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Old 01-07-2010, 09:42 AM
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Question Turbo diagnostics while off engine

While I have the exhaust/turbo pulled off, I'm left wondering if I should do anything with the turbo, in terms of rebuilding. So I'm wondering if there's really a good way of determining if it's really needed or not. As far as I can see, there are no visible oil leaks. Last time it was on the car and the car drove, it was generating about 9psi...so it was functional.

But, when trying to manually turn the vanes on the turbo with my fingers, it moves, but instantly stops as soon as I stop applying pressure. How freely should it really spin though? Should I be able to give it a good push and see it spin a few revs before stopping?
Keep in mind that this was attempted while the turbo is sitting in a sub-freezing garage. Would this make a difference?
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Old 01-07-2010, 09:55 AM
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from what I've read if you can wiggle the turbo vanes forwards and back you should rebuild. I dont know of any other indicators other then that.
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Old 01-07-2010, 10:01 AM
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You might want to make a wastegate adjustment at this time. Increasing the boost from 9 psi to 12 psi wouldn't hurt.........if the ALDA is not already against the rail.

The rotor will not spin freely when you rotate it. However, it shouldn't be binding either. No radial movement is permitted. Axially, it should be constrained to almost nothing, as well.
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Old 01-07-2010, 10:08 AM
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Thanks guys. I'll give it a good going over after I pull the whole exhaust/turbo apart from each other.
Brian, on the subject of boost levels, I haven't seen any talk of the Dawes device in quite a while. You have any thoughts on the Dawes or anything else like it?
Haven't touched the ALDA in years. Not sure where it's at, adjustment wise. Even if it's maxed out, increasing boost shouldn't really hurt, right? Or would it cause a lean condition? (if the ALDA is left at its current proper setting)
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Old 01-07-2010, 10:13 AM
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Quote:
Originally Posted by ck42 View Post
Thanks guys. I'll give it a good going over after I pull the whole exhaust/turbo apart from each other.
Brian, on the subject of boost levels, I haven't seen any talk of the Dawes device in quite a while. You have any thoughts on the Dawes or anything else like it?
Haven't touched the ALDA in years. Not sure where it's at, adjustment wise. Even if it's maxed out, increasing boost shouldn't really hurt, right? Or would it cause a lean condition? (if the ALDA is left at its current proper setting)
The Dawes controller makes it a simple matter to adjust the boost. The conventional method is not difficult either, if the turbo is off the engine. The problem is that you're adjusting it blind............you cannot measure your result until it's reinstalled.

If the ALDA is maxed out, increasing boost results in increased charge temperatures to no benefit.

There is no such thing as a "lean condition" when diesels are discussed.
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Old 01-07-2010, 10:37 AM
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Thanks Brian. I've got the Garrett turbo, so I know it's not nearly as easy to make the adjustment...even when it's ON the car. If I can make the ALDA adjustment, another 3psi should certainly be noticeable in the seat.

Quote:
There is no such thing as a "lean condition" when diesels are discussed.
Wish there was a 'slapping myself on the head' smiley. I knew that. LOL
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Old 01-07-2010, 10:45 AM
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Originally Posted by ck42 View Post
Thanks Brian. I've got the Garrett turbo, so I know it's not nearly as easy to make the adjustment...even when it's ON the car. If I can make the ALDA adjustment, another 3psi should certainly be noticeable in the seat.


It's easy to make the adjustment with the turbo off the engine. You can work like a gentleman.

If the ALDA has some headroom a 9psi, no adjustment to it is necessary. Additional boost will provide more fuel.

If you adjust the ALDA, the fuel curve shifts to the left, and you get more fuel earlier in range. I do believe that the result is less boost required for full range, but I haven't confirmed it.

My feeling is that most of these engines need more fuel with an IP adjustment once the boost gets near 12 psi. Once of these days, I'm going to pull the IP and do just that.
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