Washer, drain line

QUESTION: The house I live in was built in 1979 on slab construction. I’ve had the plumbing checked for blockage as well as the roof vents checked and they are clean and open. Two years ago I replaced the toilet flanges with stronger ones, and the wax seals as they were leaking sewer gas. Now when the clothes washer empties on a large load, the toilets gurgle, the water level moves up and down and if the toilet is flushed during this period it is slow to drain. Other than when the washer is draining, everything works normally. All the lines have been rooted twice to the street and they were clean. Is the issue that modern washers overwhelm 1979 plumbing, or do I have something else going on? I considered having the lines videoed but the cost seems way too expensive. The county checked the county section with video and it is fine. I looked online for simple solutions and saw others that have this same issue but no one found the culprit.
Steve Kent, Citrus Heights
ANSWER: “It sounds like you have a restriction in your main line some where between the point where the laundry line connects with the toilet and the county connection,” says Vince McDonald, owner of McDonald Plumbing, Heating and Air Conditioning in Sacramento.
“If you did not have the main drain under the house cleaned when the drains to the street were rooted, that would be your best next step,” he says. “If you still have problems after having that done, a video inspection would be step number two. The cost of a video inspection may seem high to you, but it beats the heck out of jack hammering up the floor and digging up pipes to see what is going on!”
“Video cameras have become an invaluable tool for all professional service/repair plumbers. Prior to the video systems, we did our best with the tools available, but without the needed diagnostic information, the service to the customer and the cost to perform the work suffered. Cameras have now been around for more than ten years and the cost to camera a line has come way down.”
“I wish I could just blame the age of your house and the new high volume wash machine for the problem, but that is not the case,” he says. “A plumbing system that is properly installed and is clean will not have problems as you describe. A plumbing professional with a good camera and well versed on plumbing waste and venting systems should be able to get you fixed up or at least inform you of your options.”

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