Hydraulic fluid in engine

dls790 · Jun 28, 2014

Hi all - fairly new here but have a real problem I hope someone can help with. I have a 790 that was working fine until the other day- put in reverse and backed up then put in 2nd and it stayed in reverse. then I lost all hydraulics. I took the trans inspection plate off and shifter plate. It looked like the shifter just jammed. Got it shifting again but still no hydraulics. Drained fluid, changed filter and cleaned sump screen, refilled. Still no hydraulics then all of a sudden it had steering then it started spilling oil out the engine oil overflow! I mean it waspouring out of it. I shut down engine went to check oil level and fluid came pouring out of dipstick tube. I checked hydraulic fluid and it did not show any on the stick. Any ideas what is going on or what broke or ????? Thanks Dave S

Gary Fowler · Jun 28, 2014

Sounds like your hydraulic pump blew a rear seal, this allows it to pump oil back into engine crankcase. It might be a simple repair by a hydraulic shop if all else is good. Remove it and take in for repair where they can also check flow and pressure.

dls790 · Jun 28, 2014

Thanks- there are two pumps on this type tractor would I need to take both or just one. If one how would I know which one. Can you explain how the hydraulic system is connected to the engine block? I know in a car ( I've restored old Ford pickups and Austin healeys in the past) there is no connection for the fluid but this tractor suff really has me stumped? dls

RetiredCarGuy · Jun 29, 2014

dls790 said:
Thanks- there are two pumps on this type tractor would I need to take both or just one. If one how would I know which one. Can you explain how the hydraulic system is connected to the engine block? I know in a car ( I've restored old Ford pickups and Austin healeys in the past) there is no connection for the fluid but this tractor suff really has me stumped? dls

Your tractor hydraulic pumps are direct attached drive, so the much higher pressure oil blew directly by the seals and into the engine.

A similar automotive failure would be high pressure fuel pump seal failing on a diesel and filling the engine crankcase with fuel. A simple mechanical fuel pump diaphragm leaking gasoline in to an engine is also a remotely similar condition.

I would check both attached pumps for suspect internal leakage. Talk to an expert on your brand and model tractor first!

Get that hydraulic oil completely out of your engine too. It is not an engine lubricant!

dls790 · Jun 29, 2014

Thanks - I've already drained the oil and gone with a new filter - but have not refilled it as I figured I am going to need to pull the front end off to fix a seal at the pumps. I will try and find someone that knows these compact jd tractors. Thanks again. dls

RetiredCarGuy · Jun 29, 2014

dls790 said:
Thanks - I've already drained the oil and gone with a new filter - but have not refilled it as I figured I am going to need to pull the front end off to fix a seal at the pumps. I will try and find someone that knows these compact jd tractors. Thanks again. dls

DLS,
You are on the right track. Make some calls to tractor shops, land owners with equipment, etc. Folks always like to share a reference or two. Any tractor pulls going on near you? Lots of great information and tractor guys there! I would just not condem and remove the pump(s) until you get some more info.
We could still be wrong on this!
RCG