I have a 1979 Komatsu D75S-3 track loader that I was using when all of a sudden reverse got real weak and slow? Still moves, but not like it should in reverse. No problems going forward. Hoping someone on here could get me started on what to look at first. Machine doesn't get used that much it sits a lot . Oil and filters are fresh. Anyone on here know anything about these machines and what I should look at first? Any help is much appreciated!
Any ideas?
Can anyone help me with this? The weird thing is sometimes it has reverse full power other time it doesn't . Machine sits a lot. The last time I drove it I just tried to keep going back and forth to see if that helped which it didn't seem too. Transmission has fresh oil and filter.
Anyone know where I could find some information on this?
looks like WE are out of luck with these old loaders. been watching your post for a while. i have one but havent had any major problems with it YET. hope someone gives u an answer. i do know to shop around for parts the dealer thinks they are made of gold. track tensioner seals i bought a complete kit for less than the price of one outer seal and it had the same part numbers on the seals.
Jughead- Where did you get your parts at? I bought aftermarket seals and U-packing for dump cylinders and I haven't been happy with them! Wish I would have paid the money and bought OEM. I had a hose break and lost my transmission oil. Not sure if that caused this problem or not? I would have thought there would be a mechanic on here, but guess not. I've got a lot of money invested in this machine hoping to get this problem fixed. Thanks for replying!
found them on the net. been over a year. memory aint much any more will try to find the invoice and let you know. wish i could help on trans but i cant.
You can buy a service manual and a parts manual here: http://www.ebay.com/sch/i.html?_fro...u+d75+manual&_nkw=komatsu+d75+manual&_sacat=0 They will be a big help in your future. An operators manual wasn't listed, but one will show up for sale on there. Keep looking.
Thanks D9GDon I have them! Not sure if your familiar with Komatsu's manuals they leave a lot to be desired. Not even close to Cats. Went out today re-checked the machine tranny oil was low. Going to retry it soon
Bring this subject back up because I'm still having issues. I have reverse but it's weak and will sometimes stop. If I go back to forward then back to reverse it helps and if I get a full head of steam in reverse it seems to work properly. Does anyone have any ideas?
I had a problem a bit similar to that where my old 941 Cat loader would sometimes loose it's forward motion when in gear. If I put the shifter ahead to neutral & back again, away it would go. We changed the transmission/ bevel compartment oils, filters & cleaned the screen & it worked fine after. I suspect the dirty screen was the culprit, as it was plugged.
I did re-clean the strainer. It was not bad at all. Tranny has new oil. Maybe I'll change out the filter even though it has low hours on it. The machine actually got better the second Day I ran it which is encouraging to me.
Where and what kind of hydraulic pressure tester do I need to test the transmission? Anyone know know where I can get a good tester with the fittings I need that's not to expensive?
you need 40 bar gauge and 1/8 BSPT fitting. You can test the trans. pr. on the trans. filter on the top cover, remove the plug on the cover and measure. there are two filters side by side they look the same, located under the trans. and steering pump. Just follow the line and you find out wich one is for the trans.
Hopefully you do not have the same issue as I with my old powershift. The trans in my Allis is ancient, seals are drying out, shafts are wearing at the seals so bypass fluid is growing where pressures are dropping so hard to keep the clutches engaged. I have a spare so am looking to open it up to see what if at all I can do to get it up to speed.
Hydraumind- what is 40 bar equal in PSI please? Is there a guage you recommend and where can I get one please?
I had contacted Lucas oil company about this and they told me 10% Lucas oil engine stop leak would help. They said it would recondition seals and boost pressure.
40 bar is almost 600 PSI, you gonna measure around 20 to 22bar which is 300 to 330PSI you va also use a 900PSI gauge. Anyway try to check this link: http://www.hydracheck.com But before you should check if the plug on the top of the filter is indeed a BSPT or metric, this machine is old
Eroded rubber/synthetic shaft seals, hardened elastomeric components, grooved shafts worn from the pressure of seal contact won't remedy with Lucas stop leak, may actually gum things up that were working. Getting to the bottom line as to shift and clutch oil pressures will bring it into the diagnostics level you need to be and how to align to make good long term repairs. I was a mechanic on these machines in the 70's/80's into the early 90's when the electronic controls started showing up and out big time, too many were in the process of modifying where I had to go back and find then fix screw-ups they did not want to pay for as they knew they were right and I was incorrect as to their handiwork being a cause. I like old machines with hard part mechanisms hard linkages and for the most part longevity.
