Turbo Cool Down time after spirited driving??

[Wiredawg]

The diesel supplement for 2017 covers 1500-5500. You're looking at the 1500 stuff. Try page 133.

As I said, the dual radiator was dropped after 2 years. It was only in pickups from 2013-2014.

As far as your dual radiator, got a pic? The stuff I'm reading says you should have the same cooling setup as the pickup, which is a single radiator.

Just need to be sure you're reading info for your truck.

No, the C&C's don't have more cooling capacity and radiator configuration will have minimal impact on turbo cooldown times.

I stand corrected and you are right. It was a year ago that I actually read it and today I was using the search feature to find the chart to help the OP. Even though he read it, kind of helps to reference it when WAGging the hotrod answer.

My original answer was actually correct on the times. If me I'd give 3 minutes idle if I hotrodded and turned into WalMart. I don't hotrod my 5500 and so the only cooldowns I have really are running empty and towing heavy. My truck weighs 12K Lbs empty, like P/Us running loaded.

Thanks for catching it. I don't want to be one to spread bad info.

Cheers, Ron

 

[Jim W]

So I guess the real question is if turning the engine off prematurely can take thousands of miles off the life of the turbo/engine, why doesn't the onboard computer give some indication light when it is ok or not ok to shut off. Or make it prompt a warning when you attempt to shutoff saying "engine is still cooling and shutoff is not recommended, do you want to continue anyway?" It seems odd that with all this technology and the fact that this is a $65k plus vehicles, there would be a way to prevent this irreparable damage from happening so easily. I mean, I'm an ocd nutjob with my stuff. But most people I know, even mechanics/trademen, rarely, if ever, read an instruction manual, doesn't matter if its a truck or a lawnmower or a gun.

Will at the TDR rally this year you could ask about this question that you have proposed above!

I can also tell you that the design engineers for both Cummins and Ram have thought of this issue and have addressed this issue in the owners and operator manually provided in the truck. Another thing the newer truck turbos are not your grandpa turbos. These have been totally redesign with newer material specifications which specifies higher temp grade material to withstand the higher operating temps that the turbo see. When I was stock with my EGT probe I would routinely see 1450F operating temps when the truck was in the regen mode, this could last up to 10 mins or more.

If you time yourself from a highway speed of 65 MPH pulling a 12K+ load with the EGT's in the neighbor hood of 900F to 1000F and then proceeded into a rest stop on the interstate. You will see that this will take between 2 mins and 4 mins to arrive at a parking place for your truck and trailer. By this time the EGT's have drop to around the 450F and 500F range, one (1) min more and the EGT's will go no lower than 400F. By than it is safe to shut down the engine.

As I stayed in my pervious post on this thread you could idle for an 1 hour or more with a stock 6.7L Cummins truck built after 2007.5 and you will not drop below 400F EGT's. You would only be wasting diesel fuel as you idle and your time.

 

[Aftershock00]

Thank you for the responses. So is a handful of times possibly not waiting long enough a death sentence for the turbo, or is it more a problem where every shutdown for the life of the truck is too quick of a shutdown?

Do you think it’s worth switching to full synthetic instead of the T4 I’ve been using for extra protection and peace of mind? I change oil every 4K miles.

 

[AH64ID]

Its a cumulative type issue when you shutdown too hot.

Why are you changing your oil every 4K miles?

 

[Aftershock00]

This truck is basically my Sunday car. My wife and I both drive older cars to work (I commute 80 miles a day, 4 plus hours in traffic). We work hard for what we have, so this is my Sunday/wedding truck, toy hauler, hot rod, road trip, and sometimes real work.... truck. Put about 6-7k miles a year on it. Change oil twice a year. Spend more time being anal with it (undercoat with fluid film and carwell twice a year) .
I always felt that it’s minimally detrimental to beat on things, as long as everything is properly warmed up and fluids/lubricants are fresh and top notch. I dunno, maybe I’m wrong???? But since I don’t drive it much, it’s nice to go out to dinner and a drink in a high end truck, and on the way home, give the truck a good workout after sitting.

 

[AH64ID]

In that case you could switch to a quality extended life synthetic and just change the oil once a year. Amsoil DME is what I would recommend.

If you're still going to change it twice a year then stick with what you have, or a cheaper synthetic. My dad changes his 2x a year and runs Amsoil ADP.

 

[Wiredawg]

The diesel supplement for 2017 covers 1500-5500. You're looking at the 1500 stuff. Try page 133.

