55 series hydraulic pump noise?

[jd4310man]

I got an 87 655 and everything works as it should but am wondering if its normal for the hydraulic pump to be noisy? It sounds like its got a wine like air is in the system. I changed the oil and filter, cleaned the suction screen. Is the pump just noisy by nature? I have no prior experience with these older hydro tractors as all the new ones i had made no such noise.

 

[texasranger556]

Its been years since I drove a 55 series but I do remember them having more of a "whine" than my 4000 series does. You can try YouTube to compare, here is one example john deere 655 755 mower front loader - YouTube

 

[jd4310man]

texasranger556, Thanks for the link, Yea that one on the video sounds just like mine. It must be in the hydro pump at the rear of the transmission making all the noise.