2012 Hino 258 Clear/Light brown Oil in air tanks?? Air pressure problem?

likemlow

Seasoned Expediter
Mechanic
Hi all,
Must be a weird week for Hinos. Our 2012 Hino 258 Has a lot of this clear to light brown oil coming out of the air tanks and we have no idea where its coming from. It looks like hydraulic fluid. The driver of the truck said he started noticing it a couple weeks ago when he would periodically drain the air tanks. He brought the truck in when the air compressor went out and started blowing air into the cooling system. We've had the compressor rebuilt and have replaced the Air dryer assembly. Now we have two problems- After putting everything back together, the air pressure won't built up unless we put shop air to the governor line into the air compressor. We removed the compressor again, took it back to the re builder. He hooked it to a machine and showed me it is building pressure. We reinstalled it. The air pressure wont build up at all on its own. And we still have the oil coming out. Thanks for any input it's much appreciated.
 
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BigStickJr

Veteran Expediter
Retired Expediter
Have you replaced the air governor ?
You can unhook the line coming off the compressor to be sure it’s pumping on your truck.
If so, check output pressure.
If good, just start working downline. See where it stops.
Somebody more mechanical may come up with a better answer.....
 

greasytshirt

Moderator
Staff member
Mechanic
I agree, sounds like a governor issue.

If you look at the air intake, the crankcase breather tube and the compressor Inlet tube are very close together. It's not uncommon for crankcase gases to enter the air compressor, causing black oil to show up in the air dryer. Oil that looks like hydraulic fluid? No idea.

Sent from my XT1585 using EO Forums mobile app
 

BigStickJr

Veteran Expediter
Retired Expediter
When I read hydraulic fluid I thought pink AF ?
Maybe mixed with a small amount of residual oil.
 

likemlow

Seasoned Expediter
Mechanic
67fluid.jpg 67fluid2.jpg
Here's the fluid coming out of the air tanks. We were able to fix the air compressor problem by switching the head of the compressor with another one and it started working normally. It seems the "reed valve" inside was getting stuck open. But this fluid has me stumped. :think3:
 
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