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Thought I'd share some pictures of the OEM VDO/Siemens fuel pump taken apart. The brushes of this pump were near end of life and I had changed it about years ago, it was the factory pump.

I had no idea that petrol passes through the entire motor and brushes area. this means that the pump is lubricated/cooled by petrol nomatter the fuel level..

Removed the external shell with a cutting disk. rest can be taken apart by hand.































 

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I had no idea that petrol passes through the entire motor and brushes area. this means that the pump is lubricated/cooled by petrol nomatter the fuel level..
interesting, thanks. this must be how i killed the pump with low quality gas/petrol years ago.
 

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Wow, cool. I just replace my pump and filter, car has 236,000 miles on it and the change in performance was drastic. I also got new upstream O2 sensors but decided not to use them just yet because the engine feels so much better I dont wann eff with it right now.

My new pump and filter made a huge difference in performance, just as much as new B6 dampeners on the corners.
 

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If the pump is lubricated by gasoline, which is a pretty poor lubricant, I wonder if the life of the pump could be extended appreciably by adding a small amount of two-stroke oil to the fuel. I think a small amount would be tolerated by the cats.
 

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If the pump is lubricated by gasoline, which is a pretty poor lubricant, I wonder if the life of the pump could be extended appreciably by adding a small amount of two-stroke oil to the fuel. I think a small amount would be tolerated by the cats.
It needs coolant far more than lubricant.
 

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Adding any oil to the gas in not a good idea ! I don't believe there would be any measurable increase in fuel pump life but over time there will be many problems with other items related to the fuel system. BMW is not alone with this fuel pump arrangement - pretty standard in the industry.
 

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The weak link of these pumps are the brushes and commutator. Could the OP remove the brushes to show their length and the rotor's commutator condition? They could easily use brushless motor instead and it would last longer than the car.
 

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2003 M3 6MT Slicktop
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The weak link of these pumps are the brushes and commutator. Could the OP remove the brushes to show their length and the rotor's commutator condition?
it’s almost never the brushes. people getting over 200,000 miles and 20 years later on original pumps.
true it is a weak link, but not the weakest link.

running them low-empty overheating and poor fuel quality the biggest killers. followed by overworking them from crud-filled choked filters.
 

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Very cool. Thanks for sharing.

I have the feeling that a fuel pump is in my near future, so this is especially useful.

What does the fuel level sensor arrangement look like? I have never had one out on an E46.
 

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If the pump is lubricated by gasoline, which is a pretty poor lubricant, I wonder if the life of the pump could be extended appreciably by adding a small amount of two-stroke oil to the fuel. I think a small amount would be tolerated by the cats.


Refineries use additives in the gas to assist in lubrication. That’s why cheap gas can kill a pump


Sent from my iPhone using E46Fanatics mobile app
 

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Refineries use additives in the gas to assist in lubrication. That’s why cheap gas can kill a pump

Sent from my iPhone using E46Fanatics mobile app
Exactly. Which is why it's *possible* that a small amount of additional lubricant might help pump life. 2 stroke oil is designed to stay mixed with gasoline, and it is designed to burn cleanly without ash or carbon deposits. I doubt it would be harmful to anything (at reasonable ratios, say 100:1 or less). Whether it would be helpful is unknown.
 

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it’s almost never the brushes. people getting over 200,000 miles and 20 years later on original pumps.
true it is a weak link, but not the weakest link.

running them low-empty overheating and poor fuel quality the biggest killers. followed by overworking them from crud-filled choked filters.
What parts fail due to those causes?
 

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hey there,so if collector worns out, its a huge coolant problem of this pump....i see...
if the carbons were worn first, then its the speed of the pump/wrong voltage.

we need just lower the voltage for the pump, then it hold minimum double long, but then the pressure goes down with as fast as voltage, im pretty sure u can undervoltage this pump at 20% and its still ok for a non supercharged e46
 
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