mrdonut12
05-21-2005, 11:47
There are far too many coach advertisements with this listed as
a positive selling point.
The engines in these things are designed to go a lot of
miles and there's no reason for this many failures.
One simple thing we can all do is the simple cool down
after coming off the highway.
The turbo charger is a turbine that has 2 sides and a
bearing in the middle. The force of the exhaust drives one side
and the other side forces more air into the engine. The more
exhaust force, the more air is forced into the engine and the
more power developed.
The bearing in the middle isn't a bearing like we think of
one, with little rollers in it. It's a ring of very soft metal
that's smooth. The shaft of the turbine is very hard metal and
also very smooth. Pressurized oil forced into the gap between the
2 produces a very slick environment and the shaft spins very
freely with very little friction.
When a very hard metal rubs against a very soft metal with
a film of oil in between, very little wear occurs. If both were
very hard, wear would be greater.
The hot exhaust really heats up the turbine and when you come
off the highway and shut off the engine, the oil flow stops and the
oil gets cooked in the turbo bearing.
When restarted, the oil is gone and severe wear can occur until
oil pressure and flow is restored. Little bits of bearing debris
are now floating through your oil and engine.
So, to protect your engine coming off the highway, cool the
engine by downshifting and letting the engine slow you down. Take your
time on decel, you're sucking cool air into the engine and cooling off
the turbo.
If you have a digital pyrometer, you can take the turbo's
temperature to see how long of a cool-off cycle it really needs.
Even in a non-turbo (or your generator), let the engine run after
the load is removed to allow the exhaust valves and parts of the
cylinder cool off so you don't bake something.
Giving engines a cool down cycle can avoid serious premature
engine wear and help them live forever. It's something you need to know.
George Witt
81 FC 35
Lincoln, Nebraska--Huskers
a positive selling point.
The engines in these things are designed to go a lot of
miles and there's no reason for this many failures.
One simple thing we can all do is the simple cool down
after coming off the highway.
The turbo charger is a turbine that has 2 sides and a
bearing in the middle. The force of the exhaust drives one side
and the other side forces more air into the engine. The more
exhaust force, the more air is forced into the engine and the
more power developed.
The bearing in the middle isn't a bearing like we think of
one, with little rollers in it. It's a ring of very soft metal
that's smooth. The shaft of the turbine is very hard metal and
also very smooth. Pressurized oil forced into the gap between the
2 produces a very slick environment and the shaft spins very
freely with very little friction.
When a very hard metal rubs against a very soft metal with
a film of oil in between, very little wear occurs. If both were
very hard, wear would be greater.
The hot exhaust really heats up the turbine and when you come
off the highway and shut off the engine, the oil flow stops and the
oil gets cooked in the turbo bearing.
When restarted, the oil is gone and severe wear can occur until
oil pressure and flow is restored. Little bits of bearing debris
are now floating through your oil and engine.
So, to protect your engine coming off the highway, cool the
engine by downshifting and letting the engine slow you down. Take your
time on decel, you're sucking cool air into the engine and cooling off
the turbo.
If you have a digital pyrometer, you can take the turbo's
temperature to see how long of a cool-off cycle it really needs.
Even in a non-turbo (or your generator), let the engine run after
the load is removed to allow the exhaust valves and parts of the
cylinder cool off so you don't bake something.
Giving engines a cool down cycle can avoid serious premature
engine wear and help them live forever. It's something you need to know.
George Witt
81 FC 35
Lincoln, Nebraska--Huskers