Water pump

BMWZ4MC

BMWZ4MC

Lifer!
 Diving out of the sun
I’ve had a slowly worsening coolant leak for sometime. I presumed it was the expansion tank, but it’s become evident that the leak is from the front of the engine, with a few water drops deposited on the serpentine belt after driving the car and some rust on the pulleys.
I suspect the water pump is failing. My research suggests that the water pump used in the S54 Z3M and Z4M is unique, differing from that in the E46 M3 and from all other BMWs. It’s very difficult to find a replacement outside of the USA, where the price is 700-800 USD. Has anyone else had this problem and replaced the water pump?
Thanks.
 
I brought a BMW water pump some 3 or 4 years ago to replace mine as it was getting a bit noisy. Was expensive then, couple of hundred I think....but not hideous as it probably is now.
Edit - I honestly don't know if there is a difference so will amend.....I only plumbed for a BMW one at the time as it wasn't too much more expensive than pattern parts and using on track, suspected BMW would have the *best* or premium design compared to others so last longer / take the abuse better.....otherwise I would have gone pattern tbh.

I don't remember it being out the question to fit a pattern part but....that is stretching my memory tbh so can't say for sure.

Sure it's not a seal / pipe or something else that's causing the leak?
 
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I'm not an M-bod at all but I'm curious about having a different water pump so here's my idle take: Assuming the block is the same (I know there's power output differences but that'd be a huge jump), then the pump body must be the same. The only reason to then change anything about the pump would be either:

a) different flow rate so it's fitted with a bigger or smaller pulley

or

b) different longitudinal alignment of the ancillaries (so longer or shorter stem or, far easier, different shaped pulley.) That's easy to check as it makes the alternator etc different.

As an engineer, if it's either of these cases, I'd have the same pump and a different pulley (which I assume bolts on.)

As I say, I know nothing but I'd be all over making an E46 one work!

(Edit: should have googled it. The viscous fan sits differently. It seems to sit further out on the Z so some form of spacer would sort that.)
 
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I thought expensive water pumps were the preserve of models with the electric ones, but trust BMW to make it different to the E46 M3 and slap on some M tax as well. :(

Luckily mine is OK for now. 🤞
 
Thanks everyone. The E46 M3 water pump (which is readily available for not much money) has an additional hole in the body for the expansion tank connection, and a longer shaft. Someone on a US forum reported managing to fettle an E46 pump so that it worked in their S54-swapped E30. They had fitted a Z3M engine and tight clearances made the longer shaft a problem.
@AndyBeech until I drove it this week, the leak has been very slow and only when the system is pressurised, so I couldn’t identify the source. I assumed it was the expansion tank because BMW plastic is notorious for cracking over time. I’m presuming it’s the pump itself only because the leaking coolant leak is evident at the very front of the engine. I’ll run it again and see if it becomes more obvious.
@smorris_12 , if I had more time, I’d buy an E46 pump and make one good pump out of two. Unfortunately, I’ll be paying a mechanic to fix it. My usual mechanic in the UK would have been happy to make it work, but the attitudes of mechanics in Sydney are different.
@chris719 , was your pumping leaking and did you source the replacement from BMW?
@Mr Tidy , I know you’re the water pump expert from your N52 experience, I’m sure you can’t wait for the Z4M-specific pump to fail too!
 
BMWZ4MC said:
@Mr Tidy , I know you’re the water pump expert from your N52 experience, I’m sure you can’t wait for the Z4M-specific pump to fail too!
Click to expand...
Trust me, I'm really in no hurry!

But I'm still playing water pump roulette with my 330i daily as it has an N52. :rolleyes:
 
BMWZ4MC said:
Thanks everyone. The E46 M3 water pump (which is readily available for not much money) has an additional hole in the body for the expansion tank connection, and a longer shaft. Someone on a US forum reported managing to fettle an E46 pump so that it worked in their S54-swapped E30. They had fitted a Z3M engine and tight clearances made the longer shaft a problem.
@AndyBeech until I drove it this week, the leak has been very slow and only when the system is pressurised, so I couldn’t identify the source. I assumed it was the expansion tank because BMW plastic is notorious for cracking over time. I’m presuming it’s the pump itself only because the leaking coolant leak is evident at the very front of the engine. I’ll run it again and see if it becomes more obvious.
@smorris_12 , if I had more time, I’d buy an E46 pump and make one good pump out of two. Unfortunately, I’ll be paying a mechanic to fix it. My usual mechanic in the UK would have been happy to make it work, but the attitudes of mechanics in Sydney are different.
@chris719 , was your pumping leaking and did you source the replacement from BMW?
@Mr Tidy , I know you’re the water pump expert from your N52 experience, I’m sure you can’t wait for the Z4M-specific pump to fail too!
Click to expand...
Yes it was leaking and I bought an original Z4M S54 pump. I had dried coolant spray on the side of the airbox because it drips onto the belts and gets flung around. It was also making a strange whine on cold starts and low ambient temp operation.
 
chris719 said:
Yes it was leaking and I bought an original Z4M S54 pump. I had dried coolant spray on the side of the airbox because it drips onto the belts and gets flung around. It was also making a strange whine on cold starts and low ambient temp operation.
Click to expand...
I have a stripe of dried rusty coolant across the undersurface of the bonnet in line with the belts, and the lower, inboard surface of my GruppeM intake has a similar deposit.
I’ve not noticed the whine as yet, but it’s rarely been lower than 20C for the last six months. I’ll start it early in the morning now it’s autumn and listen for it.
 
BMWZ4MC said:
I have a stripe of dried rusty coolant across the undersurface of the bonnet in line with the belts, and the lower, inboard surface of my GruppeM intake has a similar deposit.
I’ve not noticed the whine as yet, but it’s rarely been lower than 20C for the last six months. I’ll start it early in the morning now it’s autumn and listen for it.
Click to expand...
Would the waterpump, being electric, run on start up, I thought the idea of it being electric is that it wouldn't operate until the engine reached a certain tempreture?
Only asking as I have a bit of a wine but it's constant, I'm hoping changing the aux belt pulleys sort it, and I'd like to start with the cheaper item first if you know what I mean
 
4play said:
Would the waterpump, being electric, run on start up, I thought the idea of it being electric is that it wouldn't operate until the engine reached a certain tempreture?
Only asking as I have a bit of a wine but it's constant, I'm hoping changing the aux belt pulleys sort it, and I'd like to start with the cheaper item first if you know what I mean
Click to expand...
It's not electric
 
Ive not used a M3 one on a Z4, but i used my spare Z4M one on an M3 (shipping time was the issue) .. plugged the hole and off she went.. I would have thought the reverse was also possible??
 
The M3 pump has a longer spindle, as well as a different location for the expansion tank pick up. I suspect that there are clearance problems. Otherwise, BMW would have likely used the M3 part.
The thread I read where a Z3M S54 had been transplanted into an E30 described rotating the E46 water pump to address the pick up but having major issues with clearance due to the addition spindle length.
OEM pumps are available ex-BMW Germany with a four week lead time for c 800 AUD including delivery and local taxes. That’s the route I’ll take if I can’t source one in Aus.
 
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