Debate: Metal Impeller water pump, or OEM spec composite?

[Deanx2009]

Pros and cons of both. help solve this problem

m50 1994 525i

[Blauanzug]

metal no question. because the metal was oem for later cars. No question. End discussion. lol

[attack eagle]

they have gone back to composites now... I'd prefer metal. never seen a metal impeller separate from the shaft.

[Sam Son]

there is no debate
just buy the metal one
/thread

[russiankid]

Metal.

[Deanx2009]

Hm everyone says metal, but don't you think BMW is doing something right by remanufacturing composite?

[Blauanzug]

no they want you to come in for more service. When I was at the bmw dealership we saw many more composite water pump problems than metal ones.
Possibly weight? that perfect 50/50 weight distribution.

[4500 RPM]

The metal is heavier, which is harder on the bearings. I have the original waterpump at 132k, not sure if that's an achievement or not.

[russiankid]

Hm everyone says metal, but don't you think BMW is doing something right by remanufacturing composite?

Well just about every other car manufacturer uses metal. Plastic sucks.

[Sam Son]

Hm everyone says metal, but don't you think BMW is doing something right by remanufacturing composite?
BMW is also producing the E60 the E90 that horrendous 7 series and that aborted whale fetus known as the X6so what does that tell you

The metal is heavier, which is harder on the bearings. I have the original waterpump at 132k, not sure if that's an achievement or not.
i had my original one til over 185k

[Blauanzug]

BMW is also producing the aborted whale fetus known as the X6
:lol:evil2

[russiankid]

I had my original at 116k, along with the thermostat. Thermostat was stuck open and the pump was actually clean. I guess the system was flushed every now and then.

[4500 RPM]

BMW is also producing the E60 the E90 that horrendous 7 series and that aborted whale fetus known as the X6so what does that tell you

i had my original one til over 185k

Those cars are my dream cars, especially the X6xdrive35i :rofl

Good know know on the WP...are ours composite? How can one complain about a 185k mile waterpump.

[Blauanzug]

my pump went at 70k :( but that could be because the plastic cracked and broke... so ....

[russiankid]

Those cars are my dream cars, especially the X6xdrive35i :rofl

Good know know on the WP...are ours composite? How can one complain about a 185k mile waterpump.

I'd be paranoid about having a waterpump that is over 70k miles old. I'd probably replace it, along with the thermostat and rad hoses.

[zubbie]

lets clear the confusion here; there were actually 3 different styles.

1. early plastic water pumps that are no longer in production
2. metal pumps
3. composite pumps (which are not the same as plastic)

The argument between the metal and composite really shouldn't matter as long as you do the right thing and change it out every 100K anyhow

[russiankid]

I have the metal Graf pump. Has been in there for 3k miles without any complaints.

[zubbie]

I have the metal Graf pump. Has been in there for 3k miles without any complaints.

my first choice also

[russiankid]

While you're doing your pump, do the thermostat, metal thermostat housing upgrade, radiator hoses, heater hoses, belts, and pulleys. Better be safe than sorry.

[5mall5nail5]

I am running EMP Stewart upgrade pump, so far so good, but I've had friends who have had some issues in the past

[Sam Son]

Those cars are my dream cars, especially the X6xdrive35i :rofl

Good know know on the WP...are ours composite? How can one complain about a 185k mile waterpump.
yup ours are composite
so really i guess all i did was to prove that the compostie ones arent so bad....mine was still good when i replaced it:rolleyes
but i figured if i was overhauling the cooling system i might as well do the pump also

[E34nication]

i need to check my records... i could very well be on my original pump (122k)... can't remember.

[Binjammin]

Hm everyone says metal, but don't you think BMW is doing something right by remanufacturing composite?

They're doing something right; they're making cheaper, lighter parts. I'd avoid a composite impeller pump, go metal all the way.

[Blauanzug]

Benjamin has spoken, the law had been set. Thou shalt not argue with benjamin nei covet thines idea's.
Benjamin's word is final.

[4500 RPM]

Benjamin has spoken, the law had been set. Thou shalt not argue with benjamin nei covet thines idea's.
Benjamin's word is final.

