So this week at an auction we picked up a cheap komatsu 3000# forklift for the shop. the thing works fine for about 5 minutes, then it wouldn't move. After a rest/ cooling period it works again. I also whines more or less depending on whatever. The oil level in the box is right between the marks. I think I'm going to drain the tranny and put some fresh oil in it, should I put ATF, regular transmission oil, hydraulic equipement oil or what ? The tranny has a torque converter and a forward/ reverse lever as well as a clutch lever. I dunno if it has more than 1 forward speed.

please let your input flow :)

Thanks for the help :D :beer:,

http://toy4x4.free.fr/passiont/photos/fg14d/tranny.jpg

single speed, not sure on the fluid in that one buy ours uses atf. call a fork lift place with your #'s.

What motor is in it? 4cyl nissan?

Use tractor fluid, like TF-1. You can get it at a forklift dealer or probably a farm supply store. Also change the filter. You may have a bunch of clutch material contaminating the tranny and when it circulates, it clogs the valve body. You may also have an "inching" feature on there and that may be hanging up and not letting it out of neutral.

That's about the gist of what the forklift mechanics here have told me, or at least the best I could do to translate it over to you. Good luck!

OK, thanks guys. I will look into it some more. I also called a friend who is in the auto trannies tech, he also suggested ATF or similar, and told me the oil quality and lever are very important. -I'm an absolute ignorant about auto trannies myself, I may have spent 15 minutes total driving them in my whole life- There doesn't seem to be a filter on the tranny, but I will double check. I'll change the fluid tomorrow and see what it makes.

Thanks for the tips guys, I hope the problem is not too bad, well if it is I guess it'll be time to learn some more machinery tech !

:beer:,

Jim, the engine is a toyota 4cyl gasser, it starts and runs pretty damn fine :)

you could have a bad pump, or pump pickup I would try fresh oil the if you still get the same thing maybe try to over fill it (might fill past a crack in a pickup tube and suck oil) but the whining shonds like pump cavitation or could be the pump by passing

usualy when a machine works good cold but fades away its a sign of a bad pump, the oil gets thin and just churns in the pump insted of doing work

Thanks for the input :D

I got a closer look at this stuff, the tranny actually has 2 long lines going to the back of the truck to an oil cooler that I first thought was for the hydraulics. My friend explained me that there could be a thermostat in the tranny that would open when the oil gets warm, and the T/C could then starve due to the low oil level when the oil goes into to the cooler. The whining noise definately comes from the torque converter, and when it's not working the engine just feels like it's freewheeling, which would match with the T/C starving therory ?! I drained the oil, there's about 5qts of brown/ blackish oil that came oil, smells a bit burnt, the drain plus magnet had a bit of thin black/silverish powder on it that really doesn't look too bad. I'll take a funnel and go fill the thing with ATF after lunch, my friend told me to fill it through the gauge hole since I'm not sure what the big, fill plug looking screw ontop of the box is, could be a piston/ spring/ troublesome thingy behind :rolleyes:

http://toy4x4.free.fr/passiont/photos/fg14d/DSCF1289.JPG
http://toy4x4.free.fr/passiont/photos/fg14d/DSCF1290.JPG

Sounds like your friend has you on the right track, I never thought you could ues shit to lube a trany but it looks like someone tried???

it doesn't really smell or taste like shit :D

OK so I dumped some fresh ATF oil in, first 6qts, a little more than what I took out (the quantity of oil that was poured on the outside of the tranny, and on the floor is marginal.) It didn seem to help a lot. It still would quit moving after a while. Then I added another 2.5qts or so, now it sounds smooth and doesn't whine anymore, but it's still not going anywhere far. Sometimes it feels like it is going to take off, sometimes it really takes off after a couple seconds accelerating, sometimes it doesn't. The more I keep trying the less it works. The oil level is about 1/4", maybe a bit more, above the dipstick zone. :confused:

soulds like the pump is toast, similar to the pump in a standard auto. You could try checking the line pressure, as you might have piston seals that are bad. But with the "fade away" it sounds more like a pump

OK, thanks for your input. Is it possible that thicker oil might make it work better ? Oh well I'm not trying anything like that before I find the factory recommendations anyway. Looks like I'll be looking for some education on this tranny style before I look deeper into it...

