This is odd…..I remember a few years back a discussion of that very same topic with regulars on this forum…….. so I go to Advanced Search and nothing🧐 no matter what keys words I use

Anyway, IIRC I don’t think anyone could say that they had personally seen evidence of it on the 7.3 but it was mentioned if idling for “long” periods of time - a high idle tune would prevent any wet stacking…..at least that’s what I remember 🤷‍♂️

 

I've read all kinds of things from just increasing the idle speed up above 1200-1500 RPS's to prevent it to where you need to get the exhaust temperature up to around 500 degrees to prevent it.

I avoid it by not idling any longer than needed

 

I recall that the point where wet stacking might occur was below 300F, which agrees with the 275F you mentioned.

Also, below 300F was the point where you could safely shut down to avoid coking the oil in the turbo bearings.

The SuperDuty 7.3L's have programming built in to boost the idle speed up at low ambient temps to help prevent wet stacking as well.

 

Thanks for the replies folks. It sounds like Super Duty 7.3's aren't especially vulnerable to wet-stacking. I have a large selection of high idle tunes, as I had a lot of blank positions on the Hydra chip I recently installed. I have 1100, 1200 and 1300 RPM tunes loaded, plus a custom 1300 RPM tune from DP-Tuner that holds the EBV closed.

That EBV Closed tune seems a touch aggressive for warming up a cold engine. RPMs first rise to 1500, then the EBV shuts and it lugs down to 1300. On stock injectors it creates a light haze of black smoke, raising EGTs to approximately 600F pre-turbo.

I still have a few blank spots on the Hydra, and am thinking of re-ordering another EBV-closed high idle tune, but going with a slower engine speed, say 1,100 RPM or so.

Excessive, I know....

 

As Kevin mentioned, the Ford programming will boost RPM on a cold start and ambient temp.

I have found it takes 90-120 seconds before it will increase to around 1,100-RPM.

I have one of the old AIC units on mine (which we had on all our North Slope 7.3's) and it revs to 1,300-RPM.

I do not flip it on until the Ford programming increases to its max after 90-120 seconds.

Personal opinion is I do not want to rev a cold soaked older diesel straight away to 1,300-RPM when the oil is thick.

 

That’s my rule of thumb too. Too bad the original AIC’s are so hard to find, they were pretty slick back in the day.

 

when this was a topic a few years ago I asked a friend who was on his third 7.3L what he knew about this and his reply was let it idle all day, it won't hurt it. His trucks did idle a lot. we are in warm climate so that may not be good universal advice. I did find some info eventually matching what some of the previous commenters said there is little to no evidence this is a problem on 7.3L diesels