Lowell's word is final. Bin's is served with a side of granular salt.

[WolfStrong]

lets clear the confusion here; there were actually 3 different styles.

1. early plastic water pumps that are no longer in production
2. metal pumps
3. composite pumps (which are not the same as plastic)

The argument between the metal and composite really shouldn't matter as long as you do the right thing and change it out every 100K anyhow

Correct! The early plastic ones were known to fatigue and fail, so BMW went to metal. The problem with the metal ones is that while failure rates were lower, they were still existent and posed an even greater problem with metal shavings in a failed water pump that would tear up the engine! After this, BMW went to a composite pump which has, believe it or not, the lowest failure rate so far compared to the other BMW pumps. I just replaced mine with the composite pump and I can tell you, it feels STRONG as if it is made of metal; much more robust than the plastic one I replaced it with.

[Binjammin]

Hell I'll default to Lowell when it comes to Bimmers. I've been fixing cars for a long time, he's been fixing bmws for a long time. Can't argue/wiseass my way to more experience :D

[4500 RPM]

Hell I'll default to Lowell when it comes to Bimmers. I've been fixing cars for a long time, he's been fixing bmws for a long time. Can't argue/wiseass my way to more experience :D

My statement was in jest. :D

[Binjammin]

Correct! The early plastic ones were known to fatigue and fail, so BMW went to metal. The problem with the metal ones is that while failure rates were lower, they were still existent and posed an even greater problem with metal shavings in a failed water pump that would tear up the engine! After this, BMW went to a composite pump which has, believe it or not, the lowest failure rate so far compared to the other BMW pumps. I just replaced mine with the composite pump and I can tell you, it feels STRONG as if it is made of metal; much more robust than the plastic one I replaced it with.

The problem is that with a composite, after 10 years it won't look nearly as sturdy, while metal may have some rust on it if you use sub-par coolant, it will still be metal.


My statement was in jest. :D

Maybe, but that doesn't make it any less true :)

[TheStigg]

The plastic impeller in my wife's e36 m50 took a dump this summer when I hot footed it over for an emissions test. I replaced it with a Graf metal pump but it has a cheap looking stamped/spot welded sheet metal impeller. After a close inspection, I decided it was better than a plastic one so went ahead and used it. It works ok but the only problem is I can hear the impeller singing, almost like a vacuum leak.

I put a Laso pump in my m30 last year. I was expecting it to have a metal impeller but it came with the updated composite plastic with a serrated brass hub. I figure if Laso uses plastic, I'd trust it for another 100k.

Both motors cool fine.

[5mall5nail5]

The NEW composite impellers are fine and dare I say good. The NEW metal ones are sometimes just spot welded sheetmetal.

I wouldnt mind running a new OE composite unit.

[ross1]

Have any of you EVER seen a metal impeller disintegrate?
Regardless of much better new composites may be I'll stay with metal. Are the bearings are so marginal that a tiny difference in mass between plastic/composite vs metal makes a difference.

[zubbie]

The argument between the metal and composite really shouldn't matter as long as you do the right thing and change it out every 100K anyhow

to quote myself...preventative maintenance makes any discussion moot.
(is this a form of electronic masterbation? :bj)

[WolfStrong]

to quote myself...preventative maintenance makes any discussion moot.
(is this a form of electronic masterbation? :bj)
Amen!

[mikemxbike4]

A lot of parts are DESIGNED to fail over time.No bs.Therefore as long as you do your maintenance on time you will not have problems with either one.

[russiankid]

The plastic impeller in my wife's e36 m50 took a dump this summer when I hot footed it over for an emissions test. I replaced it with a Graf metal pump but it has a cheap looking stamped/spot welded sheet metal impeller. After a close inspection, I decided it was better than a plastic one so went ahead and used it. It works ok but the only problem is I can hear the impeller singing, almost like a vacuum leak.

I put a Laso pump in my m30 last year. I was expecting it to have a metal impeller but it came with the updated composite plastic with a serrated brass hub. I figure if Laso uses plastic, I'd trust it for another 100k.

Both motors cool fine.

Odd I have the same pump and noticed the same thing but mine is quiet.