Engine Oil Leak

[st0ck1ng]

1989 L785 with ~7,800 hours

Recently developed a leak on my NH L785.

Found leak evidence around the oil pan gasket with most concentrated at the rear of the engine.

Replaced the oil pan gasket which significantly reduced the amount of oil being lost.

But still have a leak where the engine/hydraulic pump connect.

As it is appears to be fresh oil, from the replacement of the gasket, I am assuming it is the rear main seal.
- Not a steady stream, but several drips per minute (see attached) my guess would be about a quart of oil per day. So nothing I cannot manage for the time being.

Machine uses 10-30 for hydraulic fluid, COULD there be a leak in the hydraulic system that I am just not seeing, any recommendations on how to further isolate the leak?

ONLY leaks when running, ie shut down, leak stops relatively quickly.

It appears no one has ever been in this engine before.

The engine DOES have some blow by pressure in the oil pan, BUT, i added a pressure relief fitting/filter in the unused dipstick port to relieve pressure buildup which helped also.

If consensus is rear main seal is culprit, I will likely baby the machine for this summer (to many projects to get done) and then do a complete rebuild on the engine over winter, to account for the engine blow by AND the rear main seal at the same time.

If there is a leak source I am overlooking, I will try to locate them immediately.

Thank you in advance for any/all support/thoughts.

 

[fortworth-cowboy]

You said it is where the engine and hydro connects, is it Hydraulic Oil then its the input shaft sela from the hydrostatic pump, if its engine oil its the rear main seal from the engine.

 

[st0ck1ng]

FWC, Thank you, is there an easy way to differentiate between the two possible sources?

 

[mrbb]

add some oil dye to one or the other and see if it shows up leaking out! they sell it at most larger chain auto parts stores!

 

[st0ck1ng]

Thank you, completely forgot about oil dyes.

Feeling a little foolish.

 

[foton]

if there is no fluid loss in your hydro system and loss in the engine oil,well it is the engine oil.

 

[fortworth-cowboy]

add some oil dye to one or the other and see if it shows up leaking out! they sell it at most larger chain auto parts stores!

Well unless he just did a oil change, you should be able to tell if its hydraulic oil or engine oil without any dye.

 

[mrbb]

Well unless he just did a oil change, you should be able to tell if its hydraulic oil or engine oil without any dye.

well on many of these older machines, they use Motor oil in both systems(10w/30) , motor/engine, pending what one prefers to call it,(HAHA) and hydraulic system,
so fluid leaking would be the same, minus if you added dye to one,. t ?
NOW< if someone altered things and started using Hydraulic fluid in it over what the OEM calls for, well, then?? yes, I think there should be a difference in smell and color or??
BUT again, adding dye, will also, make this easier on folks that don't know the differences or experience id' ing them by sight/smell in its original form! !

 

[st0ck1ng]

FWC, MRBB,

Thank you for all the help and support.

This machine does use 10-30 as hydraulic fluid and it is clean.

Verified it is hydraulic fluid, BUT, it is coming from under the pump and running back to the area under the rear of the engine.

Leak finally got bad enough I can now see the oil flowing, cannot see the leak, as it is up under the pump.

Now I am trying to find videos on how to access that area, so far have not found much.

Appears the only way to go is pulling the pump out.

Again, thank you for the help!!!

 

[tech.35058]

I am not familiar with the L785.
On my Lx865, I found the bolts holding the pump to the drive housing loose, pumps leaking oil at the input shaft seals, & the rear engine support bushing/rubber mount deteriorated/squashed, so the pump was rubbing against the frame ( had actually rubbed a hole in the frame, but not the pump yet)
On my machine service manual instructed on how to tip the cab to get access, but tool no longer available. I ended up fabricating the tool. Good Luck. CE

 

[st0ck1ng]

FWC, MRBB,

Ok, looking for a straightforward assessment.

Still have my hydraulic leak after replacing the seal between the yoke and the pump.

