Turbo Life vs. cool down

[TonyB]

So, I have had a 2006 Cummins for just over a year. Typically, I will wait until the exhaust temp hits 300F before shutting down. From an oil perpective, at what temp would be the best for shutting down? I am currently running Valvoline 15W40 (conv). I have had thoughts of Synthetic. How would sythetic affect shutdown temp? If at all?

TIA

Tony

 

[Jim Allen]

You're doing your truck, and ultimately your wallet, a favor. A synthetic may have a higher temperature threshhold but is not immune to oxidation, coking and all the rest of it. FWIW, my truck is celebrating it's 20th year with the same turbo and I have done what you do from day one... 300 degrees has been my benchmark also. Another FWIW is that when I had a infrared heat gun, I found the turbo housing to be a bit cooler than what the pyro read at that 300 degree point.

 

[TonyB]

Jim, thanks for the reply.

One thing that concerns me about idling to cool down is the use of fuel. Ok, well, the cost of using the fuel. At least with the pyro I know I am cooling down enough and not guessing by time.

Thanks again!

Tony

 

[firemediceric]

There is really nothing special about either my truck or my Mercedes diesel. I do run them hard on the interstate, but from the exit ramp to my driveway I take it easy and often hit a couple of traffic lights where I sit for a minute or two. I think this is plenty to cool off the turbo without letting it idle longer once I get to my destination.

I don't have a gauge to know what temps I'm getting, but the turbo in the Mercedes is 26 years old and still going strong

 

[LateArrivalforLSU]

Quote:

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So, I have had a 2006 Cummins for just over a year. Typically, I will wait until the exhaust temp hits 300F before shutting down. From an oil perpective, at what temp would be the best for shutting down? I am currently running Valvoline 15W40 (conv). I have had thoughts of Synthetic. How would sythetic affect shutdown temp? If at all?

TIA

Tony

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Is that 300 degrees pre or post turbo temps?

 

[widman]

I don't have a temp guage on it, but am very careful about letting my 4Runner Turbo diesel cool several minutes after I get to the office at the end of a straight 60 mph run for 20 min up the mountain.
When I first bought my Mitsubishi Fuso, one of my salesman blew the bearing on his first trip. Turned off the engine after a 50 mph cruise and then restarted after watering the road. No cooling. froze the bearing.

 

[Jim Allen]

TonyB-

The only time you really need to worry is coming off the freeway or stopping after a long pull. Around town, you barely get to 300 anyway and as one poster said, coasting down the offramp, idloing at the stop light, etc., usually will get you there anyway. Your fuel economy concerns are well-founded but I guess the main point is to just to train yourself to look at the gauge and give it the time to cool off when it needs it. Dependig on how you use the truck, that may only be a small percentage of the time.

 

[TonyB]

Quote:

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Is that 300 degrees pre or post turbo temps?

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Pre turbo...

 

[TonyB]

Quote:

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TonyB-

The only time you really need to worry is coming off the freeway or stopping after a long pull. Around town, you barely get to 300 anyway and as one poster said, coasting down the offramp, idloing at the stop light, etc., usually will get you there anyway. Your fuel economy concerns are well-founded but I guess the main point is to just to train yourself to look at the gauge and give it the time to cool off when it needs it. Dependig on how you use the truck, that may only be a small percentage of the time.

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Jim,
Even after idling through the parking lot, the exhaust is still at 400F. I hit the hi idle (1500 rpm) to get more air under no load & cool down to about 350. Drop the idle to 1100 for about 15 seconds. As it crosses 325, i'll kill the hi idle and let it idle at ~700 until it crosses 300F.

Yes, I am anal...engineers are built that way.

Thanks for the replies...looks like i'll just keep doing what i am doing...

Tony

 

[Griz95]

I agree with Tony, even after running around town my turbo temperatures can be 400 degrees when I come to a stop. If 300 degrees is the ideal shut down temperature then you are too hot. But all this depends on your vehicle. Some vehicles turbo cool down might not be a problem. I believe in trucks though it would be wise to monitor your turbo temperature especially when towing.

I am monitoring the pre-turbo temperatures.

 

[wileyE]

Put a heinki (sp?) idle timer and an oil accumulator on my toyota gas turbo. Ran valvoline turbo oil for the 1st 90k, then sold it to bud who used mobil1 or syntec from costco. Truck now has over 200k on it and stills runs strong. I blew a head gasket once and the hose off the turbo a couple times when I had the boost cranked up, but never hurt the motor.

