It's the area right next to the big oily mess.

Identifying the source of a hydraulic leak can present some unique risks of injury to the person attempting to find the defective part. So before I say anything else let me say that you NEVER try to locate a hydraulic leak by feeling for it with your hand (nor any other body parts). Also if there is a need to push, pull or otherwise move a hose during operation when searching for a leak, use only a wooden dowel or stick to contact the hose. Eye protection is also recommended because the oil may squirt a good distance if the leaky spot is suddenly exposed when moving the hose.

Now then we go to the problem of finding a leak.
The first thing to do is to power wash the area completely to remove oil and dirt/debris build up cause that stuff is going to hide the leaky point.
If this is a significant leak, you should be able to actually see the defective hose or fitting the oil is escaping from.......provided of course that you can even see into the area where the leak appears to be.
For areas that are at an "off angle" I suggest trying a mechanic's mirror.

If the oil leak is not so significant as to form an actual stream or drip, another method can be used to make the leak show up.
Clean the components you suspect of leaking and let them dry thoroughly. When the surfaces are dry, spray the surfaces with a talcum powder based aerosol deodorant. The talcum powder will leave a highly visible white film and when oil contacts the powder it will darken and there is your leak.

If the leak is coming from a hydraulic cylinder you can check by simply wiping the rod end where it emerges from the cylinder with a clean paper towel after operating the cylinder a few cycles.
Welded cylinders can crack at the weld and leak. Tie-bolt cylinders may leak at the O-ring that seals the end plates to the cylinder.
Leaks suspected to be on a hydraulic pump are best checked with the talcum powder trick.
Leaks suspected on hydraulic control valves can be checked in that fashion too.
Once again I say do not use hands to feel for a hydraulic leak. High pressure oil escaping from a hydraulic system WILL penetrate skin and body tissue causing a horrific injury and hydraulic oil is highly toxic in itself if ingested or injected into the body.

So.........what the heck are you working on? :^)

Thanks mownie, I had a feeling you'd be knowledgable on this.

First, I was fortunate enough to take the time to do a little research before looking for the leak and found out about the dangers involved. For some reason it just never crossed my mind how extremely dangerous hydrolics can be and I would have been feeling around with my hands. I appreciate your re-emphasizing safety.

Secondly, the only advice I could find for locating a leak was to add a die, but I didn't want to end up staining the concrete. Your suggestion of talcum powder based aerosol deodorant is an excellent alternative. Thanks big time.

If you are interested in the details:

The tractor is a 1996 Steiner 420 that I bought primarily for plowing the drive but also use for mowing as my wife wouldn't let me keep the Craftsman YT 4000 and the 420. If you are familiar with them, you know that Steiner pacts an awful lot into a very small space.

This Spring, I began noticing that the 420 was driping hydro fluid during mowing. Not a steam, but slow steady dripping from the drain plug and the bottommost hose of the five hoses that run from the rear transaxle nad hydro motor at a point just in front of where they all go through the frame channel under the tractor foot platform.

The problem is, I can't get it to do it on demand. It only happens every third or so mowing, but now with each subsequent occurance, the volumn of fluid driping is increasing. Having cleaned everything and looking after each time it has happened, I am reasonably confident it is not the transaxle case, the top fill/overflow valve or any of the hose fittings at the transaxle or hydro motor. I've concluded it must be one of the hoses that is spraying oil on the front lower half of the transaxle case and the other hoses.

My plan is tp power wash again and put it up on stands so I have free access to everything. Failing observing a bad hose, I'll spray talc on everything and try to see where the talc indicates a leak the next time it starts dripping during operation.

I understand that hydrolic hoses have an inner core that is surrounded by a metal weave casing and that is covered by rubber. What sign of damage am I looking for? Is the preasure strong enough that the outside coating is likely to be blown off where the leak is? What other signs am I looking for of visual damage to the hose where a leak would be?

Thanks again for sharing your expertise.

