IDI Math Challenge
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Postmaster
Joined: Mar 2013
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From: Over There
IDI Math Challenge
Just for kicks.
Your challenge should you choose to accept it is to figure out how long before letting it idle uses more fuel then starting it again.
So as I figure IDIs use very little fuel idling but use a lot of electricity to get started again(glow plugs and starter) That juice is alternator drag to charge the batteries again which uses more fuel.
Your challenge should you choose to accept it is to figure out how long before letting it idle uses more fuel then starting it again.
So as I figure IDIs use very little fuel idling but use a lot of electricity to get started again(glow plugs and starter) That juice is alternator drag to charge the batteries again which uses more fuel.
Cargo Master
Joined: Oct 2012
Posts: 3,072
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From: California
here's a link... Idling Your Car
But I don't know if I believe it. It sounds like a bunch of uneducated bureaucrats saying what they want to believe. I'd prefer if Mythbusters tested this and I got to see their results.
But I don't know if I believe it. It sounds like a bunch of uneducated bureaucrats saying what they want to believe. I'd prefer if Mythbusters tested this and I got to see their results.
Post Fiend
Joined: Feb 2009
Posts: 8,005
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From: Ottawa, Ontario
I've read a long time ago on here someone had answer this, that a properly tuned IDI, idling with a standard tranny, with no load on it, will use about 1 gallon of fuel every 2 - 2 and a half hours.
This is something I would find interesting trying out.
This is something I would find interesting trying out.
Post Fiend
Joined: Mar 2009
Posts: 6,243
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From: Chicago and Mt Carroll IL
My 5 gallons in 8 hours was pretty close to that WITH a load (pto) and high idle, which also helps to prevent wet stacking.
Post Fiend
Joined: Feb 2009
Posts: 8,005
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From: Ottawa, Ontario
A high idle switch would be best if extended idle is done often, to exactly prevent what you just said, wet stacking.
IIRC, that gallon every 2 hours or so was on high idle as well.
With that being said, I've always left my van idling at gas stations while fueling it up, or even stoping in somewhere I know i'll come right back out, always leave it running. It puts more wear on things like the starting system (starter, batteries) and glow plugs for people who don't have manual plugs than anything.
IIRC, that gallon every 2 hours or so was on high idle as well.
With that being said, I've always left my van idling at gas stations while fueling it up, or even stoping in somewhere I know i'll come right back out, always leave it running. It puts more wear on things like the starting system (starter, batteries) and glow plugs for people who don't have manual plugs than anything.
Lead Driver
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Post Fiend
Joined: Feb 2009
Posts: 8,005
Likes: 7
From: Ottawa, Ontario
Wet stacking is/happens after extended periods of idling in any diesel, EGT's get to LOW, and fuel doesn't get fully burnt, and it runs out the exhaust pipe in liquid form, mixed in with the natural soot in the exhaust pipes, it makes it look oily, and it can look like oil is dripping from your exhaust. That's why it's important when you idle for long periods, once in a while, put a good load on it, or give 'er a couple revs. And make sure you idle speed is 1000-1200 range to prevent "Wet stacking"
I think the term wet "stacking" is from the trucking world, as when it happens to them, their stacks get wet, so they called it wet stacking.
I think the term wet "stacking" is from the trucking world, as when it happens to them, their stacks get wet, so they called it wet stacking.
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Postmaster
Joined: Dec 2004
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From: Maple Valley, WA
LMS is right on the money...
The IDI uses right about 14mm^3/stroke at idle...
That equates to right about .58gph@800RPM.... Or 4.64 gallons over 8 hours...
5 gallons is right on the money for a high idle...
Running the truck for more than a couple minutes is a waste of fuel... But "waste" is all up to interpretation, I idle my truck because I like a warmed up truck at all times, just the way it is...
The IDI uses right about 14mm^3/stroke at idle...
That equates to right about .58gph@800RPM.... Or 4.64 gallons over 8 hours...
5 gallons is right on the money for a high idle...
Running the truck for more than a couple minutes is a waste of fuel... But "waste" is all up to interpretation, I idle my truck because I like a warmed up truck at all times, just the way it is...
Junior User
Joined: Apr 2012
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I like a warmed up rig too and don't mind letting it idle for a bit, but am not afraid to shut it down at the pump or just to talk to someone - these old IDI's are a bit on the loud side afterall!
I believe wet stacking refers to what John is talking about - low EGT's and unburnt diesel, but the problem isn't so much unburnt fuel dripping from the pipe as it is unburnt fuel staying in the cylinder and washing the oil away from the rings. Lots of engine idle time can lead to premature wear.
I believe wet stacking refers to what John is talking about - low EGT's and unburnt diesel, but the problem isn't so much unburnt fuel dripping from the pipe as it is unburnt fuel staying in the cylinder and washing the oil away from the rings. Lots of engine idle time can lead to premature wear.
More Turbo
Joined: Nov 2010
Posts: 521
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From: Cincinnati, OH
Kind of related, and this is my opinion. If you have a turbo engine, letting it run instead of constant shutting off and restarting is probably better for the turbo bearings and keeping them from heat soak and oil coking.
Also good to let the engine idle down for about 30 seconds before shutting it off so the turbo can spool down and let the oil flow help remove heat.
Also good to let the engine idle down for about 30 seconds before shutting it off so the turbo can spool down and let the oil flow help remove heat.
Lead Driver
Joined: Oct 2003
Posts: 8,476
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From: Madison, WI
I almost always shut down when stepping out of the cab. Don't trust the parking brake by itself to keep the truck from creeping away (the '85 doesn't even have a parking brake, actually....).
Post Fiend
Joined: Feb 2009
Posts: 8,005
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From: Ottawa, Ontario
^^ man it bugs the hell out of my that the park brake is seized in my automatic van, I have no idea how you go on without a park brake in a standard truck! That be the very first thing I fix on a standard truck if it needed repair.
Lead Driver
Joined: Oct 2003
Posts: 8,476
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From: Madison, WI
Got the parts. Only recently realized that this rear axle requires you to pull the hub apart to pull the drum. Only a gravel driveway to work on. Thinkin' I'll pay a shop to do the rear cables, then hook the rest up myself....