675 DTC hydraulics jumpy

Tim D · Sep 4, 2009

I have a Farmtrac 675DTC and the hydraulics are jumpy. When you pull hyd/tran stick without tractor running, the oil looks fine, but while it is running the oil looks to have air in it. I think that it was either cheap oil with no anti-foaming agents or I am sucking air on the pick-up side of pump. Also, I am getting ready to change trans/hyd oil and wondered if it would be good to run some sea foam through system to clean it out before draining. Any input would be greatly appreciated.

Charolais · Sep 5, 2009

Tim D said:
I have a Farmtrac 675DTC and the hydraulics are jumpy. When you pull hyd/tran stick without tractor running, the oil looks fine, but while it is running the oil looks to have air in it. I think that it was either cheap oil with no anti-foaming agents or I am sucking air on the pick-up side of pump. Also, I am getting ready to change trans/hyd oil and wondered if it would be good to run some sea foam through system to clean it out before draining. Any input would be greatly appreciated.

Does your tractor have 1 or 2 hydraulic filters? Does it dump the return oil in the top or bottom of the housing? I have a 80 which was later changed to 675. It has 1 filter for steering and hydraulics for the rest of the tractor. Later there was an upgrade and those had a filter for the steering and one for the rest of the hydraulics on the tractor. Also I had problems with oil foaming. Farmtrac back then had great service from Tarboro and my dealer is great to work with too and still is. They rerouted the pressure return line from the bottom (dumping) to the top and that stopped the air bubbles from forming. My dealer put that on without charge. It's pretty simple to do. Just remove the hard line where it dumps in the bottom and plug it off and run a hydraulic hose from the pressure return(dump) up to the top port that wasn't used. It's located right behind the top link standing behind the tractor. I still had a little foaming problem when running the wood splitter. I then added a vent(breather) using a small oil filter to another port that wasn't used and that stopped the foaming when splitting wood. What I found was the little hole in the fill cap wasn't large enough to vent the system proper. I work in the wood industry and all our hydraulic units have an air filter for breathers. It works great on a tractor too and keeps the air clean going in and out.

Tim D · Sep 5, 2009

Thanks Charolais. This tractor has 2 filters, one for steering and one for hydraulics. Sitting inside the house I think the return dumps into top of housing. Will check as soon as I can get my lazy rear end out.

kennyd · Sep 5, 2009

If it "looks like air", it probably is, and it can ruin your pump in a hurry. Air usually comes from a leak on the return or suction side of the pump-and often there is no external leakage making finding it very hard.

Tim D · Sep 6, 2009

Tractor has two sumps in belly. One for hydraulics and one for steering. Both sump lines go to seperate filters and then to their designated pumps. The line from hydraulic pump starts to go back to remote outlet blocks, but is seperated off and feeds loader valve. From loader valve on the power beyond side, it first goes to the remote blocks and then goes to run the 3 point hitch. There is also a dump line from loader valve that goes into rearend housing at the top and dumps. Did not look to see where excess oil from steering goes. I have tightened all of the fittings and even put blue silicone around fittings on sump lines. Steering will jerk occasionally if you turn real quick, but not all the time. Did drain oil and changed filters and found a large glob of paint on filter base for hydraulic filter where gasket would seat. Do not know yet if this is where air was entering or not. Have not replaced oil yet as I had to go to my paying job.

Tim D · Sep 8, 2009

I wanted to update what I have found out about the jumpy hydraulics. I drained oil the other day and while looking at the oil filter base for hydraulic side, I noticed a large clump of hard paint that was a little more than a 1/16 in. thick where the filter gasket would ride up on it. Potential place to suck air. Went ahead today and put new oil in it's belly with 10% mix of Lucas oil treatment. When I was close to having it full, I started tractor and and hit 3 point lever and to my pleasure there was no jump in lift arms. Next was the loader and no jump there. I had also noticed rubber lines going to and coming from loader valve jumping on regular bases when running around 1500rpm and greater. No more of that either. Took tractor on road test to really churn oil and everything seems to be working way faster with no jump. So it looks as though it could have been air leak from paint, possibly gummy filters that were reducing flow or the oil that was in it. Either way I am glad I changed oil at 110 hrs. instead of the 1200 the book states. As the old saying goes, even a blind hog gets an acorn every once in a while. Maybe this runt just got one.