Wirlpool washer won't fill keeps draining

I have a Wirlpool Heavy Duty washing mashing, model LA5550XTW0 that has all of the sudden started to continue to drain regardless of water temp or size of load instead of filling. It's like there's a valve that just doesn't close so the water runs right through it to the drain. I've had it completely drain my hot water heater several times. Most of the time if I turn it off and on several times and maybe let it go through a few seconds of part of a cycle whether it's agitate, rinse, spin or whatever it will start to hold the water and I'm able to use it, but occasionally after the water from the agitate cycle drains and it's gone through the first spin cycle and it starts to try to fill for the rinse it will develope the same problem where it won't hold water and just lets it all drain out . Is this something that can be fixed? I'm not concerned about ease, I'm savvy with my tools, I just know alot more about cars and computers, but would like to do this if I can. Please advise.

I'm not sure if it's a direct drive or belt drive. I read in a thread that I can't seem to locate that one has a solid back piece and one has an access panel. Mine has the solid back.

 

Your washer may be syphoning. Make sure the drain hose isn't stuffed too far down the standpipe, or that the drain hose height isn't below the water level.

 

AFTER YOU CHECK WHAT SCOASH SAID .. AND YOU HAVE NOT DONE ANYTHING DIFFERENT TO THE DRAIN... IT IS MOST LIKELY STARTING TO CLOGG UP.. NOT LETTING THE AIR POCKET FORM BETWEEN CYCLES.. ON OLDER MACHINES YOU COULD CLEAN THE LINT SCREEN NOW IT ALL GOES INTO THE DRAIN.... HAVE SEEN THIS HAPPEN MANY TIMES... RUN A SNAKE AND DRAINO THRU AND WILL PROBABLY TAKE CARE OF IT

 

I wish to thank Scoash for his advise which I followed and succesfully resolved my problem "Wirlpool washer won't fill keeps draining”. When the problem did not go away by itself, I was thinking of calling a wash machine repair service or even buying a new wash machine. Instead I looked up on the internebt and found a posting with the excact symptom and how to resolve it.