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Need advice for tracking down 318 hydraulic fluid leak

4K views 14 replies 10 participants last post by  greenmotorman101 
#1 ·
I've got 318 with a 54" 4-way blade that I use alongside my 214 with a snowblower for moving snow all winter. At the very end of last winter, I had finished moving a bunch of snow and was putting the tractor away when I noticed hydraulic fluid all over the right side foot area, across the top of the pan in front of the seat and on the mesh on the right side and in the center below the steering wheel. (I initially thought it was just wet from melted snow.) I couldn't see where it was coming from, and everything still worked fine (drove fine, blade moved, etc.). I parked it right away, after which I could see the belly screen was also covered in fluid. The left side was fine - no fluid there. Not wanting to mess with it then, I put cardboard underneath it, walked away and figured I'd tackle it in the spring.

Long story short, I'm only now finally getting around to looking at it and can't find anything that looks like an obvious culprit. I've removed the pan, gas tank and belly screen and everything looks just "normal" dirty/greasy for a tractor with ~1600 hours on it. The fluid is a little low but not excessively so. The thing that really has me stumped is that there doesn't seem to be much going on on the right side in the way of hydraulics.

Has anyone seen something like this before and/or have any advice on what might have been leaking fluid badly enough, and that high up, to come out the mesh on the center/right side of the pedestal? I really don't want to have to tear it down any further than I absolutely have to as, like all of us, I have plenty of other things I also need to get done before winter. I'm happy to post pics if it would help.

Thanks in advance for any advice.
 
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#2 ·
Brent, Could be a hose or fitting on rockshaft cylinder or control valve. A cracked/split tube can spray fluid a few feet! Put gas tank back on and start tractor. check for leaks. Pull one hyd control lever and check for leaks, then other control lever. I'm thinking you'll see something! Bob
 
#4 ·
Bret, I had a similar leak on the right side of the fender pan on my 332, it turned out to be a leaky relief valve right on top on the right side. It only showed a leak when I operated the implements (snow blade), it should be simple to verify, only need to remove fender pan. Hopefully that's it, good luck!

Henry.
 
#6 ·
Followed Bob's advice and reinstalled the gas tank. Ran the tractor for a few minutes and operated the hydraulics (both levers and steering, but not the transmission - had the tractor up on ramps) repeatedly with no leaks whatsoever. I'm going to change the oil tomorrow as long as I've got it up in the air and I suppose then I'll drive it around for awhile and see what happens. Appreciate all the advice and will check the other suggestions if I can replicate the problem. Not often I want something to be wrong, but I'd like to find this before I'm dependent on the tractor.
 
#7 ·
If you have a heated area, you might want to wash down, hopefully with it clean/dry then you can get a better inspection. Plus less chance of dirt getting in the way when changing the filter and putting the hydro oil back in. Also put rear axle/wheels on jack stands. Just a time saver, you can refill the unit faster if you remove the plug where the hose attaches on top. Then check sight glass tube. Then run engine and operate the drive, turn steering, operate the rear hydro lift. Top off unit.
 
#8 ·
Brent, When you "tested", where you at WOT or just above idle...more rpm=more flow & pressure...? Did you go into "float" or just down pressure...or both!...? Did you hear a change in engine rpm/sound or relief valve "relieving"?
Just a WAG here. but try steering left full lock AND hyd, levers, then right full lock AND hyd levers. Bob
 
#10 ·
At/near WOT with full range on both the steering and levers. Didn't notice any change in sound. At the same time, I have zero experience with hydraulics so not sure exactly what I should have been looking/listening for.


My bet is steering valve filling up the steering column, takes a long extended use session to fill it up then leak out and drop down. May not notice when used briefly.

I’ve had to rebuild several of these with similar symptoms.
Any tips or info on what I'll need if this is the case? I'll do my own research in the meantime, but anything you can share is much appreciated. I'm confident in doing the work once I figure out what needs doing.
 
#9 ·
My bet is steering valve filling up the steering column, takes a long extended use session to fill it up then leak out and drop down. May not notice when used briefly.

I’ve had to rebuild several of these with similar symptoms.

Good luck.


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#12 ·
Brent, I've always had my fender pan on my tractors so I can/t explain what to listen for as far as relief valve, but you should here a change in your engine. Maybe try half throttle. Your outer lever may take a few seconds as this is moving your rockshaft cylinder, but when cylinder is at the end of its stroke engine should start to labor...just a little.

While cylinder is moving, there's very little power required as it needs only a few psi hyd. pressure. Once it gets to the end of its stroke the engine has to turn the pump to produce 900 +/- psi. This typically slows the engine a little and the sound deepens...governor kicks in and supplies more fuel to maintain rpm.

Never messed with power steering, but I search here may revile a thread or 2. Bob
 
#13 ·
You’ll need a rebuild kit from Deere and the shop manual. It’s not terribly hard, but takes some time to remove the valve.

Kit PN is AM107078

It’s not cheap (~$100) but it has everything you need.

Be very careful during disassembly and assembly of the valve, highly recommend making a fixture to hold it like shown in the manual.

Keep any eye on all the layers and take lots of pictures along the way.

-Andy


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#14 ·
JD Hydro Fluid dye may help you find the leak
Part Details
Part Number: MT3668
Part Price: 3.91 USD
Description: FLUID, HYDRAULIC OIL DYE

Deere uses a red dye in the hydraulic oil to help identify oil leaks on the assembly line.
Deere has adopted a part number for the red dye, MT3668. This is available in a 12 mil. bottle which will treat 5 gallons of hydraulic oil. Readily available from your local dealer. Reference DTAC solution 67928.
 
#15 · (Edited)
Also sounds to me like the typical steering valve leak. But I’m surprised you didn’t have fluid coming out up underneath the center of the steering wheel. Pretty time consuming repair process to remove and replace the valve but once it’s on your bench the actual rebuild process is not too bad. Number all the hydraulic lines when taking it apart. It’s pretty hard to put it back together wrong but it can happen. Take pictures from all angles before you start wrenching. BTW. It involves laying on the ground and working looking up so a good wash job before you start can make the job much more pleasant.

Be extremely careful to avoid putting your fingers or other skin where it can be penetrated by high pressure fluid leaks. Amputation is common treatment when this happens. Use a piece of cardboard or clean and dust with talcum powder to find leaks.

Red fluid dye is a very good tool.

Max.
 
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