Skip to main content ↑ ↓
Topic: Hydraulic oil tank is always wet (Read 580 times) previous topic - next topic

Hydraulic oil tank is always wet

The hydraulic oil tank on the left of the engine bay above the air filter is always wet down the side. Not dripping wet just wet. I don't think this is normal but I haven't figured out where it is coming from. Anyone else have this happen and how can I stop it???
The selected media item is not currently available.Keith & Jo
2003 U320T 4025 PBBS Designer series
Build 6203    Cummins 500hp
2000 U320 4010 WTFE / Build 5762 —Sold—
Motorcade #18070   
Pasadena, Texas
2015 Jeep Wrangler Sahara-Sunset Orange pearl coat
Don't argue with a fool, people watching might not be able to tell the difference.

Re: Hydraulic oil tank is always wet

Reply #1 –
Does this happen sitting and/or moving?,put a towel temperarily over the tank and see if the towel gets wet from above,it may
also be a temp difference,make sure it's water and not coolant.
96 U270 BUILD 4810
85 380SL
Drummonds TN.

Re: Hydraulic oil tank is always wet

Reply #2 –
Keith,

Can you determine if it is oil?
If so check to see if the tank has been overfilled. Pull the dip stick and give it a look.
It could be the top gasket seeping when your engine is running and circulating the hot oil.
The gasket number should be 999-55A
 You really need to check and see how long it has been sense the oil and filters have been changed. Change oil, filters, and gasket if you find that it has been a while.
Check the hoses to see if one of the hoses has a seep either at the threads or on the hose where it has been rubbed and a hole has developed.

Pamela & Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Hydraulic oil tank is always wet

Reply #3 –
Quote from: Pamela & Mike –
Keith,

Can you determine if it is oil?
If so check to see if the tank has been overfilled. Pull the dip stick and give it a look.
It could be the top gasket seeping when your engine is running and circulating the hot oil.
The gasket number should be 999-55A
 You really need to check and see how long it has been sense the oil and filters have been changed. Change oil, filters, and gasket if you find that it has been a while.
Check the hoses to see if one of the hoses has a seep either at the threads or on the hose where it has been rubbed and a hole has developed.

Pamela & Mike

Good advice.  Suspect gasket is bad or oil overfilled.  Pretty simple and inexpensive in either case.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Hydraulic oil tank is always wet

Reply #4 –
A new "O" ring is cheap. I have a spare. My hydraulic oil tank always seemed to leak a bit too until I discovered that the two halves of the clamp ring were installed wrong (flip one side end for end to fix it) and it wasn't actually clamping very well.  Swapped ends, cleaned it all up. No more wet and dirty sides on the tank.
Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: Hydraulic oil tank is always wet

Reply #5 –
Guess I thought "wet" meant moisture,oil leak a whole different animal,is it "wet" below the oring?
96 U270 BUILD 4810
85 380SL
Drummonds TN.

Re: Hydraulic oil tank is always wet

Reply #6 –
This sorta shows the wetness so I think the gasket may be the culprit
The selected media item is not currently available.Keith & Jo
2003 U320T 4025 PBBS Designer series
Build 6203    Cummins 500hp
2000 U320 4010 WTFE / Build 5762 —Sold—
Motorcade #18070   
Pasadena, Texas
2015 Jeep Wrangler Sahara-Sunset Orange pearl coat
Don't argue with a fool, people watching might not be able to tell the difference.

Re: Hydraulic oil tank is always wet

Reply #7 –
I don't think the oil level should be so high that the o-ring comes into play, sounds overfilled. So easy fix. Woops didn't read the whole thread again.
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake

Re: Hydraulic oil tank is always wet

Reply #8 –
Keith, the clamp looks like it is on correctly.  These was a bit of rust around the gasket seats on mine.  Clean any up with sandpaper and try a new gasket.  Make sure it is not leaking around the dip stick/fill tube cap.
Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: Hydraulic oil tank is always wet

Reply #9 –
Oil cap should also have a vent for expansion and contraction
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake

Re: Hydraulic oil tank is always wet

Reply #10 –
Top is dry, dip stick doesn't show overfill, but the wetness starts below the gasket mainly on one side
The selected media item is not currently available.Keith & Jo
2003 U320T 4025 PBBS Designer series
Build 6203    Cummins 500hp
2000 U320 4010 WTFE / Build 5762 —Sold—
Motorcade #18070   
Pasadena, Texas
2015 Jeep Wrangler Sahara-Sunset Orange pearl coat
Don't argue with a fool, people watching might not be able to tell the difference.

Re: Hydraulic oil tank is always wet

Reply #11 –
When you put in the cap and tighten it up it expands a rubber seal. Keith, time for a new O ring gasket.
Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: Hydraulic oil tank is always wet

Reply #12 –
Roger does your top bung hole appear to align with dip stick markings? His dipstick may have been substituted
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake

Re: Hydraulic oil tank is always wet

Reply #13 –
Dip stick has low and fill marks, maybe hot and one side and cold on the other, not sure if I am remembering that part.  It does not look long enough to align with the sight glass which looks to be lower than the dipstick. I can go look in the morning to see if my memory is still good.  I have changed the oil and filters once in 6 years.  Another year or two and I will do it again.  I have a small weeping leak on my steering box (getting it fixed this winter) and in all of those six years I have added a quart and a half to the tank.  And when I changed it it looked like brand new oil.  I am changing oil and filters every four years.
Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN
 

Re: Hydraulic oil tank is always wet

Reply #14 –
Your oil leak is most likely from the site glass on the side of the tank.  It is probably loose-- mine was and had a seep leak around the gasket.  Just give it a slight clockwise turn by hand, that should do it.
Current coach 1996 U320 40'
Previous coach, 1990 36' U280