Steering fluid pressure issue - Does this bend look "constricting"?

p3210 · Sep 29, 2018

Hi All

My first time inserting a pic - I hope it works

I acquired a 1971 massey ferguson mf 135 from a friend.

The power steering fluid has been running hot and blowing seals in a short period of time; twice under my friends owner ship and recently, under my ownership, a power steering pump-hose blew and after replacing both pump-hoses a seal in the power steering cylinder blew after less then 10 hours of fairly light use (dragging sod off a gravel driveway).

The power steering pump is new (installed by my friend a year ago), the two hoses off of the pump are new (I bought the Agco brand), I have been using permatran 821xl in the power steering pump per the dealer.
The service department at my dealer said to look for a restriction in the hydraulic line.
In the photo below is the bend associated with one of the hydraulic fluid metal tubes that travels from the steering column valve (i think thats the correct name) to the power steering cylinder. You hopefully can see that the top of the 90 degree bend is kind of flat - it seems like it could be a constriction...seems a little narrower there. Do you think this could create enough of a constriction to increase pressure and blow seals? .... Or do you think it looks OK and I should look elsewhere for the culprit that is creating the pressure increase?

Any thoughts greatly appreciated

Thanks
Phil

AllDodge · Sep 29, 2018

I don't see an issue with the line, I would look at the steering box, or the cylinder. As with most hydraulic steering you need a valve and return line. There needs to be something that when pressure is applied a valve opens and allows fluid to pass to one side or the other of the steering cylinder. When the steering is turned to where the wheel is where it needs to be, the pressure is released and fluid just circulates back to the pump with only minimal pressure.

In a boat it uses a shuttle valve on the ram and in a car this is dine inside the gear box. Have been unable to find a steering diagram of the 135 so just providing thoughts. What I think is happening. is the valve moves to help steering, but the return back to the pump is clogged. Might need to take the pump apart and clean it up and see if things are moving freely

A pump should also have a pressure check valve. this valve is used to keep pressure in check in case the pressure continues from lets say turning hard and hold wheel tight turn. If the valve does not release some of the pressure things blow and get hot

zzvyb6 · Sep 29, 2018

What is the steering effort like ? And is there a cooler that is blocked with crud. If steering is hard, suspect an internally collapsed hose.

p3210 · Sep 29, 2018

Thanks folks for the quick response

When the steering fluids arent flowing out of the system the steering effort is good - not hard; tractor seems happy. The two hoses that could potentially collapse (that I know of) are new and they are MF Agco hoses so I hope they are quality.

I was hoping the answer would be simple ... like that maybe a slightly crimped metal tube could cause enough back pressure to give me trouble; another photo angle attached just to double check on that theory.
But likely I will have to learn more about the steering "valve assembly" that controls the "power steering assist" when one turns the steering wheel. I believe my friend (previous owner) rebuilt the valve assembly seals when repairing one of the previous leaks. I will have to ask him and see if he will educate me on how that valve assembly works.

thanks greatly for the time and effort
Phil

TractorGuy · Sep 29, 2018

I see nothing wrong with the bend in that tube.

redman135 · Sep 30, 2018

There is nothing wrong with the steel pipes you have shown.
It sounds like you system is being over preassured until it blows.
I had the (power steering) hot oil and seal failure on a MF178, it was caused by an internal valve sticking on. I can't be more specific as the fix was done by the dealer.
good luck