OK, thanks for your input. Is it possible that thicker oil might make it work better ? Oh well I'm not trying anything like that before I find the factory recommendations anyway. Looks like I'll be looking for some education on this tranny style before I look deeper into it...


its not a big deal to try thicker oil, you just wouldnt want to go to thick and you wouldnt want to keep it out in the cold and then try to fire it up and go to fast befor the oil gets circulated good

OK do you think I could try to mix some 90wt gear oil in the ATF ? Or maybe 15W40 ? I dunno what the stock dexron viscosity is :confused: Right here there's not a lot of choices for ATF...

thanks for the help !

BTW I tried to move again today, well it sounds very smooth but isn't really going anywhere even when cold. Could it be too much oil from the overfill ?

well you gotta look at it like this

if the pump will not deliver pressure the clutch packs will not inguage

if the pump will not deliver flow the TC will not work

if the pump makes some pressure and little flow your clutch packs might be inguaging but sliping (eating themselves up)

I would drain the atf into a CLEAN pan so you can see what comes out with the atf I would also get some "tractor hydraulic oil" rated for hydrostatic transmissions or some "30 wt transmission drive train oil"

some people will freak out about oil and say "only put whats supposed to be in it" butI have seen that with different equipment which use some of the same parts they call for different oil

Gradall's use mobel424 for hydraulic (there hydrostatic drive that work off of 5K psi pressure for the drive), for the front axle and for the rear planetaries

Lulls use 90wt in the axles and 90 wt in the planetaries they also call for 30wt TDO (trans-drive train-oil) but work fine with 15W40 in the trans (for thousands of hours, following recomended service intervols)

Cats forklifts use 30wt tdo in all drivetrain parts


mostly you have to go somewhat by what the maker recomends but LOGIC plays a key too

OK, I have the same logic, I think this all makes sense. I hope I can find some manufacturers specs and recommendations. I'll start calling around if they don't answer my emails. Thanks for the help !

:beer:,

You can screw around wasting time on fluid changes, but it won't change the fact that the pump is toast, and only a rebuild will fix this thing. There's no cheap fix for a bad hydraulic pump. It's probably scored, from dirty fluid. It looks like it never had any maintenance based on what you took out of it.
If it was me, I'd pull the pump, take a look at the parts. I rebuilt my tractors hydraulic pump on the cheap, surface ground the rotor mating surfaces a few thou to take the scoring out, and put a new cartridge in. Worked like a charm.

You can screw around wasting time on fluid changes, but it won't change the fact that the pump is toast,



this is true BUT depending on how much he palns on using it thicker fluid might get him by for a week, month, or a year, it all depends on factors that you cannot tell with out taking the unit appart. Or with out trying it, and I like for the most part to try the cheep fixes first, especially when it involves pullin a trany.Sure doing the "maybe fixes" might do more damage to the tranny But they might not also??


bottom line is you can eather fix it right, or try and make it get by, each one has its ups and downs. Only you can choose whats right for you.


:flipoff2:

Thanks for your input guys I really appreciate it, keep it coming please. I'm a complete ignorant about auto trannies so I could use every remark. ;)
Can you pull the pump out without taking the whole unit apart ? I'll look into it some more, and hope I can find a repair manual for the box. :rolleyes:

I'm definately not going to use the truck 24/24 but I can spend a little more money to fix it and make sure everything is right for the long term.

Thanks,

if the trany and axle are mated together it might be easyer to pull the engine

I havent worked on many "slab" forklifts but I have worked on very many other types

the axle is kind of bolted to the tranny as far as I could see. Do I have to tear the tranny apart to get to the oil pump ?
"slab" WTF ?

at this point I'm leaning towards maybe trying some thicker oil to try to get the thing going while I'm documenting and researching about fixing the tranny for good. Would there be anything else to touch in the tranny besides gaskets and seals while I'm in there ?

thanks,

the axle is kind of bolted to the tranny as far as I could see. Do I have to tear the tranny apart to get to the oil pump ?
"slab" WTF ?

at this point I'm leaning towards maybe trying some thicker oil to try to get the thing going while I'm documenting and researching about fixing the tranny for good. Would there be anything else to touch in the tranny besides gaskets and seals while I'm in there ?

thanks,


the trany pump should be driven by the end of the torque convertor and would come out from the front of the trany. remove engine, remove TQ, remove pump, rebuild, reseal, reinstall, fawk it up again!


and "slab forklifts" usualy have hard rubber tires (sometimes air filled) and are strait mast, sometimes are duel fuel or batt powered, and are made to work on hard pack ground or a concrete slab, and dont like being offroaded

rough terain lifts are just that, there made for RT :D

OK, thanks I'll try to lay my hands on a repair manual for the truck.

