GT4 Water Pump

[rantarM3]

Just a PSA.

If anyone is planning on replacing their stock water pump, Bimmerworld has a few M3 GT4 water pumps on sale. These are Motorsport pumps and have a metal impeller instead of a plastic one. It seems like a worthwhile upgrade (at the sale price, at least). I picked one up and put it on my shelf for when I refurbish my M3's cooling system.

[FazerBoy]

How easy a job is it to replace the water pump?

[dj_dub]

I replaced mine with this one from FCP Euro which also has a metal impeller:

https://www.fcpeuro.com/products/bmw...in-crp-wpr0047

Cheap price and lifetime warranty, can't beat that!

Changing the water pump is not that hard, just takes a little time and patience. The hardest part for me was getting the belt back on the pulley.

I'd also recommend changing your thermostat and temp sensor while you do this job as preventative maintenance since you're already working in that area.

[FazerBoy]

Originally Posted by dj_dub

I replaced mine with this one from FCP Euro which also has a metal impeller:

https://www.fcpeuro.com/products/bmw...in-crp-wpr0047

Cheap price and lifetime warranty, can't beat that!

Changing the water pump is not that hard, just takes a little time and patience. The hardest part for me was getting the belt back on the pulley.

I'd also recommend changing your thermostat and temp sensor while you do this job as preventative maintenance since you're already working in that area.

Ok thanks.

[GORDON.M3]

Most aftermarket replacement water pumps for the S65 have the metal propellers.

[Scrippy]

Originally Posted by rantarM3

Just a PSA.

If anyone is planning on replacing their stock water pump, Bimmerworld has a few M3 GT4 water pumps on sale. These are Motorsport pumps and have a metal impeller instead of a plastic one. It seems like a worthwhile upgrade (at the sale price, at least). I picked one up and put it on my shelf for when I refurbish my M3's cooling system.

Just wondering if you might have experienced any cooler temps based off common ambient temps after doing this?

[FazerBoy]

Originally Posted by Scrippy

Just wondering if you might have experienced any cooler temps based off common ambient temps after doing this?

What, after putting it on his shelf...? ;-)

[atopa2002]

What ? Is BMW still using plastic impellers
What's the average life span of the stock water pumps ?

[pbonsalb]

In the 7 years I have been active here, I have read next to nothing about water pump failures or radiator failures or expansion tank failures. I have read about thermostat failures.

[admranger]

Originally Posted by atopa2002

What ? Is BMW still using plastic impellers
What's the average life span of the stock water pumps ?

African or European? [/HolyGrail]

The plastics have gotten a whole lot better since the first plastic impeller water pumps came out (and self disassembled).

[Scrippy]

Originally Posted by atopa2002

What ? Is BMW still using plastic impellers
What's the average life span of the stock water pumps ?

Unfortunately BMW doesn't want us keeping an E92 M3 for too long. They'd prefer we get the new model every 2-4 years.

[lutfy]

Originally Posted by admranger

African or European? [/HolyGrail]

The plastics have gotten a whole lot better since the first plastic impeller water pumps came out (and self disassembled).

Agreed! E36 ones were a ticking time bomb. Never heard anything bad about these (E9x).

Lutfy

[Richbot]

All metal impellers are not created equal. Looks like the aftermarket metal impellers have a significantly thicker vane than the GT4 impeller and the stock composite impeller, would have to spin it at the rpm the pump sees at 6k+ to see if it starts cavitating earlier or later than the stock or GT4 setups, but something to think about

GT4:




Stock replacement from ECS:



Genuine BMW stock replacement:

[BrewRifle]

Originally Posted by lutfy

Agreed! E36 ones were a ticking time bomb. Never heard anything bad about these (E9x).

Lutfy

Mine disintegrated on my E36 M3 while on the highway causing the car to overheat and warp the head.

[rantarM3]

Originally Posted by Richbot

All metal impellers are not created equal. Looks like the aftermarket metal impellers have a significantly thicker vane than the GT4 impeller and the stock composite impeller, would have to spin it at the rpm the pump sees at 6k+ to see if it starts cavitating earlier or later than the stock or GT4 setups, but something to think about

I had not noticed that until you pointed it out. It's also interesting that Motorsport did not want the plastic impeller on their pumps, even though they seem relatively stout.

Originally Posted by BrewRifle

Mine disintegrated on my E36 M3 while on the highway causing the car to overheat and warp the head.

I keep wondering about the small black specs I find when I do coolant changes on my car. I suspect they are pieces of plastic from something in the system but there's no way to know from what (e.g., impeller, hose connections, reservoir, radiator sides, etc.).

[pbonsalb]

I wonder who makes the Motorsport one and whether it is being sold as one of the aftermarket replacements.

For the E36, Stewart GMP makes a very nice billet impeller pump - I have run one for about 10 years. Testing showed it outflowed the BMW pump and was less prone to cavitation.

[dj_dub]

Just because we haven't seen or heard any issues with the factory stock impellers/water pumps, doesn't mean they can't become an issue or either nobody has reported any on the interwebz. If I was already replacing the thermostat and temp sensor, IMO it's smart to change the water pump as well since you're already working in that area. Doesn't cost much and not too much added work involved...better safe than sorry.

After taking out my stock water pump, I placed it on my garage floor vertically and it lightly fell on it's side, the plastic impeller broke easily. It was pretty damn brittle after 73k miles if you ask me. Glad I replaced that part.

[e92zero]

In the picture of the pumps, it looks like the vane of the GT4 is in the opposite direction of the other 2. Does that matter or the pictures are mirrored?

[admranger]

Originally Posted by dj_dub

Just because we haven't seen or heard any issues with the factory stock impellers/water pumps, doesn't mean they can't become an issue or either nobody has reported any on the interwebz. If I was already replacing the thermostat and temp sensor, IMO it's smart to change the water pump as well since you're already working in that area. Doesn't cost much and not too much added work involved...better safe than sorry.

After taking out my stock water pump, I placed it on my garage floor vertically and it lightly fell on it's side, the plastic impeller broke easily. It was pretty damn brittle after 73k miles if you ask me. Glad I replaced that part.

I'm the worst when it comes to the "while I'm in there" club. My wife is always surprised that a crate motor doesn't get dropped when I do an oil change.

If you're in that deep, you may as well replace the pump. I agree.

[Richbot]

If your pump falls on its side inside the engine bay you have already reached a point where pump durability had become irrelevant, and should probably grab a fire extinguisher

[GORDON.M3]

I just got my REIN pump. It says its Made in Germany.

BMW probably went with plastic impellers to keep the weight of the engine down.

The metal on this impeller is not as nice as the aluminum one from the GT4 pump but still very solid and smooth pump.

As you can see from the photos the impeller is quite rough and not as polished as the GT4 alu impeller. Still better than plastic!