Do you have any ideas what might be wrong with my machine?
Not really without seeing the hydraulic pressures and comparing to the service manual which I do not have access to anymore. Most of my repair manuals were either sold or donated years ago thinking I would not need them any longer. Lower than normal range shift pressure in a single range indicates poor seals, in all ranges is indicator of system losses such as weak pump, pump sucking air (possibly intermittently) or blown seal at a control head, lack of pressure on a clutch pack pressure can be either seal ring failure, housing eroded at seal ring, eroded clutch facings allowing excessive movement with fluid bypass at edge of apply piston. If all pressures in normal ranges and still slips on occasion I would suspect clutch pack hanging up in housing where the loose discs are slipping, this can happen as the teeth of the clutches work in one spot for a long period of time cutting grooves at the housing teeth then as the plates wear they begin to hang on the rough surfacing and not properly engaging but that would be a absolute longshot. My own dealings with an aged machine I replaced a number of hydraulic pump feed lines, used high pressure large diameter and hard to position hoses as all I could get locally, ended up with a suction line sucking air so badly would not pull oil from sump, re-installed old line and was fine but still need to replace it at some point just not certain with what as yet.
This happened quick. Ever since I owned the machine it never would really go in any gears except First in either forward or reverse.
When I first got my Allis it had 1st Forward strong and 2nd reverse which shortly failed and 1st reverse did work enough, spare trans went in where 1st and 2nd forward are reasonable, pressures are a bit low but in band, 1st rev is good but 2nd rev is real strong with pressures a bit higher than forward so I know the shifting seals in the housings are going. When I swapped units the old one was sitting aside the tractor I put are to the shift ports, massive leakage into the main case from the shaft seals region, mine shifts thru ported oil riflings in the actual trans shafts so either busted shafts(doubtful) cooked off worn out seals. Previous owner ran it leaking and low on trans oil, hydraulics for steering clutches also had to be reworked to keep it steering as those leaked so badly.
I'm thinking now machines weak in forward to just worse in reverse. I have a pressure guage kit coming.
Guys is there a aftermarket transmission pump that's of good quality?
Hydraumind- Am I able to do all checks on top of the filter housing? I'm thinking maybe the Transmission Pump is weak.
Yes you can. Do the check on all speed Fr. and Rev. at low idle and high idle, cold and warm oil temperature, then let us know what you find. It is very easy to remove the transmission pump on those machines, you do not even have to drin the oil, so remove it if you have a doubt and check the inside
Hydraumind- Are these machines known to have pumps go bad like I have read do you know? Do you know of a good aftermarket brand if I need a new one? The OEM one are prices ridiculously high. As soon as I get some tests done I'll post the results on here. Thanks for the help!
These were great machines, they do not require any particular care. Anyway, you can check ETP company (Europe tractor parts) for aftermarket parts, they are located in italy and they do high quality parts for those machines
Hydraumind- I got some pressure readings today. 75 psi cold at idle Forward and reverse 125 psi with throttle forward and reverse cold 75 psi hot with throttle at idle it was barely showing anything. Now the weird part if I went in reverse at idle and then throttled up it seemed to work fine, but if I had throttle open and went into reverse it didn't want to go. When I used steering clutch cold my pressure was 300 psi when it got hot it went down to about 260 psi.
Steering has a seperate pump. In fact, you have tandem pump, one for steering and the other for transmission. Anyway, I think you have a control valve problem, so my advice is to remove the transmission control valve and check if some spool are stuck, clean very well and change oring then install again. Try also to remove the trans. pump and take a look to it, if it is clean just change seal and orings.
Thanks Hydraumind appreciate the help.
Hydraumind- I screwed up on my checks. I was attached to the steering filter housing. After pulling the floor plan today the rear filter housing goes into the transmission control panel. I messed up. I'll have to recheck pressures.