D7G Steering

Our D7G won't steer after sitting for an extended period. This last time it sat about 6 months and when we started it there was no steering in either direction. When it has happened before we were able to get it going by cleaning the magnetic strainer and changing the filter. At other times it started working after just running the machine for a while. This time however we checked the strainer and filter and they were clean with the exception of some small metal pieces on the magnets. Also we could hear the pump and what sounded like cavitation. When the strainer cover was removed the canister was under vacumn and empty. I need to say that when it is working it operates exactly as it should. Just seems the pump loses prime and can't get it back. Can a worn out pump do this?
Does anyone have experience with this problem or any ideas on what to look for?
Thank you.

Buggered pump or sucking air on one of the flexible connections.

Being a DD machine I would want the pump to be working 100%. The pump would lubricate the transmission and some of those gears in the transmission would be near unobtainable these days.

The strainer is on the suction side of the pump, you might try filling the strainer with the engine off, put the cover back on and start it, see if that helps.

Check the connections from the strainer to the bottom of the trans. The rubber lines dry out and shrink and the connections get loose and suck air. Had many old dozers do this. Also a pump can suck air if the seals go bad.

Thanks For the replies. I will check the suction side again as soon as I have time. Suction hose looks good and is flexible. Also want to try priming the pump.

Based on your statement of an empty strainer canister and a vaccum inside it I suggest to remove the strainer again and take a look up the hole it fits in. You may have to go back further than that up the suction lines - like the IKEA instructions "some (dis)assembly may be required"
Do you have something like a shop towel or a rag lodged in there somewhere..?

That pump should be a 2 stage pump with a bleeder line from the pump to the inlet on the oil cooler.
When you start up the pump should self bleed.
If I were checking this I would check the pump pressure on both pumps and if one or both is low pull pump and look inside.
Bob