 

[Griz95]

I installed a Turbo Lifesaver on mine. Saves me time waiting for the turbo to cool down in the parking lots.

I just set it to run a certain amount of minutes, take the key out and lock the truck up and walk away.

Griz95

 

[tsmay51]

I have an o3 ctd. I do my best to let it cool down when I can or if I am working it hard. I am sure it is good for the truck in the long run but my brother has an 89 model with over 500k and a 96 model with over 280k. He maintains both trucks very well but has never let them cool down. They have been worked hard in Texas where it gets plenty hot in the summer. He has replaced lift pumps, injectors, and other small things but never a problem out of the turbos. They are pretty bullet proof at least for him they have been. I would still let it cool down but imo the turbo is one of the last things to worry about on these trucks.

 

[cowpie1]

I gave up using any turbo temp gauges in my semi's since about '92. Just wasn't worth cluttering up dash with temp gauges for turbo, diffs, and transmission anymore with high quality synthetics.

Oh... if this seems foolish, I have NEVER lost a turbo in almost 20 years of driving approx 130K miles a year and putting 1.4 million miles on my last semi, a '96 with Cummins N14.

A lot of what is said here is true... the time is takes to get thru a couple of lights on the street and pulling in to park will cool the turbo. Unless you are on a hard pull, at high power, etc. and then just reach over and turn the key off, you will probably not have a turbo cool down problem.

With the new variable vane, computer controlled turbos, the risk of turbo cooking is not nearly as big a problem as it was 2-3 decades ago. Take a look at this from Banks... especially myth #7:

http://www.bankspower.com/tech_TD-fact-Fiction.cfm

 

[M1Accord]

My neighbor has a Mercedes turbo diesel car. It takes about 5 minutes or 1 mile doing 20 mph down hill from the subdivision entrance to his driveway. He indicates that it is enough to let the turbo cool down. But he always let the engine runs, get out of the car and pop the hood, then go turn off the car. He parks it in the garage every night and leave the hood open like that. That additional 30 seconds does help cool it system down some, probably 30 to 40 degree. As far as fuel consumption goes, vehicle use very very very very little fuel when idle. The extra fuel burned by letting car cool down may add up to about 5 bucks a year. You get a much longer turbo life and a peace of mind knowing you take care of your toy.

For me, I just drink coffee at home and allocate the extra saving toward maintenance for my vehicles.

 

[JHZR2]

diesels use very little fuel at idle, but tend to soot up - not the best, particularly if the MB diesel is an older OM617 or similar series. Diesels cant always even keep themselves warm, thus why idling is a bad thing to do - but youre right, a few minutes wont cost or kill anything.

Ga$$ers waste more fuel at idle, though still very little. They are less efficient, and can easily overheat at idle if your cooling system isnt up to snuff. Id be more worried about how a turbo equipped car is managed ECu-wise, and what it does to the cat at longish idles. Likely not enough to matter, but who knows?!?!

JMH

 

[allan5oh]

considering EGT's on a gasser don't go down very much at idle, I don't see the point. Especially with a water cooled turbo.

Diesels are a different story, but I find by the time I'm parked, the EGT gauge is hovering around 300-350 anyways. Obviously the journal and oil is going to be much cooler then that.

 

[Shannow]

Generally, I don't idle my turbodiesel down, as I've a couple of km of light load town running before I get home after the highway bit.

Looking at costs, I'd be more worried about the soot and blowby from prolonged idling than the risk of turbo damage.

That being said, if I pull into a service station alongside the highway, I'm grateful if I have to wait for a bowser, and then leave the engine idle while I undo seatbelt and those little things.

 

[trik396]

I run my turbo timer for around 3 minutes in hotter temps and maybe 1 and a half minutes in colder weather. Just makes sense when you consider the speed the turbine is at when driving and it may take some time for it to slow down. Wouldn't want that thing to be spinning at 30,000 rpms at shutdown.

 

[JHZR2]

I cant imagine the momentum is that great, especailly considering the no slip condition of flow at the urface of the turbine with respect to a slower flowing gas.

But given your upped specs, there may be a LOT more heat than the normal vehicle.

JMH