80W90 or Coop Trans Hyrdraulic - difference??

[dourobob]

I recently changed the fluids on my MF FE 35 and I have noticed a big difference (increase) in the 3PH leak down. When I bought this tractor last December I ran it until it was quite warm then shut it off. The 3 PH held up a 6.5 foot snowblower for about 10 -15 minutes before slowly leaking down even though the hydraulic fluid was not topped up - I don't know what kind of oil ws in it when I bought it. The temperature on that day was about +5C (+44F), it was sunny and we were out of the breeze.

Last weekend, with brand new CO-OP Trans Hydraulic fluid filled to proper level, the 3PH will leak down in about 30 seconds with a light 5 foot cultivator on it. Now I am hearing that I really need to put 80W90 in the transmission.

What is the difference in these two oils??

Could this be a pump issue rather than an oil issue??

Thanks for any ideas.

Bob

 

[gatractorman]

Not entirely familiar with your tractor but, the regular old straight gear drive trans. would love 90 wt. but if the hyd. pump gets it's oil from there then it will be too thick, the trans/hyd. oil would be what to use in this case, it sounds to me like you may have an internal leak mabye piston seal or a safety valve I dont believe it would be the pump as I'm assuming it still works ok other than the leaking down.

 

[Anonymous Poster]

The co-op fluid is probably about 20W or 30W , which is a lot thinner than 80W90. Not sure what kind of fluid your tractor takes though. the 90W is NOT normally used in hydraulics, but it is possible that is what you tractor uses, check with a dealer.

 

[neilw]

I do not know what your application calls for. However, be careful when comparing SAE grades of oil by weight. SAE uses different weight number for crankcase oil and gear oil to reduce confusion and prevent people from using gear oil in an engine and engine oil in gear applications.

For example using ISO 46 graded oil at a cSt @40*C. compared to SAE grades.

SAE crankcase oil graded as SAE 20 cSt @100*C = ISO grade 46 cSt@40*C

SAE gear oil graded as SAE 80 cSt@100*C = ISO grade 46 cSt@40*C.

So an 80w gear oil is not more viscus than a 20w crankcase oil.

 

[JohnMiller3]

<font color="blue">...Could this be a pump issue rather than an oil issue??... </font>

Starting to sound that way... /forums/images/graemlins/shocked.gif

 

[dourobob]

Ouch - John, I know you had had MFs in your past so you are probably well aware of the application here. Guess I have more exploring to do with the manuals and a couple of experienced (now retired) MF mechanics (Big Dean for example).

Thanks
Bob

 

[JohnMiller3]

<font color="blue">... (now retired) MF mechanics (Big Dean ...</font>

Hi Bob,

Big Dean should be able to walk you through with a couple of quick tests and confirm this...

If Big Dean can't solve this... then it can't be SOLVED! /forums/images/graemlins/wink.gif

(say hello to Big Dean for me...) /forums/images/graemlins/smile.gif