Wetstacking and Idling
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Senior User
Joined: Dec 2003
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From: St. Louis MO
Wetstacking and Idling
I have read many times that these 6.0L are not supposed to be idled for long periods of time but no where have I found what a long period of time is considered. The only time I would idle would be on cold mornings when I start the truck to get the engine and cab warmed up. It is usually done for 5-10 minutes as I would think this would be better then starting up cold and taking off right away. Am I wrong? Is it best to let the truck warm up or just go? What is excessive idling? Is it best when the engine is not warm to let it run for a few minutes even in warm temps?
I read the tech folder and that thing is the bible but it really does not state a true definition of this.
I read the tech folder and that thing is the bible but it really does not state a true definition of this.
Senior User
Joined: Aug 2006
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I have read many times that these 6.0L are not supposed to be idled for long periods of time but no where have I found what a long period of time is considered. The only time I would idle would be on cold mornings when I start the truck to get the engine and cab warmed up. It is usually done for 5-10 minutes as I would think this would be better then starting up cold and taking off right away. Am I wrong? Is it best to let the truck warm up or just go? What is excessive idling? Is it best when the engine is not warm to let it run for a few minutes even in warm temps?
I read the tech folder and that thing is the bible but it really does not state a true definition of this.
I read the tech folder and that thing is the bible but it really does not state a true definition of this.
I have a John Deere tractor and they give a description of wet stacking, and say anything over 5 minutes of idle time the RPM's should be raised to at least 1,200 RPM's or higher to prevent "wet stacking".
Hotshot
Joined: Aug 2006
Posts: 17,398
Likes: 317
From: Whittier, CA
From the 2006 Diesel Supplement manual:
Page 13
them to stick, which in turn, can cause valve train damage.
Page 14
• For extended idle times use an approved idle speed increase device.
Page 12:
******* My comments follow:
Wet stacking is IMO the least of our concerns with the 6.0 WRT idling. Of greater concern is keeping the EGR system clean. Idling, particularly while the motor is cold, does not burn the fuel cleanly. Hang around the exhaust for a while if you doubt it. Also, idling will not warm these motors up, so there is little point in idling in the morning beyond enough to get the fluids moving. We've seen the gunked up EGR valve photos here from those who like to idle.
So, the manual does not give a clear guideline as to how long to idle, except for the turbo cool down paragraph. My advice is, don't idle in the morning to warm it up, because it doesn't work anyway. I give it about 30 seconds, listening for anything unusual and to let the fluids flow a bit, and then I go with a light throttle for the first few minutes.
Page 13
Note:
Idling in cold weather will not heat the engine to its normal
operating temperature. Long periods of idling in cold weather can cause
a buildup of heavy deposits of carbon and rust on valve stems causing
operating temperature. Long periods of idling in cold weather can cause
a buildup of heavy deposits of carbon and rust on valve stems causing
them to stick, which in turn, can cause valve train damage.
Page 14
The following cold weather idling guidelines must be followed:
•
Avoid idling the engine for more than 10 minutes at a time.
•
Use Motor Craft Cetane Index improvers of a non-alcohol based from a
reputable manufacturer.
reputable manufacturer.
•
Maintain the engine cooling system properly.
•
Do not shut the engine down after an extensive idling period (10
minutes or more). Drive the vehicle for several miles with the engine
at normal operating temperatures under a moderate load to burn off
any accumulated carbon and varnish.
minutes or more). Drive the vehicle for several miles with the engine
at normal operating temperatures under a moderate load to burn off
any accumulated carbon and varnish.
•
Consider using an engine block heater.
• For extended idle times use an approved idle speed increase device.
Idle control:
For periods of extended idle, the throttle should be set at an rpm, which
is sufficient to keep the engine at normal operating temperatures. This
action can reduce the amount of engine damaging deposits.is sufficient to keep the engine at normal operating temperatures. This
Page 12:
STOPPING THE ENGINE
Turn the ignition to 3 (OFF). To prolong engine life (after extended high
speed or maximum GVW operation), it is recommended that a hot engine
be allowed to operate at low idle for about 7–10 minutes which would
allow sufficient time for the turbocharged engine to cool down.speed or maximum GVW operation), it is recommended that a hot engine
be allowed to operate at low idle for about 7–10 minutes which would
******* My comments follow:
Wet stacking is IMO the least of our concerns with the 6.0 WRT idling. Of greater concern is keeping the EGR system clean. Idling, particularly while the motor is cold, does not burn the fuel cleanly. Hang around the exhaust for a while if you doubt it. Also, idling will not warm these motors up, so there is little point in idling in the morning beyond enough to get the fluids moving. We've seen the gunked up EGR valve photos here from those who like to idle.
So, the manual does not give a clear guideline as to how long to idle, except for the turbo cool down paragraph. My advice is, don't idle in the morning to warm it up, because it doesn't work anyway. I give it about 30 seconds, listening for anything unusual and to let the fluids flow a bit, and then I go with a light throttle for the first few minutes.
