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Old 08-01-2017, 11:34 AM   #1
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Composite or metal water pump impellers?

Hi guys,

Long story short, water pump failed on my 2004 S and I ordered a new one along with thermostat, belt, pulley, gaskets etc. Only thing is.. a metal impeller pump arrived this morning despite me requesting a composite one on my order.

Opinions on what to do? Send it back or use it?
I'm aware of some of the pros and cons of both.

Thanks.
Ken.

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Last edited by itskenallen; 08-01-2017 at 06:17 PM.
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Old 08-01-2017, 11:54 AM   #2
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If you're aware of the pros and cons of both why are you asking?

I'd go for composite
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Old 08-01-2017, 12:13 PM   #3
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+1 on clickman's thoughts
You know your own answer because you ordered a composite impeller WP in the first place
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Old 08-01-2017, 12:45 PM   #4
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ime - The main objection to a metal impeller is that when the bearing fails it will excavate the w/p housing in the crankcase half. A diligent operator would routinely check the bearing and replace the w/p proactively after about 50-70k miles*Search for more details). It is easy and quick to check the w/p bearing.
The plastic impeller mode of failure is disintegration .The fragments can lodge and block flow anywhere in the cooling system.Good luck finding them. How would you know some vanes have broken? Maybe a cooling problem.Maybe not. Routine replacement may or may not be soon enough to avoid the problem.
There is way more in Search -many more pros/cons
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Old 08-01-2017, 01:17 PM   #5
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Originally Posted by itskenallen View Post
Hi guys,

Long story short, water pump failed on my 2004 S and I ordered a new one along with thermostat, belt, pulley, gaskets etc. Only thing is.. a metal impeller pump arrived this morning despite me requesting a composite one on my order.

Opinions on what to do? Send it back or use it?
I'm aware of the pros and cons of both.

Thanks.
Ken.

Sent from my Galaxy S8+ using Tapatalk
Get the composite impeller pump.
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Old 08-01-2017, 03:26 PM   #6
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If you're aware of the pros and cons of both why are you asking?

I'd go for composite
I'm interested in the opinions of professional people like Pelican etc.

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Old 08-01-2017, 03:28 PM   #7
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Get the composite impeller pump.
Could u elaborate on this a bit please?
The pump I received is manufactured by GEBA and apparently has uprated bearings.

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Old 08-01-2017, 04:53 PM   #8
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Uh, Pelican is not a mechanic, they are a parts vendor

Get a Pierburg WP. Its the same as a a factory one, but less $$
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Old 08-01-2017, 05:23 PM   #9
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Uh, Pelican is not a mechanic, they are a parts vendor

Get a Pierburg WP. Its the same as a a factory one, but less $$
Um... What?
Pelican do some of the best maintenance and diy guides available today. Wayne Dempsey is a genius and well knows the Porsche engines.

I respect JFP's advice but the reason I'm asking the question is that Nick @Pelican parts says on the 986 guide that he prefers the plastic impellers, yet on the 997 guide he recommends using the metal impeller version. My father has a 997 and is replacing his also, hence how we came across this.

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Old 08-01-2017, 06:13 PM   #10
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Could u elaborate on this a bit please?
The pump I received is manufactured by GEBA and apparently has uprated bearings.

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When the bearings go bad in these water pumps, and they all will go bad regardless of who makes the pump, the shaft starts to move side to side resulting in the impeller hitting the front of the engine case. With a composite impeller, the impeller breaks up, which can cause cooling system blockage if you don't flush all the bits out. If the impeller is metal, it starts machining away the engine case, which also fills the cooling system with fine metal which is a royal pain to get out, but it also permanently enlarges the clearance between the pump impeller and engine case, resulting in permanently reduced coolant flow regardless of which type of pump is used, and ongoing cooling issues.
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Old 08-01-2017, 06:14 PM   #11
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Um... What?
Pelican do some of the best maintenance and diy guides available today.

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I'm afraid I cannot agree with those statements.
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Old 08-01-2017, 06:19 PM   #12
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I'm afraid I cannot agree with those statements.
Fair enough. Thanks for your info above.
I've seen mixed recommendations, that's why I created the thread... To get opinions of experts.

What's your opinion on the thoughts of the metal impeller version having uprated bearings and therefore possibly outlasting the engine ?

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Old 08-01-2017, 06:28 PM   #13
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Here is a real world data point from a metal impeller heretic. I changed the original water pump in my 03 S about 4 years ago at around 42,000 miles and had one with a metal impeller installed. This May at about 66,000 miles the bearing started to fail on that water pump. When the bearing failed, it started leaking and the light in the temperature gauge started blinking. The air temperature was in the 90's and the water temperature on the gauge stayed just above 180. I drove home about 50 miles and then had it flat towed to my Indy specialist. He said that he'd never seen a water pump fail that quickly, and his parts supplier replaced the pump for free under warranty. He also uses the same metal impeller water pump in his 987 Cayman S with a 3.8 liter engine. My point is that in this instance, there was a clear indication that I had a problem and it was addressed well before the impeller came in contact with the engine block. The thing about a composite impeller is that pieces of the impeller blades can break off before the water pump bearing fails, those pieces can lodge in the heads and cause hot spots and cracks in the heads. That will happen at some point due to the impact of heating and cooling cycles. Either metal or composite, they both need to be replaced proactively.