As I said, the dual radiator was dropped after 2 years. It was only in pickups from 2013-2014.

As far as your dual radiator, got a pic? The stuff I'm reading says you should have the same cooling setup as the pickup, which is a single radiator.




Just need to be sure you're reading info for your truck.

No, the C&C's don't have more cooling capacity and radiator configuration will have minimal impact on turbo cooldown times.

I don't have my truck right now to confirm how many radiators it has and I'm only going by what I read. The banner associated with this listed 2013 to 2017 Cab & Chassis.

Also, the turbo is water cooled and if there are any improvements in the engine cooling system, seems there should be improvement in the turbo cooling as well.

 

[Aftershock00]

Thank you for the tip. I always thought amsoil made great stuff and used it in my motocross bike religiously. Being used to air cooled and water cooled/no fan race equipment, I was always told that it was better to shut down ASAP as idling with no movement/air flow would cause it to overheat. Guess now I have to get used to the opposite.

As far as “coking” is concerned, I’m understanding it to be the motor oil equivalent of carmelizing. Would that be reasonable? If so, assuming you don’t continue to coke the oil and layer it up, does the coking layer eventually break up and flow to the oil filter or is it tattooed on there for life ?

Just trying to educate myself....

 

[AH64ID]

I don't have my truck right now to confirm how many radiators it has and I'm only going by what I read. The banner associated with this listed 2013 to 2017 Cab & Chassis.

I'd be interested to see if you have the Y pipe and dual hoses when you get back to your truck.

Also, the turbo is water cooled and if there are any improvements in the engine cooling system, seems there should be improvement in the turbo cooling as well.

Yes and no, the water cooled turbo will resist coking because the heat would have to get thru the coolant into the oil.

I know that the coolant outlet is on the opposite side of the turbo as the inlet, and that coolant flows thru the controller, but I don't know how much of the bearing housing is surrounded by coolant.


Anyhow, I've been using 400° as my shutdown temp and it gets below that temp very quick, except after towing. Cool down is fairly similar to my '05, which also had a water cooled turbo. It will get below 350° after a couple minutes, and that's the most I've idled. I'll watch it closer next time I have some decent idle time.

Thank you for the tip. I always thought amsoil made great stuff and used it in my motocross bike religiously. Being used to air cooled and water cooled/no fan race equipment, I was always told that it was better to shut down ASAP as idling with no movement/air flow would cause it to overheat. Guess now I have to get used to the opposite.

As far as “coking” is concerned, I’m understanding it to be the motor oil equivalent of carmelizing. Would that be reasonable? If so, assuming you don’t continue to coke the oil and layer it up, does the coking layer eventually break up and flow to the oil filter or is it tattooed on there for life ?

Just trying to educate myself....

Yes, that's what coking is. Coking can be very difficult to remove and won't dissipate under normal oil flow/temp.

 

[Timd32]

You can always do a routine Oil Analysis, Blackstone Labs is one of the popular ones out there.

Cost is really low for your change interval. Blackstone only charges once you mail it in, supplies can be requested when you set up your account.

But you can look up other places as well, I used 2 different labs for some work related stuff, some places have a niche for how to interrupt the results.

They can let you know the specifics of what your set up is doing, after a baseline is established they might provide a reccomendation for something.

Also running it hard should be no problem, no sence taking it easy if thats not your style. We always ran our stuff pretty hard with minimum breakin, if its going to break get it over with.

We still do the old school 5min cool down with the industrial gen sets (16cyl) even though they have a smart half engine cycle the customer wants them run 5min, then the smart cool down. Some places are finally starting to do just the smart cooldown on the Gen sets.

 

[petersonj]

Being used to air cooled and water cooled/no fan race equipment, I was always told that it was better to shut down ASAP as idling with no movement/air flow would cause it to overheat.

You bring up a good point here. Those engines and all gasoline engines in cars and trucks have a throttle plate that closes when you let off of the throttle. This closed throttle plate greatly reduces the amount of air flow entering the engine and exhaust, in fact the engine will become a vacuum pump. With very little air flowing through the engine cylinders and exhaust, there is very little cooling from what little air is flowing through. I can easily imagine why a piece of "no fan race equipment" would need to be shut down immediately if there was no air flow.