About all I can tell you (not having the opportunity to look myself) is that I expect you will find one or more of the hoses in that group to have worn through the outer rubber skin and possibly through one or both of the steel braid reinforcing layers.
That is an articulated tractor and thus all the hydraulic hoses that pass between the front and rear frame halves bend significantly during turns.
The bending unavoidably causes the hoses to chafe against one another and against the "tunnel" surfaces too.
I have never worked on a Steiner but I have worked around a few articulated front end loaders and the set up is similar (I bet) but using smaller hoses.
If you are prying hoses apart from each other to get a look at them, beware that if a hose is chafed and worn through one of the steel braid layers there are going to be many needle like strands of wire exposed and sticking out like a trap.......so don't run your hand up in there amongst those hoses even with the engine stopped.
A visual inspection with good lighting is the best, use a mirror if needed.
Now, it's possible for a hydraulic hose to be defective and leak without having been chafed and hoses that normally bend a lot in operation (like yours) are prime candidates for that type of failure.
If you do not discover any chafed hoses, you may have to actually remove the hoses from the tractor for a close visual inspection.
Hoses, once removed from the machine can be blown out and pressurized with compressed air. You will need to come up with some fittings to plug one end and to adapt an air hose to the other end of the hydraulic hose.
Pressurize the hose to 120PSI and then spray or mop a solution of dish soap and water on the hose exterior skin.
This is kinda like checking a tire for a leak and will produce small soap bubbles where the leak is. You can also fill a 5 gallon bucket with clear water and then pass the hose through the bucket (by bending it to a loop) slowly while watching for a stream of tiny air bubbles to rise visibly from the leaky spot.
If I had to resort to removing the hoses to test I would for sure take a bunch of pictures of where each hose goes and how it is fastened into the bundle of hoses.
Be a good idea to do one hose at a time to rule out any mistakes.
Darn Steiners are some real brutish looking machines and I hear they have a good reputation.
But I bet not many people are willing to brag about doing hydraulic repairs such as what yours needs.

OP- how much lost leaking fluid are you having to replace ?

Thanks again mownie, Going to power wash, put it on blocks and see what I can find today. Thanks for the advice.

rcbe- Only needing to replace a couple ounces.

One more thing. If you do find damage to hoses, don't think that you must obtain replacement hoses from Steiner.
Take any defective hoses to an industrial hose dealer/supplier and have replacement hoses made.
Hoses obtained in this manner can often be bought for 1/2 the cost of buying through OEM sources.

Update, as I know you are hanging on my every action :) plus gotta do something during my break--I like to take lots of breaks.

Found one hose that has I dime sized chaffe that exposes the steel braid. It was where the hose crossed over another hose (the one that I had observed dripping fluid) just as you predicted . You are kind of scary. Anyway, there is no damage at all to the other hose--it's as smooth as a baby's bottom. The exposed braids don't appear damaged nor does there appear any braid splaying from the force of fluid. But if there is a small pin hole leak there, that was ricocheting off the lower hose, it would be consistent with the areas that were wet with fluid. As I could not see any other hose with damage, I'm gonna roll with this one. Removal looks like a lot of fun. I'll post an update on my next break. (going to find a schematic first to make sure my trace of its route is correct)

OP - Hydraulic systems are extremely particular about staying clean during component repair. Before installing a new hose, purchase a quart or so of fresh quality solvent in a clear plastic container - verify contents are free of contaminants - pour thru new hose assy several times to flush out any loose particles (rubber, steel shavings, etc.) before installing new hydraulic hose assy.
Many of these hoses are made up to custom lengths, but not cleaned internally after being put together - and will mess up a hydro system with contamination before it's own inline filter sys gets a chance to trap the crap.

I can only conclude that the Steiner brothers first determined the size of the tractor and then made everything fit into that volumn. "Reasonable" was not a factor. This could be why new Steiners and Ventracs are so much larger.

I really like my 420. It's built like a tank and is strong and powerful. It also very versitle. Most of all I like its small size, so I'll accept the complications that necessarly result to have those attributes.

Thanks for the heads up rcbe. Taking your advice one step furthar, I used carb cleaner on the fittings and surrounding area to reduce chance of contamination. Will use it to clean the new hose.

Had to buy a knew wrench to get to the fitting and quarters were so close I could barely get it to turn enough each time to get a second biteall the while standing on my head. Took another half hour just to snake the hose out. I fear major headaches in snaking the new one in.

Mownie I was going to take your advice to have a new hose made, but I have concerns about getting a hose that is meant to make all the tight turning radius required. So I'm going to go OEM.

I'm off to the Steiner dealer which is an hour away to beat their closing time.

BTW, I can't believe that there have been so many changes in the hydrolic hose hookup for the Steiner. Considering they have kept the same major components and manufacturers.

If any other tips for installation come to mind, they will be appreciated. I'll check this before I start.

Several come to mind: If you get the new hose successfully installed and go to top off the system fluid levels, make sure to find and follow the mfgr's directions for purging trapped air. Such is usually noted in the owner's manual.
And to do a thorough leak check, you will need to bring the machine up to full operating temp several times.
Good luck.

Done. Now to see if that cured it. Taking some photos turned out to be a lifesaver. Thanks mownie and rcbe. I appreciate your time and advice. It was very useful.