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GLwelder
02-24-2009, 07:08 PM
I bought an older skid loader last year and it works great except that I've gone through about 15 gals of Hyd-fluid over the past 6 months. I just spent the past week "rebuilding" the control valve and replaced all o-rings on the lines that go in and out of it. (You have to be double jointed to work on this thing). I was certain that this is where the main leak was. Anyway got it back together this morning and of course the dam thing still leaks, maybe not quite as bad.

My main question I guess is there a colored additive I could use to make the source of the leak more apparent?

Thanks for any feedback.

DSW
02-24-2009, 07:20 PM
If you can borrow or rent a hot water pressure washer or better yet find a location with a steam cleaner, clean the pi$$ out of it. A little simple green sprayed on it and allowed to soak works well once you have the oil soaked dirt removed. I've worked on dozens of machines with "mystery" leaks, and until its clean you'll rip out your hair trying to find it. with it clean you can start to narrow down the problem area.

We used to have a CAT 988 rubber tire loader that we referred to as the "EXXON Valdese". Leaked 5-10 gal of hyd fluid a day. Used to keep a 55gal drum of oil on the catwalk with a hand crank pump to top it off daily. We knew where the leaks were, but to reach the fittings to disconnect and change the hoses required splitting a 40ton machine. Needless to say it leaked till the day we sold it.

Oldiron2
02-24-2009, 07:44 PM
I think there are standard dyes, and know there are fluorescent dyes that are used in both lubricating oils and in refrigeration systems. You need a black light to get the fluorescent type to glow but they show up better, and I think the kind of light which makes posters glow will work too. This examination needs to be done in the dark, of course.
BTW, I had some engine oil which glowed without any dyes being added; no idea what brand or type, but if you have a blacklight handy, you might try it before you buy any additive. Not likely that hydraulic fluid would glow, but who knows?
Another cheap trick is to clean it well as suggested above, and then spray or dust the areas with flour which will adsorb any leaking oil and quickly turn color, making the leaks show up better.

denrep
02-24-2009, 09:37 PM
Hello Glwelder,

Also...
Study the possible leak points in an oily area, and try to isolate the circuit(s) that may be leaking.

With a warm system, stall the suspected circuit(s) against the relief valve. With the system pressure raised to relief, a pressure leak will usually be more obvious and easier to trace.

Good Luck

David R
02-24-2009, 09:58 PM
CLEAN it first. Use gunk and a garden hose. Get it clean and let it dry. Run the machine for a few minutes only. Look for leaks.

David :)

farmersamm
02-24-2009, 10:34 PM
I'm sure everybody knows it, but just to refresh memories.

If it's a high pressure pinhole stream that's coming out. Do not put your finger in front of the stream up close. You can get one hell of an infection if the high pressure stream punctures the skin. It's like those hydraulic vaccination things that they use instead of needles.

Use a piece of paper if it's a leak stream under pressure.

maniacmechanic
02-25-2009, 12:24 AM
i agree with farmersamm on that one i know a guy from the tech school i go to was adjusting the tracks on a d8 dozer and when he opened the bleeder it malfunctioned and shot high pressure grease into his hand i know grease and oil are a bit diffrent but thats how we learned to check pressure leaks in hydraulic systems he had to have some kind of surgery to remove the contamination i would do like everyone else said and clean the s*** out of it and then operate for a few minutes then check and flouresent dyes are very helpful

Magnetic Mechanic
02-25-2009, 02:10 AM
I used to run the maintenance dept of a transit authority and some of our buses had air starters. One bus had a small air leak and would be out of air every am, and of course needed to be jump started. No one was able to find this leak, and day after day it played hell at am pullout.

Onn day Tommy Polland came to me and said, "Let me put that bus on the pit and I'll find the leak in ten minutes"

Well, go for it, says I.

Tommy dumps the air,squirts in a shot of R22,
Pressures up the tanks and grabs a freon leak detector.

Didn't take long to find that leak.

May not be applicable here, but someone , some day, may benifit from Tommy's idea.

And be sure if you do, to us R34A.

Oldiron2
02-25-2009, 03:56 AM
And be sure if you do, to us R34A.
I think you missed a key; it's R134A.

