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Discussion Starter #1
I was wondering why no one uses turbo timers on our trucks. Do the turbos have great cooling an no heat soak? I have a modified Toyota turbo truck and that was one of the first things that I bought in order to prevent coking of the oil. I also know most turbo rice rockets use turbo timers. I searched this board for "turbo timer" and got no results.
 

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I'm a maintence guy by trade and don't quite understand what a Turbo Timer is or does.


Unlike a gas engine which could run OK without the use of the turbo, the Dmax will run like crap because of the design of the engine requires pressure from the turbocharger.


So what does a turbo timer do?
 

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Discussion Starter #3
Turbo timers keep the engine running after you remove the key. It allows the engine to keep fluids moving at idle which cools the turbo to a safe shut off temperature. If you shut down while the turbo is still VERY hot, the oil will coke. Over time, the oil pathways will look like the plumbing in a 90 year old house.


Here's a random website that came up when I searched google for turbo timer.


http://www.eautoworks.com/html/ape-auto~performance-Turbo~Timer.htm
 

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I believe just as with any aftermarket part there are stands on both sides of the fence. I know gassers use them, but some say we dont need them.
 

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Discussion Starter #5
tanner or anyone,


Do you know the reasoning behind why diesels don't need them? I would think that oil cokes no matter whether it's in a diesel turbo or gas turbo. I could be wrong, but just wanted to know why if I am, so I can put my mind at ease.
 

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IIRC, the turbo on the LB7 is cooled with the engine coolant. I don't recall whether or not the LLY's turbo is cooled the same.
 

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mbeckwith said:
tanner or anyone,


Do you know the reasoning behind why diesels don't need them?  I would think that oil cokes no matter whether it's in a diesel turbo or gas turbo.  I could be wrong, but just wanted to know why if I am, so I can put my mind at ease.
I was always under the impression gassers had higher egts than diesels, but I could be wrong. Higher egts=higher turbo temperatures=more coking if not cooled down.
 

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What is 'COKING', I prefer Pepsi



If it is COOKING the oil I may understand.


The Schaeffer's oil has moly just for that kind of problem and the 7000 blend has a higher temp than dino oil.


If u are running the truck hard for a long time then it could be a problem.


Anytime I'm pulling a loaded trailer i just let it idle while I unload.


I only run 35-40mph on our 2 mile road so normal driving it is cooled down already when I get home.
 

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I will be having a Turbo Timer installed on my truck. The Python Security system/remote starter has one built in. I'm not sure if the Duramax really NEEDS one. However I'm sure it will help over the long run. Especially since I will be getting the Edge when it's available. I would think the EGTs will be higher than stock when running it so it just sounds like good insurance.


I will likely set my TT to run for 1-1.5 minutes after I get out of the truck.
 

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It's a combination of the two: lower overall EGTs and the fact that the DMax turbo has a water-cooled inter-housing (on the LB7s anyway, I don't know about the LLY). Although the water pump stops circulating water when the engine stops, the volume of water in the water jacket still has tremendous heat-soaking capability in the area where oil-coking of the turbo bearing used to be an issue (turbo wheel still spinning on a non-flowing oil volume in the bearing heated by the hot cast iron snail and the wheel on the exhaust side). We do not have any concerns over cooldown or oil coking and the addition of a turbo cooler is unecessary expense, fuel use and intrusion into the truck's circuitry.
 

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Ah, I understand now.


As I understand the cooling system on the LB7 turbos, they're water cooled and not much in the way of cool down is required. I wouldn't worry about it. Most of these guys flog the Duramax and I think only a couple have grenaded a turbo.



I had a 1987 Dodge shadow turbo that was also water cooled. At that time, GM did not put water jackets on their turbos and they lost a few. I never had a problem with that turbo but I didn't keep the car long enough to find out, 130,000 mi. That thing ate carrier bearings though. It peed ATF on the ground as I traded it in for a chevy S-10 Blazer.
 

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The "water cooler" on the LB7 turbo is to aid warm up of the cold coolant and does not help cool the turbo when hot. The LLY does not have it because it has varaiable vanes in the turbo and has exhaust back preasure to aid warm up. I would think a way to lubricate the bearings until the turbo spooled down on shut down would be more important.
 

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dmacy said:
The "water cooler" on the LB7 turbo is to aid warm up of the cold coolant and does not help cool the turbo when hot. The LLY does not have it because it has varaiable vanes in the turbo and has exhaust back preasure to aid warm up. I would think a way to lubricate the bearings until the turbo spooled down on shut down would be more important.

That's certainly a new one on me! I have yet to see a cooling system "heater" (other than a block heater) on any engine. If you've seen that in writing somewhere I'd sure be interested in seeing it. All of my research and understanding of the COOLING system on the DMax is for heat removal from the turbo, heads, oil, etc.
 

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dmacy, I stand corrected - I did some further research and apparently the turbo water jacket IS thermostatically bypassed when coolant is up to temperature and is a warmup feature! (SAE paper 2001-01-2703) I still feel that the added material and water volume in the turbo housing between the turbine and compressor stages provides a "heat sink" to help prevent bearing oil coking - but you are absolutely correct that it is a "warmup feature"!
 

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DavesDmax said:
I'm a maintence guy by trade and don't quite understand what a Turbo Timer is or does.


Unlike a gas engine which could run OK without the use of the turbo, the Dmax will run like crap because of the design of the engine requires pressure from the turbocharger.


So what does a turbo timer do?

Say whaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaat? . . . and you are a maintence guy by what? Is that sanitation?
 

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That would be Industrial maintenance guy.


We have a turbo on our EMD emergency Diesel Generators and no turbo timers. When the engine is shutdown the Aux oil pumps and the Turbocharger soak-back pump kick in. The turbo on an EMD is a wee bit bigger than the Dmax. About a 17" wheel if I remember correctly. It also has a neat feature of being both a gear driven and exhaust driven Turbocharger. Under no-load condition, the EMD does not produce enough exhaust to provide scavaging air in sufficient so the gear drive spins the turbo at sufficient speed to perform that function. At load, the gear drive is dis-engaged from the turbo by means of an over-run Clutch. 4500 HP Diesel needs to breathe a little.



I do understand the concept of consumer grade shutdown timers for vehicles, just never seen any. I would think that there is a better way of dealing with heat removal of the turbo by running a aux oil pump for after run conditions to remove heat. The water jacket on the turbo will perform the same function whether it is a warm-up feature or not. In a shutdown condition, the diesel is no longer producing heat and the ample water jacket will provide cooling to those components that still have a heat load.
 

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If you watch your exhaust temps and get them below 350 or 400 (assuming you have an EGT gauge), shouldn't you be fine? It doesn't take long for it to cool down, even in our 100+ time of year.
 

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The turbo and associated piping is also aluminum. It dissipates heat very fast. It does not take long after exiting the freeway with my trailer in tow before the EGT is down to 350 or so. Later! Frank
 

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Discussion Starter #20
Just thought here...


If a chip/power mod company came out w/ a turbo timer feature or option to their programmer/chip... I would consider buying it. I don't know if the power mods can even tap into something like that, but it would be a cool add-on feature to help a heavily worked turbo.
 
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