RadarTech
Elite Member
I think it is all about the counter balanacing of the crankshaft....
slower the rougher-- makes sense to me...
J
Idle Speed...why so fast??
- Thread starter wowwee
- Start date
- Views: 28675
I think it is all about the counter balanacing of the crankshaft....
slower the rougher-- makes sense to me...
J
leonz
Super Member
Every properly installed three cylinder prime mover I have ever
been around or worked with behaves like this as it was was due
to the engines being bolted to the frame of the vehicle which
had a gas engine and had to be modified to accept this
Duetz Diesel with no rubber isolation mounts),
NO I was not responsible for that mess.
The 3 cylinder Duetz engines in our Ingersoll Rand Air Compressors
did not have these issues because they had the required rubber puck
isolation mounts.
Some machine builders simply bolt the engine to the machines,
which is what I suspect the problem is here due to the description
of the engines behavior at low idle speed. It is much less noticable
at the higher idle due to the engine speed increase.
The Duetz engines use a rubber puck with a drilled hole and steel spacer
to secure the engine mounting feet to the machines engine compartment
allowing the rubber puck to compress only as far as the steel spacer
pressed into the rubber puck used for the shock absorber.
The 3 cylinder Kubota engine is used in a lot of applications.
The Compact Utility Tractor market was simply another avenue
to sell engines and transmissions, which are shipped from
the Kubota home plant world wide, as they sell these engines
for water pumps, generators, miniature rice combines,
rice planters, stationary threshers, small construction machinery
including rollers, tampers, portable screens for gravel and sand
among other uses.
What you are describing completely is an issue of having no
engine isolation from the frame of the tractor.
(They either have a thin piece of conveyor belt between the
mounting foot of the engine and the frame
which simply aids the transmission of engine vibration
or simply nothing at all separating the engine from the tractor frame).
I will post what the engine isolation mount should be/look like
for the 3 cylinder engines when I find it shortly.
My former employers used conveyor belt because they did not want
to buy the pucks for the mounts as they felt they were not required.
All the Saulsbury fire pumps I installed were done this way and they continue
to do it that way.
leon
been around or worked with behaves like this as it was was due
to the engines being bolted to the frame of the vehicle which
had a gas engine and had to be modified to accept this
Duetz Diesel with no rubber isolation mounts),
NO I was not responsible for that mess.
The 3 cylinder Duetz engines in our Ingersoll Rand Air Compressors
did not have these issues because they had the required rubber puck
isolation mounts.
Some machine builders simply bolt the engine to the machines,
which is what I suspect the problem is here due to the description
of the engines behavior at low idle speed. It is much less noticable
at the higher idle due to the engine speed increase.
The Duetz engines use a rubber puck with a drilled hole and steel spacer
to secure the engine mounting feet to the machines engine compartment
allowing the rubber puck to compress only as far as the steel spacer
pressed into the rubber puck used for the shock absorber.
The 3 cylinder Kubota engine is used in a lot of applications.
The Compact Utility Tractor market was simply another avenue
to sell engines and transmissions, which are shipped from
the Kubota home plant world wide, as they sell these engines
for water pumps, generators, miniature rice combines,
rice planters, stationary threshers, small construction machinery
including rollers, tampers, portable screens for gravel and sand
among other uses.
What you are describing completely is an issue of having no
engine isolation from the frame of the tractor.
(They either have a thin piece of conveyor belt between the
mounting foot of the engine and the frame
which simply aids the transmission of engine vibration
or simply nothing at all separating the engine from the tractor frame).
I will post what the engine isolation mount should be/look like
for the 3 cylinder engines when I find it shortly.
My former employers used conveyor belt because they did not want
to buy the pucks for the mounts as they felt they were not required.
All the Saulsbury fire pumps I installed were done this way and they continue
to do it that way.
leon
Last edited:
RadarTech
Elite Member
TheFlatlander
Gold Member
Leon-These tractors have their engines on rubber mounts. That is why there are posts on here about the fans hitting the shrouds when plowing snow.
leonz
Super Member
Boy if they are rubber mounts are that small I would like to see what the mounts look like for sure-its almost as if the there is no steel spacer because these runt engines are mounted in other appliances with no issues.
The low idle should be balanced period just like the high idle; I am curious about the things I mentioned before and I wonder if the injection nozzles are part of the issue with fuel delvery and lack there of?
It worries me only because of aging engine parts and the dreaded piston slap which is of course not a bad as the dreaded dope slap from the Magliatzi brothers from Car Talk.
It again honestly leads me to the unbalanced crank issue/power train, flywheel, torque converter, once again.
Further detective work is indicated with a scope in the crank case to determine if weights are welded to the crankshafts of these engines for balance.
These engines are shipped from Kubota Corporation in Japan to all points on the globe for a lot of other machines and theres a termite in the office paneling someplace.
It would be worth asking neil if he has a crankshaft in his stock parts that they could run through with a dial indicator and metal lathe.
leonz
leonz
Super Member
OK you lost me aceduece sorry-what counter weight?
the only exposed weight you should have is the flywheel pulley which carries the alternator belt and water pump if it is not gear driven.
If the crank pulley is not balanced thats another issue also and would be enough to shake at low idle with or without adequate motor mounts.(which is a no no).
RadarTech
Elite Member
I was thinking about the counter weight on the crankshaft itself the large weights that help the centriful force so when the piston goes up this weights "help" balance out the force of the rotation..
Now, I spent most of my engine work time on small engines and small cars engines... I have NEVER broken down a diesal.. BUT I see no reason why a crankshaft would be that different...
Jed
leonz
Super Member
Both the crank shaft and the flywheel must be balanced with weights if the casting is not machined into balance as the bearing will fail much sooner than normal.
this is no different than balancing tires but operating at a high RPM.:thumbsup:
this is no different than balancing tires but operating at a high RPM.:thumbsup:
RadarTech
Elite Member
maybe I was just thinking of a bad experience..
we had an old sears garden tractor.. dad said sometimes it just "lugged" due to the way the crankshaft was..
Jason