M54 Water Pump Failure

2264 Views 41 Replies 14 Participants Last post by Attacking Mid, 9 d ago

Attacking Mid

Discussion Starter · 16 d ago

This is from my E53, but posting here for the benefit of pre-LCI E83 owners. Based on my online research, this is not a widespread problem, so I don't think one needs to draw negative conclusions about Saleri WP's or composite impellers. However, it's just something to consider as a possibility if you have a strange overheating problem. A sheared WP impeller just doesn't jump to to the top of the troubleshooting list and I've read reports of multiple professionals failing to figure this out. With that said,... for your viewing pleasure:

Hood Automotive tire Motor vehicle Toy Automotive design

This WP only had 45K miles on it. The first symptom was inconsistent cabin heating, which I assumed to be a failing thermostat, so no urgency to fix. The second symptom was an upper radiator hose failure resulting in loss of coolant and brief overheating, so still no reason to suspect I had any other issues. Since I had to replace the upper hose, I decided it was a good time to replace that suspect thermostat and I put in a new ET for good measure. No more apparent cooling system issues for all the short trips I used it for (it's a backup vehicle, so doesn't see any long distance driving), except... the cabin heater still didn't work quite right which puzzled me.

I should have used Torque or similar to check actual coolant temps rather than relying on the heavily damped dash temp gauge, but again... I didn't suspect I had anything wrong. Out of nowhere, I got the ominous "ding" notifying me of high coolant temps. I had to abandon the vehicle a few miles from home to let it cool overnight. I was able to get it home the next morning just before overheating again. Thinking through all the symptoms, I suspected I had perhaps a blockage of some sort in the cooling system preventing flow. Turned out I was ALMOST right!

AM.

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applehugger

· #3 · 16 d ago

This is very interesting to see! I honestly have no idea how there is any debate about composite vs. metal impellers. I've read anecdotal stories about metal impellers exploding like this, but I strongly suspect that is related to manufacturing issues, potentially from low-quality Amazon/eBay specials. Composite/plastic was used in the manufacturing process because they are easier to balance than metal impellers. Easier balance = less cost. It's purely a cost cutting measure and they simply cannot be trusted to hold up long-term, in my opinion.

Did you have issues flushing the plastic shards out of the cooling system? I would be concerned that some of the smaller ones could get stuck in tiny coolant channels in the block or head, potentially causing coolant starvation issues.

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applehugger

· #6 · 16 d ago

FCP Euro has no control over of manufacturers if they switch production facilities and/or methods/materials. That may be what happened - I've read several threads about receiving Lemfoder parts that are made in China and clearly poorer quality than the German-made ones.

Any change you'd consider one with a metal impeller? FCP does sell a Graf unit that I used in my E46 which seemed to be very high quality. I personally wouldn't feel comfortable putting one with a composite impeller in any of my cars, and I'm surprised you're considering it after your recent experience.

I suspect you got lucky if most of the impeller came out in large chunks. I would have done the same thing - backflush everything. It's amazing how much stuff comes out of poorly maintained cooling systems - just did that on my E83.

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applehugger

· #20 · 15 d ago

I am actually quite curious to see what you receive from FCP Euro. This thread has made me wonder whether my mistrust of composite impellers made from the proper material is based more on myth than fact. However, I still maintain that a metal impeller is a better solution overall as you don't have to worry about one of those being made out of the wrong material.

I do know that some (all? early?) E36s came with plastic impellers that were properly unreliable, so BMW at some point switched to a composite material. It is hard to tell the difference between plastic/composite at a glance.

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applehugger

· #23 · 15 d ago

Attacking Mid said:
I can't recall the brand of metal-impellered pump I put in my E46 years ago, but I recall being a little disappointed when it failed after a shorter interval than I had hoped.

Out of curiosity, what was the mode of failure for the metal impeller water pump that you put in your E46?

FCP's customer service is amazing. They'll definitely be interested to hear from you and care about your experience. I really like that business.

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applehugger

· #28 · 15 d ago

Haha I don't think so. What is a FLAPS pump?

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applehugger

· #32 · 15 d ago

Oh, Doug must be commenting. There’s an ignore button. It greatly improved my Bimmerfest experience 🤣

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applehugger

· #34 · 15 d ago

frisbeeguy said:
Lol. That explains why you didn’t see his post directed to u. I get it now!

Blissfully unaware

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