i have read around here about wet stacking, i wanted to know what this is and how it damages the 7.3 in my ford f250.

 

I had this discussion with my brother last year, he owned a class A RV with a Cummins diesel. From my recollection, "wet stacking" is the occurance of unburnt diesel fuel that accumulates in the cylinders after prolonged engine idling at low RPM's. This discussion followed the debate on wether or not it was harmful to let your diesel idle for prolonged periods of time. I've noticed that on my truck, when it was cold outside, the engine would automatically idle up and increase RPM's after a period of time when I would start it up in the mornings. I believe this feature is designed to prevent wet stacking as it keeps the engine from running to long at low RPM's before it has warmed up enough. I think big rigs utilize this concept as well, in fact I seem to remember hearing about "auxiliary idling devices" installed on their diesels to vary the RPM's and prevent wet stacking while they sit running for extended periods. If anyone knows any more on this subject, please correct me if I'm wrong!

 

Your right on. To be a little more specific... the unburnt fuel will build up on the valve stems. And can cause a valve to stick open and contact the piston. Bad................jskufan well said!

 

Not something that should even concern you unless you spend a lot of time at low idle in below freezing ambient conditions.

 

usually on cold days, we start our '95 PSD up and let it idle for 3-5 minutes, and then take off down the road. accelerating through gears 2-4, it blows alot of blue smoke. is this related to "wet stacking"? i thought it was "building up"

 

Letting it warm up for a few minutes when it's cold is good for it, gotta get the oil warmed up and circulating the engine before you run it hard. The blue smoke is just oil getting by the rings and seals, not everything is warmed up and sealed tightly, so oil is able to seep by.

 

wow guys thanks for the great replies guys !!

 

I thought the "wet stacking" issue was the ring seals not being tight enough when not all the way to operating temps and burning excesive oil. Our PSD idle all day long sitting at the race track and some have close to 300,000 miles on them. I don't think "wet stacking" is a serious concern with the PSD.

 

Key note is OUTSIDE temperature, I have heard lots about wet stacking but have not ever heard of an incident where a problem has been a result of it.

 

I was under the impression that wet stacking could happen in any weather environment if you idle low for long periods? Am I thinking correctly?

 

good question medic.


can anyone answer this one?

 

It is more of a concern during winter/colder months because the air temperature is colder, so when it is sitting there idling the engine is surrounded and drawing in cooler air than in summer months making it run cooler, so to speak. I don't think it is a problem that PSD owners have to worry about, but it's always good to know about it, what it is and how to prevent it.

 

I've heard many big rigs idle at rest stops. The idle doesn't sound any higher than stock. This was during the summer however. I've never heard them in real cold weather. But I know they run radiator blockers in cool weather to heat up their engines, and increase their EGTs. AIC may be necessary if your EGTs are less than 275 during idling. We already got AIH and the EBPV to increase the EGTs during cold weather idling. If you removed both of these there should be a concern for wetstacking and oil dilution during idling in cold weather especially if your EGTs are less than 275.

 

hey guys i own a 2001 kenworth w900L 550 cat i live in mass and run local my truck runs all night at deliverys only during winter months never had a wet stacking problem my idle never changes at deliverys or at cold startups

 

Here's a short article about wet stacking that was published on Dieselmanns web page. http://www.intellidog.com/dieselmann/b_smoke9.htm