Clark 668C winch

Clark668C · June 10, 2017, 10:52:07 AM

can someone tell me what kind of fluid the W400 series winch operates on? I have a beautiful 1978 668C and the winch is slipping on heavy pulls (30 000 lb) logs? Its rated to pull 40 000 with the drum empty and easy yarding uphill? Just wondering if it needs new fluid? There is also a bit of black looking oil seeping occasionally out of the breather on the left side of the winch? The control valve used to operate the winch gets very warm with heavy use and not sure if that is common? Any help with this would be greatly appreciated very much.Thanks

treeslayer2003 · June 10, 2017, 05:34:38 PM

assuming you have a clark winch, it gets fluid/pressure from the transmission. sounds like your pressure may be a little low. but they will stop pulling at a certain load. i am also assuming a 668 works the same as a 666.

Clark668C · June 11, 2017, 10:40:46 AM

yes its a Clark winch and its burping oil out of the breather and the oil is blackish in color so I don't think its tranny fluid because of its color. I'm wondering if there is some kind of other type of fluid the system is operating with? Maybe a type of gear oil? Its not leaking any where else that I can find. Will an air lock in the system cause it to discharge the oil from the breather? The tranny filter hasn't been changed in awhile and would this be causing some of my issues? Thanks for the advice

treeslayer2003 · June 11, 2017, 11:27:44 AM

there may be gear oil in one side......honestly i have never had to mess with one, they just work. is it possible rain water got in the gear box side and over filled it? be careful what you do here, don't add gear oil where it can get into the trans.

Fether Hardwoods · June 11, 2017, 12:25:24 PM

This is a link to where you can get all the manuals you need for Clark skidders for free, it appears that just like Treeslayers and my own 666 the 668 also uses the same oil for the trans, converter, and winch, so my guess would be a bad seal inside the winch causing a small amount of oil into a spot it should'nt be and picking up dirt and debris somewhere before being pushed out the breather.

http://www.alliedsystems.com/pubs/pubs.htm#

Clark668C · June 11, 2017, 01:27:41 PM

Thanks treeslayer, the skidder was parked for 3 years and was never touched till it was given to me. I'm not much of a mechanic but have become very interested with the functions involved with this system. Will check for water and maybe the poppet valve in the breather.

Clark668C · June 11, 2017, 01:33:02 PM

Thanks fether, I have been using allied' s website and they have a lot of great info for our machines, just haven't found any info regarding my issues yet but will continue reading and hopefully find what I need.

kiko · June 11, 2017, 10:04:00 PM

The winch uses the same oil as the transmission. There is a clutch pack inside the winch that is a activated with transmission pressure. There should be a drain hose that goes through the hinge to the transmission case. So I would suspect that drain hose is blocked and allowing the winch to over fill. We used to add transmission fluid at the winch because it was much easier to pour there than in the cab with the floor board flipped. You don't want that burnt oil going back into your transmission. The clutch back is likely worn. Need to get the manual for than winch before breaking into it far. The clutch is strait forward. But the brake has some big springs that can blow apart on you if not disassembled and reassembled properly.

Clark668C · June 12, 2017, 10:41:03 PM

Thanks Kiko, would you remove the breather to add the ATF or did you use the drain tube? I have been trying to bleed my brakes the last day I was pulling wood and wonder if there was air in the system that could be adding to my winch slipping? With the exception of the midmount brake everything else runs off the same system(brakes trannny & winch) Is it hard to find parts for these winches? My model number is WD-412

treeslayer2003 · June 12, 2017, 11:19:17 PM

you don't add fluid to the winch, it is in the transmission circuit. if the trans is full the winch is full.

kiko · June 12, 2017, 11:27:47 PM

Yes, but you can add the transmission fluid through the breather on the winch. I don't know how to direct to an old thread started by nblogger in which oldseabee goes in depth to Clark winch operation and diagnosis. May be some one can help find it. In that thread oldseabee writes about the breather being a check valve not just a breather and if it is open both ways it can allow splash oil to seep out of the breather/ check valve.