Great idea. If you don't have a commercial detector, a propane torch jury-rigged with a tube to feed the air to the flame can be used. When the freon burns, the acids produced react with the copper to give color to the flame.

maniacmechanic
02-25-2009, 07:25 AM
well damn thats a good idead i would have never thought to use refrigerant that way gotta give him pat on the back for that one ill talk to my instructors bout it today and see what they have heard bout that

steve45
02-25-2009, 09:11 AM
You can clean the area well and spray it with the white developing powder that is used in the Dye-Chek crack detection kits.

aggmechanic
02-25-2009, 10:54 PM
:rolleyes:what ive found to work best for me is brake clean. if you have oil seepage high or low preesure and dont have time to pressure wash just find or figgure out were you think the leak is and spray it down good with brake clean take some compresed air and blow it off. brake clean is a good and fast drying solvent and will evaperate quickly exspesialy if you blow it off with air. it will leave the suface oil free. if you see oil resadue after you have "spot cleand" the area you know for sure were the leaks are.

i work on mainly agg. equipment and dont have a lot of time or the facilatys to wash a machine before i work on it.(ecspesialy when famer dan is trying to get his crop out the feild and is in a big hurry!!!) so brake cleaner and compresed air are my best frends! also the cheeper the better! but be carefull some brands will take the paint right off of what ever they land on and sit!!!!!

as far as getting "tattoed" it is painfull an can kill you!!!!!!!!

compresed air, compresed gases, pretty much any thing that is conciled under pressure can be injected into your skin. so be caefull i have been tattood a couple of times myself and was very luckey both times my own stupidity you can never be too carefull!!!!!



im a mechanic not an english major:rolleyes:

GLwelder
02-26-2009, 05:07 PM
Hey guys thanks for the feedback. As far as getting a hydro-fluid injection, its something I had heard of. A friend of a friend actually died of a massive infection from such a thing.
I tried to use multi-quote to reply individually, but haven't figured it out yet (I know a couple of you are thinking thats a good indication of why I can't find a simple leak).

I cleaned up the entire area of the pumps, drives and valves. I noticed a leak on a pump input and will change that o-ring next. It sure didn't seem like enough to cause a puddle, I'll change it and go from there.
Denrep, I like yoiur idea of maxing a movemrent out and looking for a leak. I have to remove the seat and sit in there backwards which makes it a challenge. I didn't notice any major high pressure leaks, just a couple of wet spots. I give some feedback after I install that o-ring.

specter
02-27-2009, 12:01 AM
I have used the dye and black light and it works fine. But so does the flour on the suspect area.
Just be careful not to put your hands or face in that area of the suspect leak. When the item is put under pressure that leak could all of a sudden shoot that fluid at you at over 3,000 psi and slice thru skin like a razor.

aggmechanic
02-27-2009, 12:38 AM
gl welder what type of machine is this your working on? a skid steer? if it is i can probably be of some help those machines will get you hurt quick if trying to work on thim improperly. if you need to run the machine to check things out make suer you lock out the boom in the raised position and also be sure to get all four tiers off the ground so the machine wont take off on you while your messin around in there.

also check around the hydrostat pumps trunion seals are bad about going out in these machines no matter the brand. not saying thats your problem but that is something that commanly happens.

feel free to ask for help. its better than breakin something or getting hurt

J Hall
02-27-2009, 12:54 PM
Stating the make and model of machine could get you some good ideas of common problems.

GLwelder
02-27-2009, 11:42 PM
gl welder what type of machine is this your working on? a skid steer? if it is i can probably be of some help those machines will get you hurt quick if trying to work on thim improperly. if you need to run the machine to check things out make suer you lock out the boom in the raised position and also be sure to get all four tiers off the ground so the machine wont take off on you while your messin around in there.

also check around the hydrostat pumps trunion seals are bad about going out in these machines no matter the brand. not saying thats your problem but that is something that commanly happens.

feel free to ask for help. its better than breakin something or getting hurt

I know what you mean by getting hurt, it is difficult to look in at the plumbing while actually moving things.
I'm not sure what the trunion seals are, I'll look them up in my parts book. I will definetly take you up on your offer of help, I am an average mechanic with no experience on skid steers. I have to work this weekend so I won't get back to finding this leak until next week.
Thanks,
George

GLwelder
02-28-2009, 12:04 AM
Stating the make and model of machine could get you some good ideas of common problems.


I bought a NH L455 last fall. I believe it is a 1987, with 2000 hours, 200 hours on a rebuild of the 28 hp Kabota diesel.

aggmechanic
02-28-2009, 02:28 AM
on a skid steer you have hydrastat pumps(piston) and an hydralic pump (gear). the hydostat pumps are mounted on the back of the moter (flyweel side) there will be two of them monted together or be a one pice unit with two sprate pumps in them. in other words the engin drives the first one and the first one is bolted inline with the second one so it drives the second one. your hydralic pump is either mounted inline with your hydrostats but on most machines it is driven with the front of the engin(via a coupler off of the crank/front pully) the hydrostats and moters(before i get too far ahead of my sellf there are two moters. those make the machine move. you have one "hydrostat" pump for each moter. one is your left and one is your right) are a closed circut. now i could go way into depth on how the pumps work but for now to keep it simple the trunions are what the rotating group pivots on so the pump can go from no displacment to maximum displacment either way (forward or reverse). those trunions are mounted in the pump on both sides they look like a cap. might have three to four bolts in them. there are seals in the cap. !!!but!!!! there is a trick to puting those seals in those caps are shimed you have to pay attention to that also when you go to put thim back in they are easy to cut so you have to be carefull.


