Got a CAT 320 suffering from power loss under load, as soon as you try to dig it sounds like its stifling and if you keep pushing it, it will eventually stall. If you allow it to recover, you will see a puff of blue smoke and it will idle ok until you try digging again. The second machine will exhibit the same symptoms except this time you will see black smoke. Anyone experienced this or have any idea what causes it?
Check air and fuel filters, when you change the fuel filters take the opportunity to blow the suction line from the tank, it can be full of crap. If that doesn't help continue with checking boost and fuel pressure and if there's air in the return line.
Fuel and air filters are good, one uses two fuel filters. Removed the tanks and cleaned them, water separators are checked daily. Also not sure if this means anything but running the machine in Heavy mode seems to help, not sure if this ( runnig in heavy all the time ) is safe though?
Hi JVS Cat excavators have a device called a powershift (not to be confused with the type of transmission) on the hydraulic pump. This acts to reduce swahplate angle and thus hydraulic pump displacement when the engine lugs down, to prebent engine stall. If this is working okay it should be impossible to stall the engine, it should (throttle position 10) lug down to perhaps just below 1700 rpm then stabilise around 1800 until you release the joystick. The powershift valve is on the top left-hand (drive) side of the hydraulic pump, just to the left of the left-hand high pressure pipe (as you face it through the access panel), with a two-pin plug in the top. It can be as simple as a wire out of the plug, or a loose pin, a break in the loom (it goes back to the machine ecm - check the pins in the interface as well) or it could be that the poweshift pressure needs to be reset, which can be done through the monitor in the cab - you'll need the instructions from SIS or your dealer. Also when did you last change hydraulic filters? All three I mean, including the full-flow return? That's the expensive one in the aluminium housing. I doubt you have a major engine problem, I also think the smoke is a red herring in this case, as is the mode. Running in heavy all the time will not do damage, but under some circumstances you'll just burn more diesel than you need to. To me this is more likely to be a hydraulic problem, and hopefully not too serious a one at that.
My 320c acted like this even stalling out. We had a fuel issue had to clean the tank out 3 times before it cleared up. Also made it a habit to drain the the tank petcock twice a day for about ten seconds. Have not had a problem in over a year. For a month it was horrible.
The books I've seen call that valve a proportional reducing valve. I don't recall if there is a bypass on that model of machine that enables you to run when the computer is not working properly. If there is it would be in the back of one of the arm rest consoles. If you through the switch and the operation changes you know the problem is engine or computer related. Good Luck!
when checking fuel system dont forget to check the tank breathers not choked up. great site
John C you're right, the valve I'm talking about is called the proportional reducing valve in SIS, and is what controls the powershift pressure. The powershift system is what reduces swashplate angle in response to the ECM signal when engine speed reduces, in effect giving an anti-stall function. I don't think there is a bi-pass, effectively if the powershift system doesn't work you lose your anti-stall function. In the monitor you'll see PS press. which is powershift pressure.
Thanks for all the info, i'll do some checking and get back to you. By the way should i check the same things for My CX210, the CAT was giving too much trouble so i brought the CASE to the site, it behaves in a similar way but can manage more of the heavy digging.
Just thought i should mention, these symptoms occur in automatic mode.
CatD10: Welcome to the Heavy Equipment Forums
Doesn't it sound odd that both your Cat and Case are showing similar symptoms? Did these problems begin recently with both machines? You might want to look at your fuel supply or some other factor common to both machines.
Actually i doubt its a common issue, because one was bought in the US (CAT) and the other in the UK. From the day the 320 landed it was giving trouble, it would not even climb up a small mound of dirt. Like I said, the CASE is doing much better now, may lug a little but nothing significant. The CAT, you can't even raise the boom without trouble. And yes they both use the same fuel supply, filters changed, oil changed. I just found out today though that the turbo was removed recently and the fins weren't spinning freely, the area around the muffler is also very blackened by the smoke. I'm hoping this is not bad.
Well JVS, that probably blows my theory out of the water. If the turbo still isn't spinning there's your trouble. New turbo rqd, make sure you oil the bearing before you fit. If there's soot around the exhaust, chances are whoever removed it didn't refit the exhaust system properly. Make sure oil feed and drain are clear as well.
Be working on it this week, thanks much everyone. I'll give an update when its over.
check the snail isnt binding on the impeller (inlet and exhaust) may be a simple fix, remove snails and clean flanges bolt back together and check.
Funny our 320 did that about 3 years ago operator switched from auto to manual mode and the problem fixed itself and has never come back.
Impeller, snails, not familiar with the terms.
Inside the turbo, the fins
Depending on the year of your machine. I went threw the same problem a few years back and after a dozen calls to the cat sevice department one of the fellas finally thought to mention our machine had a n inline screen that may be stopped up. We tracked it down and from then on when every it acted up a couple of wrenches and a can of spray to clean the screen up and running in 20 minutes. The screen was located in one of the bango fittings on the cab side of the motor ( was fairly agrivating to get to ). It's been a few years but If I recal corectly it was the inlet line to the fule primer maybe? Someone here should be able to give the exact locatin if I am remebering incorctly.
The fuel screen is usually in the banlo fitting on the line coming from the tank going to the fuel transfer pump or lift pump as some say, take out the banjo bolt and look inside there is a small screen that unscrews and will be full of muck! Hope this helps, seen lots of machines with same symtoms and because you have three with same symtoms I would suggest you check for dirty fuel.:canada