Because a diesel engine does not have a throttle plate, there is always a full charge of air flowing through the engine cylinders and exhaust. So the moment you release the throttle, fueling stops and cooling from air flowing through the engine and exhaust starts immediately. Even when moving heavy loads in city traffic, the engine spends only a brief amount of time under heavy fueling, which is usually followed by slowing or stopping.

It is because of this behavior of air flowing through a diesel engine is why you really don't need to perform cooldowns under normal freeway and city driving, even when towing.

There are definitely times when cooldowns are necessary, but they are rare. If you were towing up a 6% grade for three miles and a flagger ahead was stopping traffic, then you would be a fool to shut off the engine when you stopped your truck, as you would totally disrupt any cooling for a very heat soaked engine and turbocharger.

As many others have indicated, just use a common sense approach.

My truck has clocked over 300,000 miles (lots of miles towing) on the original turbo and it is still working just fine and I expect that it will continue to do so for awhile longer. I very rarely ever idle for cooldown.

- John

 

[kthaxton]

My 2015 2500 does not have dual radiators, but the 2015 Ram literature said they do.

 

[AH64ID]

Because a diesel engine does not have a throttle plate, there is always a full charge of air flowing through the engine cylinders and exhaust. So the moment you release the throttle, fueling stops and cooling from air flowing through the engine and exhaust starts immediately. Even when moving heavy loads in city traffic, the engine spends only a brief amount of time under heavy fueling, which is usually followed by slowing or stopping.
- John

Have to be careful what engine you're talking about. 5.9's had unrestricted intakes; however, 6.7's do not.

There is a "intake air throttle plate" that will close off to allow more EGR flow, along with the EGR valve. This plate, and use of EGR, is likely why 07.5-12 6.7's idle at higher EGT's than 13+ 6.7's.

 

[petersonj]

Have to be careful what engine you're talking about. 5.9's had unrestricted intakes; however, 6.7's do not.

There is a "intake air throttle plate" that will close off to allow more EGR flow, along with the EGR valve. This plate, and use of EGR, is likely why 07.5-12 6.7's idle at higher EGT's than 13+ 6.7's.

Good point and thank you for the information. Technology is always changing and I am always learning.

- John

 

[Aftershock00]

So the heat in the turbo is created from the high RPM's of the turbo, or from the hot exhaust gases or both?

Also, in keeping with my original scenario...if I have the EB activated, allow the auto transmission to shift into second, lean into for WOT, and then completely let off throttle when almost redlined in second gear, the transmission will not upshift, but instead will hold 2nd gear while the EB provides significant braking power. Does this turbo EB deceleration also create heat, or reduce it?

 

[AH64ID]

It’s mostly hot exhaust gasses.

The EB will crate some heat thru compression, but mostly it just reduces the airflow so it holds the heat in. It just means it takes longer to cool down.

 

[Wiredawg]

I'd be interested to see if you have the Y pipe and dual hoses when you get back to your truck.

John, Got my truck back today and it has a single radiator. Last year, while researching the tech info on the truck, I found the info about the dual radiators on the Cummins website. It's not there anymore, but it wasn't current last year. It's tough to get good info when credible sites have it wrong. So, you were right.

Thanks, Ron

 

[Aftershock00]

Thanks for all your replies guys. I will heed your advice going forward and next oil change, I will use synthetic just to be extra cautious. I still think with all the electronics on this 70k dollar truck, you'd think they have some sort of prevention, or at least notification, that the engine is or isn't ready to be shutdown. At the very least, you'd think they'd incorporate a gauge to show the EGT's so an informed owner can make an educated decision. Seems like a no brainer for the benefit of Ram corporation and the end user.

 

[Too Tall]

I timed it while on the road towing.

 

[JR]

So the heat in the turbo is created from the high RPM's of the turbo, or from the hot exhaust gases or both?

Also, in keeping with my original scenario...if I have the EB activated, allow the auto transmission to shift into second, lean into for WOT, and then completely let off throttle when almost redlined in second gear, the transmission will not upshift, but instead will hold 2nd gear while the EB provides significant braking power. Does this turbo EB deceleration also create heat, or reduce it?

High rpm in itself doesn't create the heat. Sometimes it can actually help to reduce it depending on engine load. Higher rpm = more airflow through the engine to aid in dissipating the heat load compared to lower rpm pulling the same load.

Given your usage and mileage conventional oil would be more than adequate. Current crop diesel oil spec (CK4) is a very robust oil. I push 15k intervals no problem which is typically 9-11 months with good oil analysis - which I do regardless of change intervals just for personal interests.