Daewoo 130 LCV - extremely weak tracking

[John Tobin]

Hi All
I am looking for some advice on a 1999 Daewoo 130 lc v that I have just bought - the issue with it is that when hot it basically loses tracking power.
It seems to have good digging power for example at the weekend it was good and hot at which point the tracking was absolutely horrendous so I tracked over to stump from a good size tree that I had cut down recently and went about pulling it up. The stump was fairly solid and the machine was either pulling itself over (i.e the whole back was lifting up off the ground) or the whole machine was being pulled in towards the stump. Would this indicate that digging power is ok?
On the tracking it tracks fine when cold in that she will spin herself around without the assistance of the boom/slew and will climb up a fairly steep slope and tracks in a reasonably straight line. Also the high speed tracking seems to also work fine when cold. Once it is hot it doesn't track straight at all and has zero power if I push one on the travel levers on the machine the track tries to turn but fails, the engine does not load up under these circumstances. When I push both levers together it will move the machine around just very slowly
I have got my plant mechanic on it and he is an experienced guy so I have moved the machine to his workshop - he says he wants to replace the seals in the swing center first to remove this as a potential issue as the seal kit is only €220 from Doosan. He will go from there with checking pumps and motors etc. On the track motors would you have any idea what sort of case drain flow rate would indicate the motors were bad/good. Also are there any other diagnostics I can perform on the track motors? I also want to change all the fluids is there a specific grade of hydraulic oil I should be using or one that has better stability when hot
Thanks for the help and advice

 

[Nige]

Good advice to replace the seals in the swivel as a first step. Get that done and see how you go from there.

 

[John Tobin]

Will keep you posted how it goes will be a week or so before my mechanic gets to it
Anyone have any ideas what a normal case drain flow would look like
Thanks again

 

[uffex]

Good day
Case drain equates to internal leakage you can see this on a pressure gauge how quickly the residual pressure drains away.
Kind regards
Uffex

 

[John Tobin]

Hi Uffex, thanks for the reply is there a rate of change in pressure that is acceptable for case drain -
Also do you know what the pressures at the track motor should look like for normal operation
Thanks John

 

[uffex]

Good day John
The crawler pressure according to spec is 324 ba. The case drain should not signifcatlnly increase when you use the crawling circuit. You can see this by "a" connecting a low pressure gauge into the case drain line and "b" a high pressure gauge to the crawler drive lines. If you would like specific information making it will take us a little time but happy to help.
Kind regards
Uffex

 

[John Tobin]

Hi All
Just a quick update on this Daewoo excavator, posted a couple of photos as well for good measure. The machine has 12k hours on it and I paid 13000 Euros (~$15,000 USD) including a hydraulic hitch and 3 buckets.
It is currently sitting with my mechanic who says he will probably get to the machine next week. He did however drive it and had the following observations
1. Cycle time for slewing boom etc seemed normal so he doesn't think the main pump is a problem - he also observed that the main pump was replaced at some time as the pump is a different color so it is either a replacement or rebuilt unit. This is inline with what the seller told me as he stated it was changed 1000 hrs ago (although i never put much weight on anything a private seller says)
2. He thinks that even when cold and moving the machine around that the tracking is very poor, he said there was no bite to the unit (his words). So while I thought it was fine when cold and terrible when hot he thought it was very poor even before the machine was hot. So I will have to retract my statement about the machine being fine when cold
3. He thinks tracks, chains and sprocket are very good, but that a link should be removed from each chain as they are very loose even though the idlers are fully extended
4. There is no slop between undercarriage and main body of the machine so the slew gear is in good condition
We are going ahead with pulling the swing center/rotary valve and resealing. Thus my only problem is the tracking - the track motors are hy-dash units (gm18 i think) - and while the info from Uffex above is very useful my mechanic is still looking for a case drain flow rate on these units in litres per minute (or gpm).
From my side i am interested in understanding how i can tell if the motors are bad themselves and what it might cost to either a) rebuild them or b) put in a new or remanufactured unit
Also I purchased the shop manual online printed and gave it to the mechanic - so if anyone wants it i can share
Thanks for any help John

 

[uffex]

Good day John
A copy of the applicable manual would be useful we can then put some information together for you to diagnose where the trouble is coming from.
This may take us a little while but happy to help.
Kind regards
Uffex

 

[Nige]

Good update John, but I would take issue with his comment "the tracks, chains and sprocket are very good", because if "a link should be removed from each chain as they are very loose even though the idlers are fully extended" then the pin/bush joints are probably very close or even past being 100% worn.