This one has some mild pneumatic MT tires, I think it could do OK on hard gravel stuff :) no difflock though :D

OK so the importer says I should use standard 10W CD gear oil. From what I could find on the web, it looks like it's about the same in terms of viscosity as dexron ATF, just a way lower standard regarding to chemical additives and such, is that correct ? I'll see if they will be willing to sell me a repair manual when the local dealer wakes up :\

OK, not much to update about here, but I thought I would share what looks like a good tech link for hydraulic stuff... http://www.hydraulicsupermarket.com/technical.html

cheers,

A couple things, not all easy to explain;
First, the pedal on the left (what you'd call the clutch) is called the inching pedal. When you press it, a variable valve relieves pressure on the trans clutches, allowing the operator to speed the engine for hoisting while moving slowly. Rough on tranny, but they're made that way. First check that the adjustment isn't too tight/loose; some pull, some push. Shifts from neutral should be crisp when the inching is disengaged.
Next, it's very common for forklift torque converters to smoke the stator clutch, which smokes the fluid, which smokes the clutches.
The trans fluid should be checked while idling, like any automotive automatic. If the whine gets better with more fluid volume, note whether you're low when running. Forklift transmissions are very whiny compared to automotive even when they're new. Sorry to say, but heat related transmission issues are nearly always the result of worn out parts-pump, clutches, seals, etc. If you have to get into the trans, it's relatively easy-yank the motor, yank the tranny. Everything is much more straightforward than in a car, and cheaper to have professionally rebuilt than at an auto shop. Komatsus are tough bastards-how many hours on this unit?

Thanks for the tips.

The inching pedal linkage seems OK. On this truck when you press the inching pedal the linkage is made so that it also pushes the brakes.
I tried some thicker oil, it doesn't seem to help. At some times it takes off after you accelerate for a couple seconds. if you push the inching pedal then you have to start over and wait again. Fluid level is OK, doesn't seem all that different between cold stopped and running or hot. Now I think I will have to take it apart eventually. then I can see what's up with this and what needs to be done. I'm thinking pump, seals, clutch packs maybe ?
I'll call the local dealer for komatsu and see if they would sell me a repair manual :confused:

The truck has something like 5500 hours, the hour meter still works.

Sounds like you have plugged passages, and looking at the fluid it's a good bet. I'd put straight cheap ATF in it and run it for a bit-try not to put much power through it while it's not locked up, and if it won't engage firmly, or drops out when hot, stop. You may be able to rinse some of the crap out, though you have better odds at the casino. Disconnect the inching pedal to be sure it's not being held partially open. After all this, you're back to the beginning-a rebuild.

OK I've been doing more research, I kind of been doing what you're saying, elacruze, trying to wiggle things out, from the beginning, it doesn't seem to improve much. The inching pedal and linkage looks firm with no play. I've checked the oil temp, it really isn't that warm, I'd say barely over ambient temps when it quits working. Also the forward gear quit just a little before reverse today. I'm just more and more confused with this, the more I think about it, I feel like it could be worn pump, worn clutches, dirty valves, bad converter, all this in an OR or AND combination :confused:
As soon as I have a manual I'll open it and think about a complete overhaul. Hopefully a couple $$$ later I'll be good to go ?!

thanks,

I asked the mechanics at work(United Rentals/bunch of forklifts)They both said torque convertor.

How well do the forks work?
Lift well loaded?
What happens when you lever the mast all the way forward and continue pushing the lever?
Trying to discern if the pump is pooched or not.

I'm worrying about the tranny pump, the hydraulic power pump seems to works fine, the mast and power steering work perfectly.

torque converter, mmmh doesn't sound too good... My friend told me sometimes/often in the industrial equipment they use a "coupler" instead of a torque converter, similar principle, but without the fancy freewheeling rotor in the middle or whatever there is, that kind is supposed to be pretty bombproof... I dunno how to tell a TC from a coupler, and how to check if it's good or not though ? As soon as I have power and lighting in the shop I'll try to pull the engine and see from there I guess ?!

thanks

just because the inching pedal linkage seems firm with no slop dosent meen its adjusted right

OK I'll look into it more tomorrow and post the results ;)

thanks for the help,

OK it seems like you guys were on the right track with the inching pedal ! I disconnected it, it started right away then stopped, it was a lot firmer than it ever was. I pulled the floor again, felt and played witht the inching rod directly on the valve box, it seems like it was only adjusted to push halfway through. I cycled it back and forth a couple times. The truck then ran and took off firmly in both forward and reverse. I reconnected the pedal, and after a while it quit again. I'll take the linkage assembly apart for cleaning and greasing, and try to adjust it right and we'll see how it goes from there. I'll put regular ATF back in, I think the TC is way too fast with thick oil.

