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Turbo question


Thirdeep's Avatar
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03-31-03, 12:54 PM   #1  
Thirdeep
Turbo question

I have a cummins diesel and i took the hose off between the air filter and the turbo there is a propeller in the turbo should that propeller be spinning when the engine is running at idle? mine does not,but i can turn it with my finger i dont know how free spinning they should be or is it because i have the hose disconnected that it did not spin. thanks for all replies

 
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WeldGod's Avatar
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04-01-03, 12:48 AM   #2  
First off all KEEP YOUR FINGER OUT of the turbo! It would help if you would tell us what year the truck is. I guess you are talking about the cross over hose? It might not spin at idle with the cross over hose disconnected; even with it connected it would not be spinning very fast. By removing the crossover you decrease air flow over the impeller. There should be an oil line in to the impeller on the top, you might pull it off and blow it out. After that if you are not sure it is getting oil, you can put it all back together and pull off the oil drain tube on the bottom and put a can under the hole and fire it up and see if you are having oil flow.

 
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04-01-03, 03:14 AM   #3  
Joe_F
I agree with Weld. Also, get the appropriate vehicle service manual---it will answer all your questions.

 
turbojimmy's Avatar
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NJ

04-02-03, 06:18 AM   #4  
Re: Turbo question

Originally posted by Thirdeep
I have a cummins diesel and i took the hose off between the air filter and the turbo there is a propeller in the turbo should that propeller be spinning when the engine is running at idle? mine does not,but i can turn it with my finger i dont know how free spinning they should be or is it because i have the hose disconnected that it did not spin. thanks for all replies
Not sure if you're trying to solve a specific problem or if you're just curious but...

At idle, the impeller blades will either be spinning very slowly or not at all. There are 2 sets of impeller blades - one set is driven by the exhaust gasses (you can't see these unless you remove the downpipe), the other is in the intake tract to pressurize the incoming air (these are the ones you can see when you remove your intake pipe). They are connected to each other via a shaft in the impeller housing (which is what the oil feed is for - to lubiricate the shaft and bearings). A turbo is driven by exhaust gasses which is a function of RPM and load. At idle, there isn't much of either so the turbo isn't doing much. That's why there's "turbo lag". When accelerating, it takes a few seconds to get enough gasses moving for the turbo to spool (when you actually begin to hear the turbo).

If you suspect something is wrong with it, check for end play and make sure that the blades spin freely with the engine OFF. Make sure there's no oil on the intake side of the impeller blades, too. Any play and/or oil could indicate a bearing problem.

In any event, if the engine is running you really shouldn't stick your fingers in there if you want to keep them in tact.

 
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