 

[John Tobin]

Hi Nige - would you visually see that sort of wear or is the looseness of the chains the only indicator? The chains themselves and the sprockets don't seem that worn when you look at where the sprocket and chains are meshing. I would take a picture but the machine is with the mechanic
Thanks John

 

[Nige]

If the tensioner is all the way out the chains are at the end of their life IMO. I'm not saying that you can't remove a link to get the tensioner back and carry on using them. It seemed strange to me the mechanic's comment that the U/C was very good when the tensioner was all the way out and the chains still weren't tight.

I don't have any undercarraige specs on these machines so I have no idea if they are imperial or metric measurements. It would be interesting if the track chain pitch spec could be found to measure it now just to see how much it's extended from the original spec.

If you want to see how worn the tracks are and you fancy splitting one of them, knock the master pin out and lay the track out flat, shoes down. Then see how far you can push one end sideways before the other end starts moving, I reckon it will probably go a metre or so sideways.

 

[John Tobin]

Hi Nige - I will see what he says next week when I call in to him to check on progress
The key thing for me is to keep the cost as low as possible as I only want this machine to do 500 hours work for me sorting out farmland over the next 2-3 years - the machine will be used for personal use only. Definitely don't want to put new chains on the machine so if I can get away with taking a link out I think I would chance it.
Or if I get the tracking sorted I might continue as is.

 

[funwithfuel]

Don't forget to check the front idler axle. If that is failed , you'll have a very slack chain as well. The condition of the undercarriage speaks to the concerns of the travel function. If the chains were run tight or in sandy material without maintaining slack, the motors may have been overworked. Is the problem in both directions? Forward and reverse ? Since your mechanic performed cycle time tests , how did left and right high and low shake out vs specs? Has anyone gauged pressure to left and right? Has anyone swapped reliefs left to right, forward to reverse?
Case drain , as a rule should not exceed 10% of flow delivered to motor at full load. So if you have 30 gpm at full stroke, your case drain may not exceed 3 gpm. To be honest, if I saw 10% I would condemn the motor. It's a ridiculous amount. Additionally, case drain should mildly leak out , it should not stream, spurt or spray. Does your machine have a case drain filter. I would look there first. Its almost always neglected. Spin on a new one and cut the head off the old. Look for debris.

 

[Nige]

The key thing for me is to keep the cost as low as possible as I only want this machine to do 500 hours work for me sorting out farmland over the next 2-3 years - the machine will be used for personal use only.

In that case taking out a link would be fine, especially if you're the one using it. You're likely to treat it with much more care than an hourly-paid operator would.

 

[John Tobin]

Thanks Nige for the reply I am afraid for the next few weeks I am going to have to take a wait and see approach
@ funwithfuel thanks for the in-depth response
1. I will be sure to check the idlers
2. Travel issue is in both directions and both motors are equally weak
3. Unfortunately I am not sure what you mean by high and low shake out Vs spec . My mechanic basically gave it the machine a quick run and the observations he made were as above - hopefully will get more info as he properly gets into the machine
4. No guages have been on it yet or swapping of reliefs my guy is going to eliminate swing center first as an issue then assess track motors
5 case drain goes through main low pressure return filter - I have full filter set bought for the machine so all will be replaced.
Thanks for the case drain info - I have a feeling I might be dealing with 2 worn out motors and I am not sure if they will be worth replacing based on the value of the machine. I might have made a bad call on this purchase
Will update this thread as the situation evolves
Thanks to all for the great info and help

 

[funwithfuel]

High and low vs spec. This means paint a track pad put machine in turtle or slow, use the boom to raise that track off the ground. From a running start,at full throttle, time 3 full revolutions. Do the same thing in rabbit or high. Then do the other side. Your service manual should tell you what your time should be. This will give you an indication of flow versus pressure. If your unloaded speed is correct, you may have a weak relief(s). I would like to see gauged pressure before condemning travel motors. I know I'm throwing a bunch out there, I would just rather folks cover all aspects before spending huge chunks of money to still have the same problem.

 

[John Tobin]

Hi funwithfuel have that info from the manual and I will perform that test once I get my hands on the machine - I definitely won't be spending any big bucks on this machine without making sure the right problem is being addressed
Specifications for Solar 130LC-V
Travel Motor Jack-up Test
3 revolutions
High Speed seconds 17.9 ±0.8
Low Speed seconds 26.3 ±0.8

 

[Dave Neubert]

I agree with Nige if the idlers are all the way out and tracks are loose they are wore out excavators will wear out the tracks internally can't judge by rail height. also I would look at the hyd swivel

 

[Bluox]

With that many hours on your machine a swivel reseal is a good first step. As far as your tracks go you can remove one link and run them without any problems. I have had customers remove two links and run their tracks thru the bushings on the pins then replace the whole undercarriage .
Good luck
Bob

 

[uffex]

Good day John
Response to your tracking issue.
Kind regards
Uffex