Thanks for the help, I might be getting there :) -hopefully-

:beer:,

I'm not done yet. I adjusted the linkage, the way it was set up would only push the inching rod into the valve box halfway, and would put the brake pedal almost immediately (combined linkage). I kind of fixed that, it now feels firmer, and seems to work a little longer that it did, and takes shorter to "cool off" or whatever happens, but it still quits working after a while. I think the whining sound comes from the clutch packs, it sometimes stops when I push the inching pedal, or when the truck gets moving. Also the torque converter seems to bite very early for my taste (I switched back to regular dexron), when in gear if I don't press the inching pedal it moves even when not accelerating, like there was little or no slippage ? How can we usually tell a bad converter ? As for the tranny itself, I'm thinking about bad clutch packs/ discs/ bands whatever it is, it would fit in a scenario when the misadjusted inching pedal that doesn't inch all the way and pushes the brakes early in the throw, combined with a somehow locked up converter would lead to a premature wear of the clutches ? What do you guys think ?

thanks

Now you're getting somewhere. Disconnect the inching pedal linkage altogether. See how the tranny functions like that. Note which way the inching spool sits-in or out, to help with re-adjustment. The truck should creep in gear, the tranny is locked in and you're on the converter just like a car. Testing converters is much harder, you need the factory manual for specific test proceedures. Generally, a smoked torque converter will either engage at very low rpm and bog the motor, or allow the motor to rpm but the truck is extremely sluggish. If it'll spin the tires at any time, the TC is good. If it won't, it still doesn't mean the converter's bad. :p
I assume you don't have a pressure gauge to check tranny pressure with? If so, I can ask at work and somebody can find out. Likely it's between 200-350 for the trans.

Well, here is what I did with the inching linkage. At the start it was setup so that pushing the pedal all the way would only push the inching rod halfway through the valvebody. It only used to travel about the first half of its stroke. I adjusted it so that at rest the rod would come out all the way it could, just as if the linkage was disonnected altogether, and when the pedal is fully pressed, the rod is pushed in along all the useable stroke that I could feel. Now the pedal has a very long stroke, the the inching system travels all the way. (The inching system is a push system, when everything is disconnected it springs back out as if there was no pressure on the system. I think some other makes work the other way, so I'm not sure what we're talking about here ?)

As for the TC, I'm not sure about this, I'm really NOT familiar with autos. When I let the inching pedal go it moves immediately, like there was almost no slippage, I'm not sure it that's right or wrong, it feels like it is engaged all the time :confused:
The tires spun when I drove the truck onto the trailer ramps, and also when I drove it onto a couple wood blocks to give me a little roome underneath to change the oil.

I have a pressure gauge, but I'm not sure of where I should plug it in, and what/ how to test. I'll have a closer look and write down how the different port on the valvebody could be labeled, and take a couple more pics...

Thanks for the help!

:beer:

OK, todays update :D

I finally got around to work on it some more. A friends dad who works in forklifs and equipement repair was hanging around last weeks, he gave me a coupple ideas and promised some help if I needed. So I took the valvebody assembly off and apart, it seemed fine, (no rubber seals in it, all the distributors are precision machined only.) so I cleaned it out, it wasn't dirty anyway, cut a new gasket and bolt it back on.
The interesting thing is the oil filter that I finally found out. I lifted the truck and put it on wood blocks for a clean oil dump. Both plugs are drain plugs apparently. There is a small plate bolted on the side of the oilpan in the bottom, that you almost can't see when the truck is on the ground. I didn't think there could be a filter behind this, the location and accessibility made no sense to me, I took it off anyway and the filter was there. Literally clogged with a soft black mess. Needless to say I cleaned it off real well. Today I put it all back together and dumped some fresh oil in it, the damn thing flies :D I drove around in the shop for a good 10 mins, and the thing never failed. No more whine either. I'm stoked :D

Thanks for the help and tricks guys, I should kick my ass for not finding the oil filter before, oh well. I hop there is no hidden issue with the tranny but I'm pretty damn happy for now, we'll see how it goes.

:beer:,