I love my car, and I'll be the first to say that Porsche got the vast majority of things right with it. But keep in mind the composite impeller water pump is brought to you by the same people who brought you the IMSB, headlights with lenses that melt, sticky black interior plastic and glued in GT 3 cooling system fittings that fail.
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Old 08-01-2017, 07:18 PM   #14
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Fair enough. Thanks for your info above.
I've seen mixed recommendations, that's why I created the thread... To get opinions of experts.

What's your opinion on the thoughts of the metal impeller version having uprated bearings and therefore possibly outlasting the engine ?

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That kind of a statement from a vendor is pure BS sales crap. How do they know how long an engine may last? What information do they provide about their uprated bearing?

Besides you didn't want this WP to begin with. Get the one you wanted and you'll be good to go.

Heck, saying "my water pump will outlast the engine" on our cars may not necessarily be that much a statement!
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Old 08-01-2017, 07:26 PM   #15
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I'm interested in the opinions of professional people
Say that up front so "amateurs" like me don't waste your time. Because, unfortunately, that's what most of the people on this forum are...
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Old 08-01-2017, 07:53 PM   #16
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That kind of a statement from a vendor is pure BS sales crap. How do they know how long an engine may last? What information do they provide about their uprated bearing?

Besides you didn't want this WP to begin with. Get the one you wanted and you'll be good to go.

Heck, saying "my water pump will outlast the engine" on our cars may not necessarily be that much a statement!
Yeah very true. They provide no info whatsoever on the bearing specs.
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Say that up front so "amateurs" like me don't waste your time. Because, unfortunately, that's what most of the people on this forum are...
Dude I consider most people on here as professionals. Whether mechanics or not, lots on here have years of experience in cars in general, and esp these waterpumps in particular.

U seem to have a chip on your shoulder or something as both ur comments have been sarcastic. I am purely trying to expand my knowledge base to help me decide what to do.

I guess what I was really looking for in creating this thread was the hope that people might tell me that the metal version will be fine and no need to delay getting my car back on the road for another week or two by returning it etc etc etc. I was undecided what to earlier and now I'm fairly sure I'll be returning it and waiting for the composite.

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Old 08-01-2017, 07:58 PM   #17
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I'll be scrapping the engine that this pump came out of, or selling it cheap to someone who wants to part it or rebuild. Pieces of the composite impeller are somewhere in the engine and not coming out. Driven hard, it dumps coolant, then overheats (The cooling system has been replaced/tested).

Metal or composite? I don't care. Replace them about every 3 years and they should be fine. Wait 'till a failure and you can get bad results with either.

Pierburg makes good pumps, so does Geba, most forum members who are into this stuff will recommend the Pierburg.

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By the time it makes noise or leaks it may have already shed plastic impeller debris that can end up in the cylinder heads.. While the majority of the failures that we see with cracked heads come from the 2000-01 engines we have seen this happen to engines as late a 2006. No matter mileage we change water pumps every 3 years, whether or not the engine is running the plastic impeller blades are exposed to coolant.

The metal impeller blades may not fail, BUT if you have a pump bearing failure the impeller "machines" the aluminum housing away and destroys the engine. Water pumps are cheap and easy to replace.
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https://rennlist.com/forums/996-forum/666866-update-thoughts-on-preventative-water-pump-replacement-79k-my-03-a.html#post9051269

Use gt3 water pump with metal impeller?
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Old 08-01-2017, 08:06 PM   #18
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I'll be scrapping the engine that this pump came out of, or selling it cheap to someone who wants to part it or rebuild. Pieces of the composite impeller are somewhere in the engine and not coming out. Driven hard, it dumps coolant, then overheats (The cooling system has been replaced/tested).

Metal or composite? I don't care. Replace them about every 3 years and they should be fine. Wait 'till a failure and you can get bad results with either.

Pierburg makes good pumps, so does Geba, most forum members who are into this stuff will recommend the Pierburg.


https://rennlist.com/forums/996-forum/666866-update-thoughts-on-preventative-water-pump-replacement-79k-my-03-a.html#post9051269

Use gt3 water pump with metal impeller?
Thanks for this.. Some good info there.

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Old 08-01-2017, 08:35 PM   #19
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Originally Posted by itskenallen View Post
Hi guys,

Long story short, water pump failed on my 2004 S and I ordered a new one along with thermostat, belt, pulley, gaskets etc. Only thing is.. a metal impeller pump arrived this morning despite me requesting a composite one on my order.

Opinions on what to do? Send it back or use it?
I'm aware of some of the pros and cons of both.

Thanks.
Ken.

Sent from my Galaxy S8+ using Tapatalk
Kenallen how many miles on your 04 WP?
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Old 08-01-2017, 08:55 PM   #20
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Kenallen how many miles on your 04 WP?
I'm not sure exactly. There's a receipt from when it was replaced but no mileage recorded.

**Edit** It was recorded alright.. I just missed it. There's 20k mls (4yrs) on that failed pump. Not sure what brand it is till I remove it.

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