CASE 450 Hyd, temporarly locked up ?

early 70's Crawler loader / backhoe 450, SN#3064032

While scarfing w/the teeth on the bucket and pushing some small trees & roots, the engine sputtered, lugged down and died. My first thought was that it was fuel related.
Checked the settlement bowl for water and made sure that the petcock was on. All good there. checked for fuel flow / water at the filter drain. all good there. tried to re-start. Motor, (saw the fan), turned over sluggishly maybe 4 revolutions and would stop turning. I did this 4-6 times.
I thought the battery was dying, it's 8 yrs old. So I let it sit for an hour. Tried again, same results.

I jump started it. It started sluggishly, sputtering, but i held the starter button in. Assisting w/the starter. I saw the hyd lines 'shake' and the engine started.

Loader was not in the 'float' position, the backhoe was not on, (been off for a year).

Went through both hyd screens and new tech hyd fluid (OEM) 70 hrs ago.

Crawler ran fine the rest of the day.

I did read in another post where this happened. It was found out that a relief valve had some foreign material in it and was blocking the flow.

Any ideas?

sl

If you have a removable Hoe with hyd Quick Connectors, start there. The hyd flow through the main valve likely exhausts/returns to tank through the Hoe Valve (Power Beyond). Look for badly worn spots in the groove the locking balls sit in. If they are worn the couplings will not be held close enough together to unseat the valves in the ends of them.
Later Bob

Thanks Bob for your input.

The hoe has been off for about a year, and the quick disconnect is coupled together. I'm not sure, but I don't think it will run disconnected. :roll:

I know the valve you are talking about inside the quick disconnect. If it were worn, would it leak?

sl

MAKE sure they are coupled together just because they look like they are i bet they are not

Steve, the quick connectors have basically a check valve in the end of them to keep the oil from leaking when apart. They have an equal strength spring behind each of them to keep them close and ensure that both open when coupled together to allow oil flow. To make the check valves open fully they must come completely together and be locked there. The most likely cause of intermittant flow restriction would be a worn lock ball groove. If balls are in a worn spot the valves would be closed or less open than if the lock balls where in an unworn spot in the groove. If you happened to twist those connectors that might be why the machine worked fine after. Another thing but not an intermittant problem is if the spring retainer inside breaks or slips back causing a loss of equal spring pressure. Then you have an inline check valve and not know it. The only you find out is if the flow is going against it. This happens in a flow meter setup when hoses might be installed with flow in different directions at different times. Happened to me once. Doing a pump only flow test, no relief valve. Started the engine and the oil couldn't even get to the flow meter to blow the safety disc. The hose from the pump got a tremendous erection and lifted the flow meter up in the air. Thought I had ruined the pump but it was a piston pump and the barrel blew off tyhe port plate and saved everything. The snapring behind the spring had got out of place and just waited untill I hooked the hose up the wrong way. Hooked up the other way the oil pressure would have opened the check valve.Unhook one connector and try to start the tractor, see if the symptoms are the same as you had.
Later Bob

Thanks guys! Great advice. I will be looking into this. If I find anything, I'll post back.

Thanks again, I never would have suspected the Quick Coupler...sl