Turbo cool down period

[CUMMINSDIESELPWR]

i think one thing that is missed in this discussion is the cumulative effects of high turbo temp shutdown causing the coking.The time it takes for the oil to actually BBQ in the turbo probably is around the time that the turbo actually starts getting below the coking temp. But that small overlapping timeframe over and over again from heavy towing/no cooldown could be causing the cumulative buildup of coked oil in the bearing race.For us daily drivers, we shut down with minimal cooldown but yet there are no problems. Those that have had turbo bearing failure probably got the turbo real hot, and shutdown with non-sufficient cooldown times thus causing the buildup over time leading to failure.thoughts?

[ISX]

I'll show you guys something interesting. Pics of my turbo after taking it apart. Probably 300k miles of buildup.

Here is the shaft I pulled out.

and the brand new one I got.

I polished the other one up and that back half took forever. It is very close to the exhaust gasses itself being that that is the turbine and it shows that the oil gets hot.

Thing is, putting that new shaft in helped turbo spoolup tremendously. I should take it apart again and see what it looks like since it probably has 10k miles on it now.

[22george]

Great info!!!!Thanks

[KATOOM]

Great photos ISX. Tells the true tale about whats going on.And I think that CUMMINSDIESELPWR is right on the money regarding cumulative hot shutdowns. This would be something that would happen over a period of time for the average vehicle. Matter of fact, somewhere I was reading that another common problem with turbo engines is people who dont allow enough start up idle time for the oil to properly circulate through the engine and turbo before reving the engine or taking off. Until the oil is fluid, the turbo bearings are basically running dry but the shaft will still spin in relation to the engines RPM's. Bad for the bushing and shaft.

[AABEAR]

When I am pulling my fifth wheel I planed my stops so that way I start slowing down so it will cool down on it Owen. I will let it idle for about 2 mints then shut down.

[KATOOM]

Not to hijack the thread but in relation to the OP topic..... Turbo cool down timers seem like a great option so ya wouldn't have to wait around for the truck to cool down to a desired EGT. But I tried one years ago and it was terrible. Not only did it cause some warning dash lights to come on upon shutting the truck off but you also couldn't lock the doors either which meant walking away from a running truck.....with the doors unlocked. Not something most people feel comfortable with, depending on where you live.

[gassernomore]

Turbo cool down timers seem like a great option so ya wouldn't have to wait around for the truck to cool down to a desired EGT. But I tried one years ago and it was terrible. Not only did it cause some warning dash lights to come on upon shutting the truck off but you also couldn't lock the doors either which meant walking away from a running truck.....with the doors unlocked.

I have one on my truck. Can set it for 1-5 minutes or forever. Have not had any problems with it. Doors can be locked plus, even if I leave it unlocked and you press the brake pedal it shuts everything down until the key is used again.

[Mopar1973Man]

Interesting conversation between ISX and Katoom... Might have you two compile that conversation into a write up...

[pepsi71ocean]

Interesting conversation between ISX and Katoom... Might have you two compile that conversation into a write up...

i agree. my .02c once your on idle and your coasting for example i have noticed that exhaust temperatures will drop off if the truck is moving, and coasting at the same time. i believe that provided you wait the exra few mins till it hits 250-300 then your safe. once your not powering the oil cooler will draw excess heat away from the oil before it goes through the turbo, combind with the engines cooled piston temperatures will allow for cooler air to go through and cool the metal, and the oil will draw the metal temperature down below the 350F by the time egt's hit 300. by waiting till you hit 250F your exhaust turbine side is (outside with a temp gun), colder then the exhaust air inside the turbo. and thus your turbo will also be colder as well. oil will not coke when the median temp is below the 350F mark.

[Mopar1973Man]

I think this article has earn the right to be transfered over to the tech articles.

[white01]

i have an edge juice with attitude...do not pull anything....i have the timer set for two minutes..shuts down by itself...260-270*..

[2500ctd]

I just get out and turn the key off. Before I used to wait till around 300. Now with my alarm it has a turbo timer. Set it at 3min for now. During normal driving the egt's are under 300 within a minute. 2 more mins cant hurt. Also the remote start set for 12min. Towing I will probably activate the the remote start for the 12min cool down. I used to coast down to a stop but like stated to me that is a false indication due to the engine just pumping air. I came to that conclusion coasting down a hill on i10 in cali. the egts' got down to 180. once the road started to level off the egts slowly came back up. I drive to my spot normal and just waited till it colled down. Unlike the average guy that has a big 5th wheel, pull off the interstate stops and kills the truck as I am still waiting for my egt's to cool down. I do like the idea of an oil temp gauge. Something else to add on. For the oil we could try an oil accumulator. one version and a Tech article on it. We would need to use a small orifice to make the volume last a bit, OR for pumping a small differential oil pump and a small cooler on a timer. Diff pump and a Factory application. Now we could also run the oil through a secondary toliet paper style filter as well. That way cool the turbo and fine filter the oil.