Thread Starter
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Senior User
Joined: Dec 2003
Posts: 261
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From: St. Louis MO
Thanks for the info. That is really what I was looking for. I bought the truck and it did not have a manual with it so I ahve a few more days before the dealer gets me one in the mail. That is the main reason for all the questions.
Senior User
Joined: Feb 2008
Posts: 235
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From: Albany, OR
bpounds I wonder if those suggestions pertain to cooling down the turbo also? I used to let my truck sit for a good 5-10 mins after I towed anything. Now I just drive carefully my last 5-10 miles and let it cool down naturally (I've been told this method works fine) Any Neh sayers?
Hotshot
Joined: Jul 2005
Posts: 13,834
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From: Middle Tn.
If I am pulling off the freeway, by the time I find a place to park it has usually cooled down enough. I usually feel safe after 3 to 4 minutes and have never had a problem.
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Posting Guru
Joined: Dec 2006
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From: Kansas City/Breckenridge
IMO 7-10 minutes is way to long. If I remember correctly wet stacking occurs at 278 degree EGT. Given I have a wide open exhaust but after a tops of 1-2 minutes after hard towing I am below 350 degree's and 400 is considered safe. There are a lot of factors to add to that though. Stock exhaust, AC on, ETC.
I don't think wet stacking is a real issue with warm up since from what I understand for a engine to start "wet stacking" the engine temperature needs to fall below normal operating tempeture after being warmed up. It is more worrying about the EGR system and everything else clogging up. Given the truck automatically rev's up in cold tempetures this isn't really an issue either. I would say 5-10 minutes is fine in the morning.
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Hotshot
Joined: Aug 2006
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From: Whittier, CA
I usually figure, by the time I pull off the interstate, around the ramp, get to a fuel pump, campsite, whatever, the turbo has cooled sufficiently. I don't worry about idling beyond that to cool off. But if I am towing, and pull off onto the shoulder real quick, I do give it a minute to cool down. That has worked for me thus far.
Senior User
Joined: Mar 2008
Posts: 195
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From: Hendersonville, NC
One time on a cold night for here like 5 * i went to crakn up my truck after work to let it warm up for me. When i tunred on the key my edge insight said the block and oil where 10* it cranked I turned on the heat as i walked away i herd the atomatio elivated ideal turn on.. I walked in and out a few times taking stuff to the truck went to punch out and wound up talking to the boss man for what had to have ben atlest 30 min forgot about my truck being on.. Get back out to the truck idle has gone back to normal and the edge insight says the coolent temp is 185 which is what it is when i drive around. and the cab is so hot you could grow orcids in there. I dont make it a habet buy any meens , i ueualy just give it about 5 to 10 min on cold nights like that..
But if you got your EGR blocked off you have no risk of gumming up th egr system right ?
Fleet Owner
Joined: Nov 2003
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This is from a Tech who used to be active on the site. His limit is 10 minutes on the idle (I tend to be much more conservative). The recent PCM strategies have an elevated idle strategy, but when idling more than ten minutes (I use 5 minutes as the limit), it is not sufficient. You need the "high idle mod"! If temperatures are much below freezing, you will need even higher idle speed that 1200 rpm for any extensive idling. The problems from extended idling can go beyond the EGR system, so it is still wise to minimize idling as defined below!
Wet Stacking is basically un-burned fuel and partially burned fuel that builds up on the exhaust valves, turbo and exhaust system. It can cause the exhaust valves to stick open (due to sludge build up on the valve stem) leading to a bent valve. It can cause problems with the VGT vanes sticking. Unlike a gas engine, our diesel engine gets cooler when it idles at low rpm, and when the EGT temps fall below 275F wet stacking occurs. At temperatures down to freezing running at 1200 RPM generally causes EGT to be above 275F and wet stacking is prevented. In extremely cold conditions the idle speed will need to be higher.
Also extended idling of our diesel engine with an EGR system causes excessive soot loads in the engine and engine oil, so more frequent oil & filter changes are recommended for excessive idling.
Any time you idle for more than 10-minutes (less in below freezing temps) high idle strategy should be employed.
The 6.0 has a "Cold Engine" strategy which is invoked by the PCM when the EOT is below 158F (generally when the engine is first started). Once the EOT reaches 158F the "Cold Engine" strategy is turned off by the PCM and the idle slows back to normal. The EOT can be at 158F or higher, but the combustion temps are still cool and the EGT is below 275F leading to wet stacking from extended idling. The "Cold Engine" strategy will not prevent wet stacking from occuring due to extended idling times (longer than 10-minutes).
Also, unburnt fuel "washes down" the cylinder walls, removing lube oil and bringing the potential to incur fairly significant damage to the cylinder walls as time goes by. In a V-configuration engine (the PSD, in this case) piston isn't moving vertically, so it can't support the fuel. Gravity will pull it to the lower cylinder wall, and there's where the problem starts.
