Turbo Cool Down

[Don]

I had an Edge with Attitude on my 5. 9 that had a cool down feature. I am considering putting on an Edge CTS with the same feature on my 6. 7. My question is, is turbo cool down still necessary on the 6. 7?

Thanks,

Don

 

[Jim W]

No, it is not required with the 6. 7L turbo. The turbo is now watered cooled and is designed to operate at a higher temperature than the 5. 9L turbo did.

In fact do not be surprise to see EGT's in the neighborhood of 1450F when the engine regens it's self to clean the DPF.

The only time you need to let the turbo cool down is after a long up hill tow with your trailer attached to the truck. Your O&M guide in the glove box will inform you of these requirements.

Jim W.

 

[AH64ID]

A cool down is still required, but not as long/cool due to the water cooling. The chart in the owners manual is no different than the 5. 9.

EGT's are hard to use as it may be in regen when you shutdown, but outside of regen I have read 400° is fine for water cooled turbos, thou I still use 350° on my water cooled turbo.

 

[Don]

I did check the chart in the owners manual and it list some time as much as five minutes if I remember correctly. I just don't want to sit in my truck that long doing nothing. I guess I could continue my quest to figure out my on board GPS or something while I am waiting.
Thanks,
Don

 

[AH64ID]

It all depends on how your using the truck, the times are generic based on loads/conditions.

 

[Schumacher]

I also use 400*. Applying the emergency brake will stop the regen.

 

[CRath]

For the record... your turbo is NOT water cooled... the electronics which are mounted to the turbo housing and control the variable geometry function as well as the exhaust brake are the items that are water cooled. If this control box was not cooled it would probably be a puddle of silicone after the first good pull. The reason one needs to cool down a turbo is to allow the turbo the "slow down" and allow the bearings to cool before shutting down the engine therefore cutting off the supply of oil. Turbo 101... as you work your truck and the engine is puiing hard the turbo is spinning extremely fast... think 100,000 RPM... the impellers ride on small bearings that are fed a constant supply of engine oil to lube and cool them. If you shut down an engine right after working it that flow of oil stops but the inpellers are still spinning very fast without oil. Eventually you start to cook oil on those bearings and cause excess wear and probably cook the seals as well. The details of the VGT "variable geometry turbo" were covered in an issue of TDR maybe a year ago or so and explained the inner workings very well.

I have heard of oil pumps that have been installed on heavy equipment that pump oil to the turbo upon engine shutdown to continue the flow of oil for a set time to prolong turbo life. Cooling down your engine and turbo is always a good idea. Hope this clears the air a little.

 

[HBarlow]

I haven't read the owner's manual since I bought my truck in January '08 but I'm thinking it has the identical turbo cool down warning paragraph that my '01 and '06 had. One minute cool down after normal light throttle light load driving and five minutes after full power full load operation.

Like Shumacher above, I always allow cool down to 400* by pyro gauge. If I've been pulling a trailer in highway operation and know it is heat soaked and am in a hurry and don't want to wait for cool down I leave it fast idling and lock the doors when I exit.

Turbos are expensive. My time is not.

 

[Don]

That is more in line with what I was thinking. I will look into an Edge product that will take care of the cool down.
Thanks again,
Don

 

[Jim W]

This is interesting to see that people will try and cool a turbo down to 400F in a stock truck, equipped with a 6. 7L engine. I know the DPF is sooting up from all of this idling waiting for the turbo to cool down and soot is being introduced into the engine by the EGR system. When my truck was stock, I could never get the turbo temperature below 650F, even on a -10 deg day when I tried to let it cool down. The EGR and aftertreament of the exhaust keeps the temperature up on the turbo.

This was one on my reasons for deleting now when I shut the truck off the turbo temperature is between 300 to 350F. When I tow my 5er I only let the engine idle for 1 minute or two before I shut down the engine by this time the turbo temperature is 350F.

Jim W.

 

[BIGNASTY]

I know that you guys are talking about 4th gen and mine is a 3rd gen but it takes your turbo much longer than mine to cool??????? is it BECAUSE OF THE REGEN? equipment. My truck is equipped with a pre luber with post shut down timer Its set for 5 min but thats way to much unless like HB said Im pulling something for a while it takes more than that to cool. Seems weird with all the water/oil cooling of your generation that it would take very long at all to cool

 

[AH64ID]

After a quick run up and down the highway (just did the pyro install) the truck cooled to 400° in under 30 seconds, and 350° in about 2 minutes. It wasn't heat soaked, but did hit 1100° a few times on the drive.