So the question, how difficult is it for a do it yourselfer to do a complete rebuild on the hydraulic pumps, ie gear/front/rear pumps

 

[mrbb]

FWC, MRBB,

Ok, looking for a straightforward assessment.

Still have my hydraulic leak after replacing the seal between the yoke and the pump.

So the question, how difficult is it for a do it yourselfer to do a complete rebuild on the hydraulic pumps, ie gear/front/rear pumps

honestly I couldn;t say, never had to do that on a LX 865

as for tipping the cab, , I did have to do that once due to a leaking hose I couldn;t get to any other way

I didn't have the OEM tool, , and I also have a aftermarket heater set up , that added steps to tipping cab
I used a back hoe to lift boom and tip cab, as happened to have access to one where I was doing repairs, it wasn't that hard to do so, but was time consuming, and I did it in dead of winter when temps were in the teens, in a non heated building
I did use some torpedo heaters as it was dam chilly at times, and I ain't as young as I once was to tolerate cold like I used too!

I also replaced all the hoses that were now easily accessed while cab was tilted,
but sadly one of the hoses was mad short and was rubbing, and didn;t have time to waste to have remade(now wish I did)

as it has since rubbed thru the one layer on two other hoses on me now, and soon needs to replace all 3 now!!
I thought they would last longer, but not so lucky! Haha
its amazing how much stress is added to lines when under pressure , to rub thru so fast!

as for rebuilding your pump, I guess it comes down to your skill level and comfort, but I doubt there is anything too tricky about them,
if you have a service manual, it will show steps and how too, plus, even provide a HR time chart for service charging, to give a idea on repair time, maybe for you to consider?

 

[st0ck1ng]

MRRB,

Thank you for the thoughts.

I have replaced all the hydraulic hoses from the pumps out to the various drives
- boom and bucket hoses are all that remain and are in ok shape.

 

[st0ck1ng]

Bottom line my hydraulic leak continues, BUT, wasn't so great I couldn't "ignore" it until winter when I could do more about it.

That said, I noticed the other day that the leak has almost stopped, ie hardly anything on the cardboard I keep under the machine.

The only thing that has changed is the hydraulic reservoir level, which is currently just barely touching the dip stick.
- This made me remember that this leak started AFTER filling the reservoir to the level as indicated on the dipstick, AFTER losing a hydraulic pump seal.

EVERYTHING operates as designed, no issues with any aspect of machines capabilities/maneuverability etc.

I am beginning to think the dip stick is NOT original and therefore filling the reservoir to the level it indicates is creating a hydraulic over pressure problem.
- I know this happens in an overfilled engine, CAN it happen in an overfilled hydraulic system?

Any thoughts appreciated.

 

[mrbb]

or could you maybe have a hole in the tank, and once below it it stops leaking ?
just remember running pumps low can get really costly,~

 

[st0ck1ng]

MRBB,

Thank you for the response and thoughts.

There is not a hole in the tank, the hydraulic leak is definitely at the pump seals, the fluid leak is at the connection of pump with the yoke.
- To be fair, I am NOT certain there is not a bad seal in the rear piston pump assembly as I wasn't smart enough to check it also, so it may be that the front pump is trying to handle the pressure from both pumps.

But that still plays into my question of, if the hydraulic tank is overfilled, does that create a potential for over pressure

There is no indication of the pump lacking for fluid.

 

[brdgbldr]

MRBB,

Thank you for the response and thoughts.

There is not a hole in the tank, the hydraulic leak is definitely at the pump seals, the fluid leak is at the connection of pump with the yoke.
- To be fair, I am NOT certain there is not a bad seal in the rear piston pump assembly as I wasn't smart enough to check it also, so it may be that the front pump is trying to handle the pressure from both pumps.

But that still plays into my question of, if the hydraulic tank is overfilled, does that create a potential for over pressure

There is no indication of the pump lacking for fluid.

First of all I am not familiar with that particular machine.

Most hydraulic tanks have breather valves or caps on them so the only way that you could get over pressure is if it is clogged up.