list it here. It shows the angle cylinders not retracting all the way. The blade is pitched forward not allowing the tilt rod to push the blade to the left. If the blade was held back by the angle cylinders it would push to the left. angle/tilt problem
Tinkerer, thanks for telling me how to add a video. I'm old and not in good health so I appreciate the advice. Just trying to get this machine working correctly so I can help my son out on his property. Bob
Good video. I will have to watch it more later but there is something wrong but not sure where. What is the major complaint? I see a problem with the tilt cylinder not tilting past center and that linkage is a bit screwed up and unfortunately being off kilter up top pays huge dividends on the tilt cylinder stroke. Not sure what’s original or not on the cylinders.
Thanks for getting back to me. I believe all the components on this machine are original. Only 2900 hours on the clock. The major complaint is that the blade will not tilt left. The tilt cylinder travels full stroke in and out but because the tilt rod is pointing almost straight forward it will not tilt the blade to the left. The angle cylinders are pushing the blade forward, they are too far out, not holding the blade back to allow the tilt rod to push to the left. When you angle left and right the angle cylinders do not retract all the way. They seem to extend all the way out but will not retract all the way in? I read in the shop manual it says to adjust the cylinders to 720 to 760mm (pin to pin sum of both sides) but it doesn't tell you how to do the adjustment. The previous owner had a root rake installed on this machine and may have abused the blade trying to root out stumps. This may have damaged the angle cylinders pulling them forward and causing internal seal damage. If I knew how to adjust the angle cylinders I would try that and if that doesn't work I'll install new seals in the angle cylinders. Not sure what to do? See the enclosed picture of another D31-A just like mine. The blade pitches back and the angle cylinders are not out very far at all. The tilt rod is diagonal but more left and right rather than forward like mine is. This is not my machine.
The swivel below the tilting cylinder could be grabbing some, causing part of the problem. Now that I have seen your video, those two angle cylinders would be easy to by-pass test. Stroke one cylinder to the end, disconnect the rod end hose and put into a pail and restart and Rev the engine up and try to stroke it out further on the same cylinder. If oil pours out the disconnected fitting, the cylinder is junk. Then hook back up and test the other cylinder with the rod pushed out and fitting disconnected the same way. Just to let you know, I tested a guys tractor that would not steer, he had changed the orbitol valve and wanted me to change the pump. I would not without testing the pump pressure which was full. He insisted I change the pump, I disconnected the tie rod ends only to find out the shaft the tie rods were connected to was seized solid. Unseized and greased and all fixed. Moral of this true story, test those two cylinders first for free, then test the 3rd tilting cylinder for by- pass and make sure the swivel pin on bottom is not seized. Would be good to get a Komatsu T- fitting to check how much pressure the machine is putting out before buying any parts. If all that passes you will have to do the bleeding procedure that was listed up above. Simon C
The manual shown in this thread does tell you how to adjust the cylinder length. I agree it isn't easily deciphered, especially to those of us not onsite. Are those the instructions you are following or do you have your own, different manual and instructions?
I don't think the angle rams have anything to do with the problem and it looks like they are fine . They just float and are there for the ride . There appears not to be enough movement in the tilt ram . The motor loads up when all the rams are extended which is good .
OK, next fairly warm day I'm going to do the By Pass test Simon C recommended (above) and will try the bleed procedure again. This tilt problem is the only thing left to fix before I can use this machine. Been working on it for a month. I will post the results here. Thanks for all the info guys.
Simon, were you able to adjust your angle cylinder length using the bleeding procedure posted? I read that Plug 1 is actually a large bolt head (maybe 1 1/4") I didn't realize that was a bleeder. I was opening the small 1/4" square headed plugs. I'm going to try that procedure again today.
I just read the bleed procedure. The cylinder leak test is the same on basically all cylinders. I'm guessing the tilt cylinder will fail the test. Just my guess. Let the tests determine the next direction. Simon C
Simon, I tested the cylinders as you said and no oil is leaking by. I then followed the procedure to reduce the length of the angle cylinders by opening the large bolt (I didn't know that was a bleeder) and the two square head bleeder bolts on both angle cylinders. I tilted right and angled left and right and the angle cylinders sucked all the way in when angling both left and right. Video Enclosed. Now, I can probably get them to retract even further but right now I have left and right tilt and left and right angle working fine. I might be able to get a little more left tilt but it's fine for now. Now I have to put it to work to see if it's going to hold. But at least I know what to do if it needs adjustment in the field. Thanks Again, Bob
I can probably get more left tilt but at least I can get to work with this thing now. After the angle cylinder adjustments. That's my wife on the machine. Thanks Simon
Always good to test the cylinders first as no one can see inside a cylinder to see if something is by-passing. Pushing the rod out with fitting hose off also bleeds all the oil out of the rod end at the same time. Gives a better start to bleeding. No money spent other than a little oil and keep moving on. Thanks for posting the last video. Simon C
Sometimes because of a cylinders set-up the only way you can get all the air out is by disconnecting the rod end allowing the rod to stroke both ways full distance while fittings are loose, one at a time to get air out. Simon C
I just fixed mine with same issue, on the right side c frame is a junction block on the side of the junction block there is a plug that I think is 30mm. Loosen this plug but don’t remove it, it’ll be 5-6 turns out. Lift blade with engine running angle blade all the way right once it’s right tilt blade to left. The blade won’t move just the cam arm. Depending on how bad it’s out you may need to do this twice. Once blade cams all the way left. Tighten that plug, and reset blade to center. Measure pin to pin on BOTH cylinders the sum of both measures should be 68.5-70”. If they’re not do again.
Does anyone have the part number for the tilt link that bends?
Probably can find it , can you show a picture of it and the Dozer model number
Model# D31-16. Serial# 25555. I can't seem to get a picture to attach. It's the link that comes off the top of the blade and hooks to the tilt cylinder link. Thank you
Is it the rod , number 8 . Part number 114-72-21720 same part is used on the "P" model
Thats it, thank you.