743 hydraulic leak

[daved]

I have a 89 model 743 and I seem to of sprung a leak. I cant tell where exactly because its running down the inside of the belly around the pump or maybe valves. I havent had time to try and pressure wash inside there but if I look in the engine compartment there is fluid on both sides of engine, more on the right side than left but it trickles back there makes a mess. I parked in the garage yesterday after it was warmed up and it must of leaked a quart of fluid out overnight but quits once it sits. Id say over 2 weeks its probably leaked 2 gallons and wasnt used much. The only thing I can see fluid on is the big 1 1/2 return line? on top the pump but it doesnt look like that big of a leak. Whatever it is its fairly slow so I dont think its high pressure, It doesnt seem overly wet around valves Is there anywhere 743's are more likely to leak like this that I can check harder? In the meanwhile Ill try to degrease and clean up down there, Its going to be a nasty job, maybe my little cousin needs some extra money ha ha Thanks and any input to help me find my leak would be helpful. Oh and I had my dad help me look in the engine compartment while I moved loader up down and bucket and aux's thinking maybe a hose that goes through loader frame but no geysers back there. Thanks again for the support.

 

[Tazza]

No one can tell you exactly what it is without seeing it. There is nothing that stands out as being an item that leaks a lot. There are a few things, but from what you said it sort of rules them out too. Ok starting from the top!
Put the machine on level ground and remove the plug on the chain case at the front where the bucket sits. The oil level should be level with the bottom of the thread of if you can feel oil with your finger the level is rite. If its over full you have a leaking seal on a drive motor. This will cause oil to leak out under the pump as there is a breather there.
So thats possible cause 1
The next one could be the rear seal on the pump, its under charge pressure thats around 90-120 PSI so you can loose a bit of oil back here. If your U-joints are bad they may have damaged the bearing in the pump and damaged the seal. The seal on the swash plates on the pump could be bad too, easy to swap though. A tube line could have worn though or rusted out that run behind the chain case between the blower housing, you build up crud back here and they can rust away. You get pin holes and oil goes everywhere. The other cause can be your lift rams or hoses to the rams. Where they pivot they can sometimes rub on the frame wearing through the welds. If thats the cause you should see oil dripping down the side of the frame though. Remove the ram and grind the weld out and weld it back up, works a treat did it myself a month ago.
Honestly, the best way is to give it a really good de-grease and pressure wash. You may need to do it several times to get it clean. When its pretty good see if you can locate it. You can look for where its wet and naturally oil can't go against gravity when the engine is off so look no higher than where its wet.
The oil cooler is a possibility but if you remove your inspection covers on the blower housing above the engine you should see oil if it was leaking there. Even your reserve tank may have cracked where the fitting screws in at the base? or simply need an O ring.
Give it a good clean then keep searching, thats the best advise i can offer. Know you are NOT alone, i have had a nightmare job trying to find a leak before. Just be patient, you'll find it!
Don't be afraid to pull the engine either, its not as hard as it may seem if you need to gain access.