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Author Topic: 518c skidder torque converter help  (Read 804 times)

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Offline twinstaxx

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518c skidder torque converter help
« on: October 11, 2017, 09:30:34 am »
My buddy has a 518 C cat skidder. he had the transmission and torque converter rebuilt and everything in both of them was put in new except for 3rd gear clutches. Now when you get it in a hard pull it will pull the engine down until it quits pulling. It acts like to me the stall speed in the torque converter is too low. Is there any kind of blockage or anything you could change that would change the stall speed of the converter or make it act like it's too tight. He's running 30 weight oil in it. it was rebuilt somewhere between six months and a year ago. It's his only skidder and he just been getting by with it so he ain't out of commission again. he had the pump rebuilt when the transmission was rebuilt. they tried to put a bunch of fuel to it and a bigger Turbo and and all that done what's costing more money in fuel and didn't really improve the situation any. also all parts came from cat no aftermarket anything

Offline kiko

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Re: 518c skidder torque converter help
« Reply #1 on: October 11, 2017, 12:48:51 pm »
When the engine pulls down does it blow black smoke?   

Offline twinstaxx

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Re: 518c skidder torque converter help
« Reply #2 on: October 11, 2017, 11:57:07 pm »
Not the turbo he had I bigger turbo in making 30lbs of boost not much better.  I think I might be on to something. He said you can run it all day and pull the dip stick out of the trans wipe it with your fingers and the oil is just worm.  I am  wondering if the oil not being hot it isn't thin enough to give you the desired stall speed. But the nest questions is why wouldn't it be at least as hot as the coolant temp.

Offline twinstaxx

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Re: 518c skidder torque converter help
« Reply #3 on: October 12, 2017, 05:43:20 am »
Dose anyone have a PDF of the shop manual and or trans oil schematic

Offline coxy

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Re: 518c skidder torque converter help
« Reply #4 on: October 12, 2017, 06:20:30 am »
the oil in my tranny does not get as hot as the motor oil if my motor temp is half in the green the tranny temp maybe 1/4 or less in the green our  518 takes  15/40 same as the motor

Offline coxy

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Re: 518c skidder torque converter help
« Reply #5 on: October 12, 2017, 06:27:13 am »
the older 518 took 20wt in the winter 30wt in the summer but all the newer ones run 15/40 motor oil not shur what year it started but my 81 says use 20-30wt drive train oil  the 89 says 15/40 motor oil that what the book says

Offline kiko

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Re: 518c skidder torque converter help
« Reply #6 on: October 12, 2017, 11:12:04 am »
If the load is behind the engine it will black smoke when the engine is stalled.   If it pulls down with no smoke it is an engine horsepower issue.  I was not inquiring about the turbo. 

Offline twinstaxx

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Re: 518c skidder torque converter help
« Reply #7 on: October 12, 2017, 10:25:23 pm »
If you pull it down with a load it says clear at first why the turbo is lit. Then it will get under the turbo and smoke . Since it started happening they have rebuilt the pump, turn the pump up, put a bigger turbo on it (that would build 30 lbs of boost) and did a compression check which was good. 
I pushed up against a tree got the trans temp to about 270. Pulled the dip stick and the oil on the stick was about 120. It was in use for about 2 hours prior to that
When i first looked at it I thought engine to but every time I think of something they have checked it.

Offline kiko

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Re: 518c skidder torque converter help
« Reply #8 on: October 13, 2017, 12:19:01 am »
Seems like a lot of money and time has been put into this issue.  So just an idea.  When the pump was removed and replaced was the engine rolled in direction of rotation in order take gear lash out of gear train. 

Offline mike_belben

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Re: 518c skidder torque converter help
« Reply #9 on: October 13, 2017, 01:36:27 am »
Is this a mechanical injector pump?


Im inclined to think the tightened up trans is revealing a low power situation for the first time.  Does it use a lift pump to feed the high pressure pump?

Offline mike_belben

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Re: 518c skidder torque converter help
« Reply #10 on: October 13, 2017, 01:40:02 am »
My komatsu dozer has a hidden screen filter in one of the fittings before the injection pump, its in an eye bolt.  Id never seen such a thing prior but sure enough when clogged she dont pull on top at all.   Look hard at the fuel plumbing for delaminated hoses (real common on formed rubber elbows) and places where screens and check balls may live.