We changed the oil and went back out, this time it got down to about 410° after a minute and wouldn't go and cooler. . silly emissions.

 

[HBarlow]

This is interesting to see that people will try and cool a turbo down to 400F in a stock truck, equipped with a 6. 7L engine. I know the DPF is sooting up from all of this idling waiting for the turbo to cool down and soot is being introduced into the engine by the EGR system. When my truck was stock, I could never get the turbo temperature below 650F, even on a -10 deg day when I tried to let it cool down. The EGR and aftertreament of the exhaust keeps the temperature up on the turbo.
This was one on my reasons for deleting now when I shut the truck off the turbo temperature is between 300 to 350F. When I tow my 5er I only let the engine idle for 1 minute or two before I shut down the engine by this time the turbo temperature is 350F.
Jim W.

Sorry, Jim. I believe you're mistaken.

That can only happen if the engine is in a regen when the truck stops and if the driver allows it to idle for a minute the ECM will terminate the regen and allow temp to drop immediately.

Besides that, all 6. 7 engines 2009 and later and all that have had a reflash have a net zero mode that the engine enters while idling that prevents buildup and reduces soot downstream.

 

[AH64ID]

I don't think Net Zero is always operating, it seems I recall it being a "as needed" thing, along with the 5 minute Net Reduction. It stands to reason thou that either of those would increase EGT's.

 

[Jim W]

Sorry, Jim. I believe you're mistaken.



That can only happen if the engine is in a regen when the truck stops and if the driver allows it to idle for a minute the ECM will terminate the regen and allow temp to drop immediately.



Besides that, all 6. 7 engines 2009 and later and all that have had a reflash have a net zero mode that the engine enters while idling that prevents buildup and reduces soot downstream.

Harvey,

I had the truck re-flashed with the J35 flash from Chrysler when it was first introduced. This was to update the truck to a similar program as the 09's had. I had installed my gage package in March of 08 and the truck ECM had the stock programming in it. My son, who has two 5. 9L equipped trucks was really surprised to see the high EGT's form the gage at idle and operating on the road. When stock I would routinely see 1450F at regen and when it was over the EGT's would drop to 800F. At start up when cold from sitting over night the EGT's would climb to 400F at idle. After driving to work a 30 min drive the EGT's were in the 650F range and I would need to spend at least 15 min's idling for the EGT's to get below the 600F on the gage.

This was one on the major reasons that I deleted the emission package. This was to lower the EGT's on the turbo and not to soot up the engine from extreme idling. Also the extreme idling ruined my fuel economy.

Jim W.

 

[HBarlow]

Jim,

That's not normal. Something has to be wrong for a 6. 7 to produce egt that high at normal idle and remain that high.

 

[Schumacher]

Jim,



400* can easily be reached within 5min, even after a up hill pull. After start up it idles at 300-350*.

 

[Jim W]

Harvey,

I think the truck as built in Nov 07 and in its stock configuration had normal operating tendencies. Each truck built from the same components from a parts bin will operate slightly different. This is due to the tolerances in building the components and software tolerance that are built in. Each truck will be unique to some degree and will drive differently than others.



I have seen tractors come off the assembly line and be so slow that they just make the specifications set up in the testing specs. Than the next tractor off the same assembly line will be a hot rod, similar components from the same parts bin.



The only difference being tolerances were either at the high side of the tolerance range or at the lowest allowance for the tolerance range, thus causing the machine to operate differently.



Same with my truck.



Since I deleted the truck back in 09, I can shut down the truck between 350F and 300F every time. I will normally see 600F to 800F EGT's when I am on the highway and 600F when driving around town. When I tow the 5er in the mountains I have normally have seen between 800F and 1000F EGT's and will cool down by the time I need to shut off the engine in less than 2 min's. I have only seen 1250F once since I deleted and this was in 6th gear pulling up a long 7% grade, I down shifted to 5Th gear and the EGT's drop back to 1000F.



Jim W.

 

[HBarlow]

Jim,

My truck operates identically without being deleted.

 

[AH64ID]

Jim,



My truck operates identically without being deleted.

Your truck also meets less stringent emissions standards.