I agree with Bill (bpounds) - I idle for 30 seconds to a minute on a cold start and then take it easy on accelerations until things appear to be warmed up (at least 5 minutes). Remember, the coolant temps will be the first to rise, the oil temps and the engine "heat soak" take longer.
Wet Stacking is basically un-burned fuel and partially burned fuel that builds up on the exhaust valves, turbo and exhaust system. It can cause the exhaust valves to stick open (due to sludge build up on the valve stem) leading to a bent valve. It can cause problems with the VGT vanes sticking. Unlike a gas engine, our diesel engine gets cooler when it idles at low rpm, and when the EGT temps fall below 275F wet stacking occurs. At temperatures down to freezing running at 1200 RPM generally causes EGT to be above 275F and wet stacking is prevented. In extremely cold conditions the idle speed will need to be higher.
Also extended idling of our diesel engine with an EGR system causes excessive soot loads in the engine and engine oil, so more frequent oil & filter changes are recommended for excessive idling.
Any time you idle for more than 10-minutes (less in below freezing temps) high idle strategy should be employed.
The 6.0 has a "Cold Engine" strategy which is invoked by the PCM when the EOT is below 158F (generally when the engine is first started). Once the EOT reaches 158F the "Cold Engine" strategy is turned off by the PCM and the idle slows back to normal. The EOT can be at 158F or higher, but the combustion temps are still cool and the EGT is below 275F leading to wet stacking from extended idling. The "Cold Engine" strategy will not prevent wet stacking from occuring due to extended idling times (longer than 10-minutes).
Also, unburnt fuel "washes down" the cylinder walls, removing lube oil and bringing the potential to incur fairly significant damage to the cylinder walls as time goes by. In a V-configuration engine (the PSD, in this case) piston isn't moving vertically, so it can't support the fuel. Gravity will pull it to the lower cylinder wall, and there's where the problem starts.
I agree with Bill (bpounds) - I idle for 30 seconds to a minute on a cold start and then take it easy on accelerations until things appear to be warmed up (at least 5 minutes). Remember, the coolant temps will be the first to rise, the oil temps and the engine "heat soak" take longer.
Cargo Master
Joined: Dec 2007
Posts: 2,196
Likes: 120
From: Carstairs Alberta
between my 2 trucks i've put on over 100,000 miles. my warmup is about like bismic and bpounds suggest i have yet to anything more than egr, and sensors. my 03 ate injectors but that was half my fault and no connection to warmup. just accelerate lightly and smoothly.i try to stay under 1500 for the first 2-3 blocks then work up to 2000. living in the great white north its alot colder than n carolina. -40f isn't terribly unusual i plug in overnight crank it up and go about like summer, if i need to scrape windows i'll leave it idle. driving it immediatley will warm it up faster and as a result it will run more efficiently sooner
Hotshot
Joined: Aug 2006
Posts: 17,398
Likes: 317
From: Whittier, CA
Can you please explane how it "dose not work"
One time on a cold night for here like 5 * i went to crakn up my truck after work to let it warm up for me. When i tunred on the key my edge insight said the block and oil where 10* it cranked I turned on the heat as i walked away i herd the atomatio elivated ideal turn on.. I walked in and out a few times taking stuff to the truck went to punch out and wound up talking to the boss man for what had to have ben atlest 30 min forgot about my truck being on.. Get back out to the truck idle has gone back to normal and the edge insight says the coolent temp is 185 which is what it is when i drive around. and the cab is so hot you could grow orcids in there. I dont make it a habet buy any meens , i ueualy just give it about 5 to 10 min on cold nights like that..
But if you got your EGR blocked off you have no risk of gumming up th egr system right ?
One time on a cold night for here like 5 * i went to crakn up my truck after work to let it warm up for me. When i tunred on the key my edge insight said the block and oil where 10* it cranked I turned on the heat as i walked away i herd the atomatio elivated ideal turn on.. I walked in and out a few times taking stuff to the truck went to punch out and wound up talking to the boss man for what had to have ben atlest 30 min forgot about my truck being on.. Get back out to the truck idle has gone back to normal and the edge insight says the coolent temp is 185 which is what it is when i drive around. and the cab is so hot you could grow orcids in there. I dont make it a habet buy any meens , i ueualy just give it about 5 to 10 min on cold nights like that..
But if you got your EGR blocked off you have no risk of gumming up th egr system right ?
What I mean is, your engine won't build the temps that result in efficient fuel burn from just idling. Obviously it will get warm enough to open the coolant thermostat, which is what you saw at 185°. That is enough to warm the cab, so if that is your goal then yes it does work, but at the expense of your motor.
Blocking the EGR is good because it is the Achilles heel, but you still risk carbon buildup in the remaining passages.
I'm certainly no expert, but this is my understanding and is why I avoid idling.
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