Offline coxy

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Re: 518c skidder torque converter help
« Reply #11 on: October 13, 2017, 05:59:58 am »
there is a lift pump for the injector pump it should be on the frame on the starter side  below the engine side screen  there is a screen filter there  and was told there is a small screen in the pump its self never had any trouble with mine   270 for temp on the tranny sounds high like I said nether one of my 518 hardly get in the green even after pulling up hill    I would make shur they don't have it a tooth out of time does it sound like its laboring when its at an idle  our 89 is pumped up and skid mostly in 2nd gear is all it wants to do is dig holes in 1st    has this been trouble from day one after the tranny rebuild or just start  one of the tranny lines isn't hooked up backwards is it 

Offline twinstaxx

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Re: 518c skidder torque converter help
« Reply #12 on: October 13, 2017, 04:14:25 pm »
Is this a mechanical injector pump?


Im inclined to think the tightened up trans is revealing a low power situation for the first time.  Does it use a lift pump to feed the high pressure pump?

Yes. They said they checked the pressure on it and it is good. Does anyone know what it is supposed to be

It would spin the tires in 2nd when it first was done . Then it has slowly gone down hill. I pushed up against a tree and held on the throttle to heat it up to 270 it always runs low on the gauge in normal use. If someone has one of these can you pull the dip stick after a couple hours of use and tell me how hot the oil on the stick is. This one was only about 80 or 90*.

Offline twinstaxx

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Re: 518c skidder torque converter help
« Reply #13 on: October 13, 2017, 04:24:40 pm »
Also thanks for all of your help

Offline Neilo

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Re: 518c skidder torque converter help
« Reply #14 on: October 13, 2017, 05:01:07 pm »
I have been around here for a little while. My advice is, listen carefully to Kiko and give him the information he is asking for to help you.
Good luck with it.

Offline coxy

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Re: 518c skidder torque converter help
« Reply #15 on: October 13, 2017, 07:53:38 pm »
Is this a mechanical injector pump?


Im inclined to think the tightened up trans is revealing a low power situation for the first time.  Does it use a lift pump to feed the high pressure pump?

Yes. They said they checked the pressure on it and it is good. Does anyone know what it is supposed to be

It would spin the tires in 2nd when it first was done . Then it has slowly gone down hill. I pushed up against a tree and held on the throttle to heat it up to 270 it always runs low on the gauge in normal use. If someone has one of these can you pull the dip stick after a couple hours of use and tell me how hot the oil on the stick is. This one was only about 80 or 90*.
that's about right after 5-6hours use the oil is warm to the touch not like motor oil that will burn ya 

Offline twinstaxx

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Re: 518c skidder torque converter help
« Reply #16 on: October 13, 2017, 10:32:22 pm »
Idk if they took the lash out of the gears when they did the pump. I didn't have anything to do with anything that was done  to this point. I had never seen it until last week. Trans was rebuilt above t a year ago m the other stuff followed. I am wondering it the timing could have slipped after the trans was done and when the pulled the pump they put it back to the same place it had slipped to.

Offline kiko

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Re: 518c skidder torque converter help
« Reply #17 on: October 13, 2017, 10:44:36 pm »
It is possible that the injection pump was the problem and might have fixed his issue if it was timed properly.   Also the hand primer pumps are notorious for sucking air. 

Offline twinstaxx

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Re: 518c skidder torque converter help
« Reply #18 on: October 14, 2017, 08:53:48 am »
What area on the pump usually sucks air (fitting on suction side)?
 I haven't set the timing on this particular model of engine. Is there any special tricks. Could I add  a little timing while I am at it maybe to help a little?

Offline kiko

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Re: 518c skidder torque converter help
« Reply #19 on: October 14, 2017, 07:50:56 pm »
It has been at least 15 years since I worked on a 518,  with that being said, there is a plug in the flywheel housing near the starter that takes a 9/16 to remove.
 Rotate the engine in direction of normal rotation with a Phillips screwdriver until you find the timing hole in the flywheel.  Now adjust so a 3/8 bolt will thread in. The engine is now top center compression 1 or 4 If on 1 intake and exhaust valves for 1 will have lash and both valves on 4 will be tight.    There is a plate on the injection pump that has four small bolts, remove it and there is a slot in the pump cam that a 3/8 bolt will fall into when the pump is timed.   So rotating the engine in normal rotation, if the pins both fall at the same time it is timed correctly.   The pump I am speaking if is the hand primer pump not the lift pump, the pump itself does not have fittings on it, and is probably mounted on the filter head, but I can't recall if the 518 has one or not.   Also as Mike mentioned, check fuel supply fitting especially any 90 degree fittings. I would assume the main supply hose from tank has been blown out?