now that ive said all that that dosent mean thats were your leak is . but i have worked on a lot of machines and this is a commen problem. BUT DONT GO AND GET ALL GUNG-HO make sure were your leaks are fix thim one at a time. k-i-s-s that the best thing to do.

now about how to work on that machine and not be in the seat? thats easy get some good cribing 4by4 8by8 somthing like that no!!!! cinder blocks!!! jack the machine up and put the cribing up under tha machine so as to get all four tiers off of the ground. raise your boom and lock it. if the machine dosint have a boom lock make one out of angle iron or put somthing under the bucket so in the event some thing fails or you take the worng line loose it dosent squash you(use good jugement). remove your seat and floor unlesss that model will let you raise or slide the operaters plate form out the way then you can run the machin and check all you want to and not have it run over you.

good luck
ryan

GLwelder
04-24-2009, 10:27 PM
Finally got back to working on my leaky SL. I took the covers off again and tore into it; I replaced every o-ring I could find and tightend every nut. Spent 4-5 hours. I refilled the hydrolic reserve and ran the machine hard; No leaks on the driveway!

I have since used it a few time w/o any significant leaks noticed (there's a tiny half dollar sized spot when parked for for a few hours, I can deal with that).

Now I can use the thing w/o adding 2 gals of fluid each day.

Thanks for all the feedback!

specter
04-25-2009, 10:16 PM
Glad to hear that you got it fixed. That little bit of leaking mmay stop on its own once the rings sit in place.

GLwelder
04-26-2009, 10:59 PM
Glad to hear that you got it fixed. That little bit of leaking mmay stop on its own once the rings sit in place.

Your correct, the leak must have been left over fluid in the pan or a connection sealed up.

I was very pleased to use this thing and not have a gallon of hydro-fluid on the drive to cleanup. I was almost ready to surrender and trailer it to the dealer. The only thing that stopped me is my pride and that fact that I'm pretty cheap!

temponly
05-01-2009, 12:56 AM
Just an after thought.

I had the same issue with a JD125 Skidsteer.

My Hydro shop said they use a UV dye designed for both oil or Hydraulic systems. They told me that some John Deere equipment ship with UV dyed Hydro Fluid from the factory and that John Deere can order 5 gallon UV dyed fluid from the factory $$$$.

Instead, they sent me to my local NAPA dealer. NAPA has UV dye fluid in small 6oz bottles which treats about 20 gallons. Its designed to clean easily with degreaser/soap and glows purple under a UV light.

My leak was in a fitting which I never would have found otherwise. A bonus is, that until I completely change out my Hydro, the dye continues to work.

I hope this was helpful.

b.rey

jbar
08-02-2015, 08:51 PM
aggmechanic,
I have a Gehl 4625 with a leaking trunnion seal just as you described in your post back in 2/26/2009. It's a Eaton 70344 double piston pump. I replaced the trunnion seal while the pump was still in the skidsteer...and it didn't fix the leak. Having read that some trunnions have o-rings inside the pump housing I removed the pump and took the front pump only (it's a tandem pump) apart. No o-rings! Looking it over I can't figure why it leaked with the new seal, however it did. The shaft has slight visual wear, but I'm a hobby machinist and could detect no measurable difference in diameter within a couple 10 thousand's. However you can feel a very slight wear on the shaft. Questions: What have you done in the past to repair leaks around trunnion shaft - any tips/etc?? Also, would anyone recommend turning the shaft down on a lathe in that area, braze the shaft back up and then turn it down to exact dimension? I've heard of that being done for shaft repair before. Any special type of rod to use?
John

DSW
08-02-2015, 11:26 PM
Note that aggmechanic hasn't been on this site since March of 2010, so I wouldn't hold your breath waiting for him to reply. There are a number of others on here with hydraulic experience though. Maybe one of them can help you out. It might work best if you started a new thread and put in all the details, and maybe one of them will chime in and give you a hand.

Good luck.

Willie B
08-03-2015, 08:02 AM
As you say these things are impossible to get your head to where you can see a leak. A good inspection scope is a valuable tool. It takes a while to get to where your brain processes what you see on the screen. There is no perspective. It's hard to figure out what you are seeing.

whtbaron
08-04-2015, 10:06 AM
Not the problem with these machines, but we were using a JD skidsteer to move snow. When the cold snow hit the aluminum housing of the hot hydraulic pump, it split. Just a little word of warning if you would like to prevent a much much larger leak...