[joecool911]

Did you find an "oil temp" gauge? Interested in this concept as well for my truck.

[eddielee]

After reading this thread I say driving slowly is the most effective way to cool the engine and components. More air flowing through the engine and past the truck. sitting in one spot the warmer air can circulate back through the radiator...I would say for exact numbers installing a temp sensor to the turbo housing would give the best results, however, complicated to install without effecting its ability to release heat.Reading this thread I thing installing one on the return oil line would be second most beneficial, or installation of an electric pump with thermostatic shut off set for 200* would be most ideal.

[mopartechnician]

Somewhere dodge has a tsb for proper idle times depending on load and driving. As you may know idleing is not good on these engines espcially 03 and newer. I have my turbo timer ser on my adrenaline for 350 in the winter and 300 for summer. When dding it usually shuts off when im about 20 yards from the truck.

[KATOOM]

After reading this thread I say driving slowly is the most effective way to cool the engine and components. More air flowing through the engine and past the truck. sitting in one spot the warmer air can circulate back through the radiator... I would say for exact numbers installing a temp sensor to the turbo housing would give the best results, however, complicated to install without effecting its ability to release heat. Reading this thread I thing installing one on the return oil line would be second most beneficial, or installation of an electric pump with thermostatic shut off set for 200* would be most ideal.

As much as these forums are great bases for knowledge.....they're also great ways to cause unnecessary anxiety too. In point, dont be so concerned about the shut down temps. As long as the EGT's aren't well above 300* you're fine. Following the Cummins shut down procedure is ample enough to assuring shut down temps, and yes, having a pyrometer installed is always the best way to determine EGT's.

[AH64ID]

The general rule of thumb I have always heard is 250 for a oil cooled turbo, and 350 for a water cooled turbo (reminder the 6.7 has a water cooled electronics section, not bearing).

To to me a turbo timer based on time is useless, the time required varies based on use, ambient temp, etc.. If you don't want to watch you pyro, or don't trust various drivers to, a timer based on EGTs with the probe post-turbo is preferred.

At idle the post turbo temps will actually increase if the turbo is heat-soaked over pre-turbo temps, which is why post-turbo temps are the most accurate for shutdown.

- - - Updated - - -

Somewhere dodge has a tsb for proper idle times depending on load and driving. As you may know idleing is not good on these engines espcially 03 and newer. I have my turbo timer ser on my adrenaline for 350 in the winter and 300 for summer. When dding it usually shuts off when im about 20 yards from the truck.

It's not too bad to idle a hot motor as a cold one, and Cummins has the same warning and time limits on cold idling for all 5.9's regardless of injection system.

This is the same in all the owners manuals I have looked at.

After reading this thread I say driving slowly is the most effective way to cool the engine and components. More air flowing through the engine and past the truck. sitting in one spot the warmer air can circulate back through the radiator...

I would say for exact numbers installing a temp sensor to the turbo housing would give the best results, however, complicated to install without effecting its ability to release heat.

Reading this thread I thing installing one on the return oil line would be second most beneficial, or installation of an electric pump with thermostatic shut off set for 200* would be most ideal.

When I have been towing I try to do the last half mile or so a little slower in a higher gear, don't use exhaust brake, and downshift while braking to increase airflow. Then i use fast idle for a few minutes (depending on pyro, coolant, and ambient), then a little on low idle and off. I have my gauges wired to run for 2 minutes after shutdown and if the pyro increases more than 50 I know there is still too much heat in the turbo and will idle it again, this rarely happens.

Just moving oil thru a stationary turbo will not cool it as well as a short idle time. If you really want to monitor mainly for turbo shutdown install a post-turbo pyro.

[mopartechnician]

Thats the chart

[JOHNFAK]

Not to hijack the thread but in relation to the OP topic..... Turbo cool down timers seem like a great option so ya wouldn't have to wait around for the truck to cool down to a desired EGT. But I tried one years ago and it was terrible. Not only did it cause some warning dash lights to come on upon shutting the truck off but you also couldn't lock the doors either which meant walking away from a running truck.....with the doors unlocked. Not something most people feel comfortable with, depending on where you live.

I had 2-3 on my old truck - never had an issue. New truck doesnt have one. The guy who built it says he was told by one of the main aftermarket builders not to worry with cooling down the turbo oil return ...... pure heresay right now ....... but Im pretty sure he had that conversation. Im actually going to PM the builder sometime next couple days ..... I'll post back.

[06redcummins]

Never above 350, usually only takes 15 seconds or so to get there