Jinma(Nortrac) 304 leaking hydraulic into engine oil?

   / Jinma(Nortrac) 304 leaking hydraulic into engine oil? #1  


New member
Apr 27, 2024
Nortrac(Jinma)304c, TY395E
It is a 304B by nortrac with T395E engine. I recently refilled my lift hydraulics and it seems to have leaked hydraulic fluid into the oil enough to blow the dipstick out under pressure with the engine running away and blowing oil and smoke. Hydraulic fluid was almost completely gone after that. Changed the oil and filter and got way too much diluted oil out. Drained what little was left in the hydraulics. Filled the water and diesel to capacity to rule those out although it was pretty clear filling the hydraulics caused the problem, and now the engine is running fine with no unexpected drop in the fuel or water.

Where can the hydraulic fluid be getting mixed into the oil and how to stop it? The steering hydraulics are separate from the lift, so I can run the tractor and even use the bushhog (not optimal because I can't lift it) but I can't use the FEL. I'd like to get the hydraulics back if possible.

I'm attaching the 2 cylinder block diagrams because the 304B(EPA) is not as complete as the 304(nonEPA)

Thanks for any help.


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   / Jinma(Nortrac) 304 leaking hydraulic into engine oil? #2  
The hydraulic pump shaft seals is leaking. Since it's mounted to the engine, it leaks to the engine, over filling it and causing the issues you're experiencing.

Time to pull it out and change the seal.
   / Jinma(Nortrac) 304 leaking hydraulic into engine oil?
  • Thread Starter
Thanks for answering so quickly, but can you translate for a non-mechanic? If I can find the right parts to order, I can usually figure out where to put them. I see a bushing where the pump shaft enters the block, is that the seal? Or am I completely looking at the wrong place? Thanks again!
   / Jinma(Nortrac) 304 leaking hydraulic into engine oil? #4  
Here is a picture I pulled from the internet. Maybe it helps visualize the issue. The part #7 is the shaft seal. If this seal leaks, since the pump is mounted to the engine timing cover, it will send hydraulic to the crankcase, over filling the engine, till it runs away or starts blowing the dipstick out.

Essentially, you'll need to pull the hydraulic pump out, take it apart, take the seal out and replace it. For the seal, an hydraulic shop should be able to match it.

If you end up doing this work, make sure you put all the parts in the same place and in the same orientation. I typically mark the front flank, the body and the rear cover with a punch.
   / Jinma(Nortrac) 304 leaking hydraulic into engine oil?
  • Thread Starter
Thanks very much, now I understand. I changed that pump before all of the trouble started, because my hydraulics weren't working when the fluid was full. I'd hate to think I got a defective one. It was a pain to change and I really don't want to have to take it off again. I think I'll go out and just stare at my tractor for a while....