What speed is "high idle?"

Mike,

For the BX, 1400 rpm is slow Idle and is normal. For us BX owners, fast idle means just crack the throttle open some so the engine is not running at its slowest speed.

Big trucks have a fast idle button that they push/pull to make the engine idle faster. That's where the "fast idle" term came from.

Idling a diesel for a long time is bad for it in theory. So its better to run it at fast idle than slow idle. I'm not sure all the exact reasons slow idle is bad, but I think its a combination of multiple things. The engine doesn't run smooth at slow idle, the fuel mix firing in the cylinder when the piston is moving slow puts more stress on the crank, and piston connecting rod, there's more carbon build up because its not running hot enough to burn clean.

So I never let it run at 1400. Only when shutting down, I throttle all the way down then shut off. On start-up I let it warm up at 1600. When I'm working and need to stop working to get off the tractor to do something, I let it run at 1500-1600, for few minutes. If I need to take a longer break, I shut it off.

The little diesels in our BXs have a tendency to rattle our dentures if we push the throttle lever all the way forward. "High Idle" in my opinion is that point as you rev it up at which the engine noticeably smooths out. For mine it's 1600-1800 RPMs. I preset mine to this position before shutting down in the cold weather so that it'll fire up and warm up more smoothly.

JRC0528 said:

The little diesels in our BXs have a tendency to rattle our dentures if we push the throttle lever all the way forward. "High Idle" in my opinion is that point as you rev it up at which the engine noticeably smooths out. For mine it's 1600-1800 RPMs. I preset mine to this position before shutting down in the cold weather so that it'll fire up and warm up more smoothly.

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Thanks. mfarmelo suggested the same 1600 RPM, so I'll try that myself.

JRC0528 said:

The little diesels in our BXs have a tendency to rattle our dentures if we push the throttle lever all the way forward. "High Idle" in my opinion is that point as you rev it up at which the engine noticeably smooths out. For mine it's 1600-1800 RPMs. I preset mine to this position before shutting down in the cold weather so that it'll fire up and warm up more smoothly.

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I've been trying 1600-1700 RPM, and the engine definitely runs smoother at that speed.

So, is there a mechanical stop on the throttle lever that I can adjust to set a fast idle speed when the lever is pushed all the way up? I don't like having to bump it up and down to get 1600-1700 every time I want to idle when dismounting or shutting down.

JD-Jeff said:

When I took my BX in for it's 50 hour service the idle RPM was 14-ish. I asked if they would set the idle speed at 1600. These little diesels smooth out a bunch at 1600 RPM.

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Did you see how they did it? Seems to me there should be an adjustment screw, but I'm hoping for some information before I start poking around behind the dash, and possibly mess up something.

Mike Dodd said:

Did you see how they did it? Seems to me there should be an adjustment screw, but I'm hoping for some information before I start poking around behind the dash, and possibly mess up something.

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I don't have a clue how they did it. I left it for the day and picked it up on the way from work that afternoon.

If I get the time to stop by the dealership this week I'll find out and let you know.