Hey everyone, long time lurker...first time poster. I've been able to get by up until now based on all of you guys wealth of knowledge, but I need an opinion here. I have a 79 410D with about 5400 hours on it. Last week, I noticed that the loader would start shuddering a little when I raised it off the ground with or without a load. At the same time, it would almost feel like it was choking out the engine a little bit. I also noticed a knock near the front pump coupler almost in cycle with the engine. Steering is working, but a bit jerky. Am I on my way to a new front pump here, or is there something else I should be looking for? I know just enough about hydro systems to be dangerous, so I don't want to go stick a pump in this thing if it doesn't need it. Thanks!
Take a good look at the crankshaft to pump coupler etc. use a pry bar to get in there and wiggle stuff until you're satisfied it's all in good shape, nothing loose or broken. That knocking could be caused by low oil supply, not the pump itself or the drive. Check the fluid level, condition of the fluid (is it milky or foamy while running?) When did you last check the suction screen? change the fluid? Before doing anything to the pump, check the charge pressure on the supply to the pump.
Update Thanks Delmer, I finally got some time today to work on it. I inherited this machine as part of my property purchase. The previous owner said the fluid was somewhat new, but after it started acting up I drained the fluid and swapped the filters. The filters were not JD filters, but they are now. Since I did that, the shuddering has gone away on a few test raises...and I started getting some small leaks in some connections that had probably loosened up a little over time. So, my guess is flow was somewhat inhibited. I haven't put a load to it yet. The noise however, is still there. I checked where the coupler meets the crank, and all is tight and seems fine. The knocking sound definitely sounds like it's coming from the pump, and I can feel the vibration when I put a hand on the front tire. When I start the tractor, there is no noise for the first few seconds of operation, which makes me think it's when the pump kicks on and goes under load. The engine itself burns no oil, and is probably the cleanest diesel exhaust I've ever seen. Could the bearing in the pump itself that meets the coupler be going bad? Would the next step to be to toss a pressure gauge on it?