2007 Cat 303C CR Engine is the Mitsubishi S3Q2-E1 3 cyl. This is the only mini excavator that I have driven, and my issue is first that I think that i shakes and rattles quite a lot at idle and low RPM. It rattles so much so that I have to drive at a pretty high RPM, but then the hydraulics gets too sensitive and quick in its movements, so I can seem to get any flow in my digging. If you look at the video clip you can see the rattle, and you can also hear my other issue. Is the high pitch metal rattle that sounds like a loose washer or something like that. I cant find anything thats loose or anything! The engine mounts looks fine to me, so I dont really think that they are my problem, but I can not guarantee that. Does this engine have three or four engine mounts? I have only found three... Check pics and video and please give my a hint on where to start searching for my problems!
http://youtu.be/2y7lXzqOgJ8 Here is the video!
Our 2003 Cat 303 does the same thing at low idle, I just always assumed thats how it was normally? :beatsme
Well My 303 rattle so much that the windows shakes and makes noises. I mean, it does seem to run fine in the higher revs and i feels powerful to me. But I feel that I should have bought a 4 cyl instead. :-(
It's a piece of construction equipment, not a limousine. Perhaps my perspective is distorted by years of riding a Harley-Davidson, but your video does not strike me as unusually rough. My 303C CR is a bit rough at idle, but smooths out above idle and especially with a load on it. The Yanmar in my John Deere is also rough at idle. I notice that the Cat has a good bit of insulation between the engine and operator station. Now one difference between your machine and mine is that mine is open station, not enclosed cab. I wonder if the enclosed cab has more stuff to rattle in response to the engine, and the cab holds the sound in.
my yanmar 3 cyl. is rougher than a cob at idle, nice and smooth as soon as It hits 1500 rpm or so. I think its normal for 3 cyl. to idle rough
I have a Cat 302.5 with the Perkins engine. At idle it purrs like a kitten. I would agree that at higher RPMs the contols are very sensitive without any load on them.
your harmonic balancer may be off sync
It's normal for the 3 cylinder Perkins.....very normal and talked about concern. As long as it turns silky smooth at about 1500 RPM's there is NO issue...
Yeah, it's just the mechanical nature of a 3 cylinder diesel at idle.
I have 3 different pieces with yanmar 3 cylinders and all of them rattle at idle. The oldest one is very sensitive to air in the fuel. When the injection pump loses prime it looks and sounds like it will rattle the mower to bits, but it's survived 20+ years. They all smooth out even a few hundred rpm above idle.
Well mine has a Mitsubishi engine, so I dont know if it aply to mine aswell? I dont have an RPM gauge either, so I dont know at what rev it smoothens out. All I know is that it gets really smooth up in revs, but I think that the hydraulichs feel a bit to sensitive for my taste when revving this high. It sure would be sweet to be able to turn down the revs a bit and get the digging more smooth, but the excavator rattles too much for that now.
Engine make really isn't important. As the manufacturers go more towards light weight and fuel economy , a technical issue and little studied science of torsional vibration and resonance appears. This becomes more apparent with the small , light weight three cylinder design. From an engineering prospective, the three cylinders rotating on the same crank without allot of mass to absorb vibration it leads to this vibration or resonance you are seeing. Again , this harmonic has been widely talked about and addressed by the manufacturers. The older machines display this issue allot more than current designed three cylinders. It's technically not an issue, nor does it effect long term reliability and generally clears up after a few hundred RPM's are added. It's more of an operator comfort issue just like you are describing....if the machine has been left to idle allot, the motor mounts can become degraded and cause more vibration . You could try replacing those motor mounts and various isolators and it may help a bit...Other than that there really isn't much wrong or that can be done to resolve it. It a well Engineered deign flaw in certain older machines that has long been addressed by all major equipment manufacturers...