kiko · June 12, 2017, 11:40:05 PM

That thread is titled Clark winch problems.

thecfarm · June 13, 2017, 06:13:23 AM

clark winch problems

treeslayer2003 · June 13, 2017, 08:50:35 AM

Quote from: kiko on June 12, 2017, 11:27:47 PM
Yes, but you can add the transmission fluid through the breather on the winch. I don't know how to direct to an old thread started by nblogger in which oldseabee goes in depth to Clark winch operation and diagnosis. May be some one can help find it. In that thread oldseabee writes about the breather being a check valve not just a breather and if it is open both ways it can allow splash oil to seep out of the breather/ check valve.

so it is the same breather/check valve as on the converter then.....
but why would you have to add fluid to the winch?
i am afraid seabee may have left us. that man forgot more about clarks than i will ever know.

coxy · June 13, 2017, 11:56:47 AM

if anyone is looking for a spare clark/Lufkin winch I have one that ill let go only to a FF member

kiko · June 13, 2017, 05:15:00 PM

Treeslayer, like you stated if the transmission is full the winch is full. same circuit. It is just easier to fill the transmission at the winch than in the cab holding the floor board up and the bucket sideways. Either way the same thing is accomplished.

Clark668C · June 15, 2017, 09:31:44 AM

Thank you all for the advice as I scroll through the comments I learn something new about my machine. I've been a coastal faller here in British Columbia for 30 years and was in a bad falling accident in 2014 leaving me with a crippled led and paralyzed left foot.My ex boss gave me the skidder and I've been trying to get this old girl running smooth with some difficulty its getting there and the info you guys share is very helpful,thanks again!
I've been searching for parts and haven't had much luck finding a good source. Does anyone know a good place to get a clutch pack and various other parts for my tranny system as well as the brake system on these 668C's?

Thanks

treeslayer2003 · June 15, 2017, 03:09:08 PM

why do you think it needs a clutch pack?

kiko · June 15, 2017, 06:30:45 PM

That skidder has a 2800 clark transmission. All wear parts such as seals, clutch and reaction plates should be available from Aftermarket Parts Inc dealer. Bowers transmission also .

Clark668C · June 18, 2017, 10:05:52 AM

My winch controls get hot to the touch and i'm wondering if its time to change the hoses that supply the fluid to function the winch?

coxy · June 18, 2017, 12:43:11 PM

if I'm right it will get almost as hot as the fluid in the tranny I know that's the way cat is

Clark668C · June 19, 2017, 09:26:12 AM

With my winch slipping on real heavy(30 000+)pulls i'm wondering if its got something to do with a clogged up line or the suction screen in the tranny?Living in a real isolated community has its challenges with finding a good mechanic let alone one that knows these Clark skidders. It seems that since my winch started slipping the control valve in the cab has progressively gotten warmer to touch as I use it more, some pulls it lifts the front wheels off the ground very easy without slipping and then the next pull it slips real easy.Frustrating when you just want to get that log to the road

treeslayer2003 · June 19, 2017, 04:53:22 PM

if your pulling front wheels off ground that is all it can do. however, the brake should never slip. i thought you meant the clutches slipped winching in. if the clutches slip this will create heat in the system. i suggest you get a gauge and test in various areas to see if lines are clogged/collapsed.

Clark668C · June 19, 2017, 05:34:38 PM

thanks treeslayer, i'll get a gauge and test the system this week and hopefully have some better news to report

MCLOGGING · June 21, 2017, 07:26:55 PM

If your still having problems with the winch ive worked on many clarks here in maine and on a slipping winch pulling in I always check pressures on the right side of winch where the adjustable free spool knob is located usually under that there is a 1/4npt plug test port on the pressure line that comes from the trans control valve. Should be 240-280psi if pressure is good and fluid is clean (dexron auto tranny fluid) than input clutch pack needs overhaul. Parts are readily available on minnpar.com I can give you part numbers for clutch disks and all seals if it comes down to that. Good luck!