can someone please explain what this is? i read about it is the fuel getting into the heads or something like that, but reason for asking is i heard that is why its not good to let this diesel idle for a long time, hell, isn't that what a diesel is for? my understanding of diesels that it was better to let them idle instead of shutting them down for short periods of time, and i read on some thread about a guy with his 7.3 blowing the #5 rod out while in traffic and ford saying it was his fault, wetstacking, he had 26,000 miles on the truck, i don't want the same to happen to me!

 

Wetstacking is from idling, unburnt fuel lines the cylinder wall and waters down the oil film causing premature ring wear. Also, fuel ends up watering down the oil and eventually bearing damage. To prevent, use high idle mod, don't idle, use a controller. Even big diesels are not meant to idle, they might run at 1200 rpm but this is ok. Good lubrication, good fuel burning. Even big diesels, best to use Webasto, block heaters, oil heaters, rather than to long idling. Diesels shake apart and start to leak more this way too....

 

yea i always though the same thing..im surprised but i quess exess idle on any vechile isnt good.

 

Wet stacking has more to do with the engine temp not being high enough at idle. Increased idle, more load, etc. all increase the temp and help to prevent wet stacking. That said, exhaust brakes will help to do the same thing. This is what OTR diesels use and what makes them able to idle all night while the driver sleeps. You can use these on smaller diesels as well. Check out some of the sponsors who sell these.

 

hanks for the info everyone, now for a follow-on question, i just read a thread about the fast idle mod, will this be sufficent to not cause wet stacking? i don't need to idle long times very often but when i do, i don't want to risk damage, also, my truck 04f250 starts idling high by itself sometimes, is this an auto high idle feature to prevent wet stacking? therefore i don't need the high idle mod?

 

I own a 7.3L Turbo Diesel and I know that my 7.3 has a high idler in it. Basically, when I'm out of the truck, or in Park after about 10 minutes the truck starts to idle at 1,100 RPM, up from the slower 600RPM. This keeps the engine hotter and prevents it. I have never heard of a Stroker blowing because of this. I know that Cummins had some serious problems with this.... to the best of my knowledge they've fixed this. But yeah.... it could happen, the unburnt fuel sticks to the valves and the piston smashes them.

DC-9-32

 

For your follow-up question, my understanding is that there is a cold temperature automatic high idle function....but if you wanted to idle the truck for an extended time after the engine was warmed up (during the summer for example) you would need to add the high idle mod....very simple mod and works great with aux switch

 

Scafes, the exhaust brake does nothing for increasing temps during idling, it is for holding the truck back instead of using regular brakes under load. 6.0 Exhaust brakes are not recomended because of the Variable Vane Turbo. Big trucks ussually use Jake break which is in the head not the exhaust, it uses exhaust compression in the cylinder, not the exhaust system. All big trucks use high idle controllingto prevent wet stacking. Often to run PTO, hydrolic accessories ect.

Yes, the unburnt fuel is due to low temperatures, causing oil dilution, wet cylinder. At idle not enough heat is generated.

 

What Kind of time are we talking here, 20 min or 1 hr or more. For Idling

 

i maybe would idle it 10-30 minutes if and when i did, just to stay warm. then would shut it off for awhile until it got too cold again.

 

The idea is to not let the cylinder temps get too low. It would be better to shut it off to begin with or go out and rev it 1200 or so to warm up the cylinders. My 7.3 has auto idle and backpressure valve to heat cylinders for good combustion. Don't have egt so I don't know if it makes a difference in actual use in cold weather. Anybody ever look at egt's during extended cold weather idle?

 

wetstacking has more to do with unburnt fuel coating the exhast system and valves. I work on indusrial generators and have seen the effects of wetstacking first hand. As long as you can get the exh temps high enough after idleling you should be fine. I have put old generators under full load to find chunks of years of unburnt fuel being forced out of the muffler. Looks like chunks of hardened tar. Have also seen exh fires from it too.

 

i got this from kubuta's website

Q. What does the term "Wet Stacking" mean in a diesel engine?
A. Diesel engines are designed to operate with a load. When a diesel engine operates considerably below the rated output level the engine can start to over-fuel or "Wet Stack". Diesel engines perform most efficiently in the 70-80% range of rated output. When an engine operates for a prolonged period of time below 40% of the rated output it begins to over-fuel. This occurs because the injection tips began to carbonize and disrupt the fuel spray pattern. In commercial generator standby/emergency systems where loads can vary and low output conditions can occur more frequently because of the diverse load applications, an automatic load bank is normally used. A load bank will place a "false" load on the generator system to keep the diesel engine properly loaded to prevent a "Wet Stack" condition. In residential or small business applications a "false" anti-wet stack load condition can be accomplished with the use of an electric heater or other high load appliance to make sure the diesel engine generator system is not allowed to operate for prolonged periods of time below an acceptable level. Once a diesel engine begins to "wet stack" the only way to correct the problem is to load the engine for a couple of hours to burn off the excess fuel and clean up the engine. Some diesel engines are less prone to "wet stacking" than others. Generally, electronically controlled engines and engines with advanced emission systems are less likely to "wet stack". Unfortunately, all diesel engines will "wet stack" if operated for long periods of time considerably below the rated output level. It is for this reason that proper sizing and design is important. ADG can help you with all your sizing and design considerations. It is part of our Sales Engineering Service program and it is free.





i would wire up the high idle switch if you plan to idle at all.

 

For 5 or 10 minute idle time, I wouldn't worry much so long as when you drive its for atleast a half hour or so. If you are idling longer than that, use the high idle mod. Especially if warming up in cold weather or warming up to run A/C longer than 20 minutes. The other thing you might want is a remote start. I have an astrostart, which can be set for restarting by temp, only runs 36 minutes then shuts down. It can also be set to restart when the block cools down.

I don't have a pyrometer on mine, but to give you an idea, the pyro on our tractors would barely move up off the bottom at idle in cold weather.

 

good post ford 390, Yes a load bank is used on generators to bring them to full load, We usually run them under full load for 4 hours straight. Unfortunatly, a load bank is an option not every generator has. it is more uncommon to see a gen with a built in load bank, and the majoroty of customers choose not to load bank there generators. This also over the years causes the generator performance to drop off due to the wet stacking conditions. As I have said before, if you idle for a long period of time, run the engine hard for a while and get the exh temps up to burn the krap out of the exh. I have let my 6.0 idle for 2-3 hours at a time, But I am in it all the time so it gets a work out too.