Z3 Water pump failure-Fact or Fiction

The car has run like a clock, and maintained.
58,865 miles bang water pump failure. Broken belts and a little damage to fan shroud.

I hadn't seen this thread until today when it was revived, but I just discovered that mine was weeping yesterday at 68K miles.

I have been chasing down a very slight coolant loss for a couple of years now, replaced a leaking expansion tank cap and a thermostat that was leaking and not allowing the car to warm up completely (electronic, leaking at the connector) when I first got the car at 48K.

I kept having to add a very slight amount of coolant every 3-4 months and for the life of me couldn't find the source of the leak. Finally smelled coolant at the front of the engine after a run yesterday and it finally leaked enough for me to pinpoint it to the water pump bearing based on the white film around the area.

Because this is a common occurence I religiously check the fan for wobble whenever I'm fooling around under the hood and it is still very solid, no play at all. Lucklily I was planning a coolant change this week anyway and I have a new pump on hand since I was expecting this sooner or later.

Moral of the story: Make stock water pump replacement a standard 60K maintenance item, and I'm thinking that 90K will be my interval for radiator, expansion tank and hose replacement unless it rears its head sooner.

ETA: Fan nut was on VERY tightly, cracked the pulley trying to remove it by wedging a screwdriver between the pulley bolts, too much flex in the screwdriver shaft to work effectively, fabricated a pulley holder and got it off after 3-4 sharp whacks with a hammer, replaced with an aluminum pulley from eBay ($28 shipped). My OEM pump had the metal impeller. That model pump has a reputation for pump bearings wearing quickly and I did find a slight amount of play in the bearings once I had the fan off, replaced with OEM pump w/composite impeller. Had a noisy belt tensioner bearing as well so replaced the tensioners and belts while I was in there.

Don't wait for the inevitable.
Mine went @ 65K kilometers.
This is a Weekender, so I noticed a small amount of coolant in the engine bay being spread out over the hood lining.
I knew about the problems these cars had with water pumps.
So I purchased everything I needed.
Stewart Pump, hoses, thermostat, belts & of course coolant.
I put aside the Saturday after I received all the parts to do the install.
The friday before that, it was a glorious day, so I took her out for a spin. 1 block away from home the pump bearing disintergrated.
Took out my fan, fan shroud, & rad., but fortunately not the hood.
I was without the car for about a week, while I waited on the additional items to be delivered.
The whole operation of removing the old and replacing it with new, took me about 3 hours.
So a word from the wise, If the boys on these and other forums say change the pump around 60K then do so.
Mine is a 2001 3.0 roadster, it is 10 years old. only 65K kilometers.
This spring it's Lube time. Tranny, Diff, Brake fluid and Power steering fluid flush time.

BTW If you are going to get into the front of the engine, then do the Thermostat, hoses & belts as well.
It's good insurance, and easy to do while working there.

Just my 2cents.

Mine is a 2002 2.5 roaster Impala Brown-copper-metallic-bronze with two tone leather tab and black interior.

Thanks Wm Wolfe. LoL not Am oh well.

The biggest reason for the premptive replacement is that the aluminum engine block
can not stand even a small amount of over heating. Anytime you seen the temp past midline
shut it down and find out why. The rest is cheap insurance.

stewart water pump (though bosch is 1/3rd the price)
thermostat and enclosure (stayed with a new phenolic)
hoses and serpentine belt
radiator with expansion tank
all in all $450 parts but with bosch components around 300
I thought the stewart pump wasn't worth the 3x price.
car is beautiful. and 15 years old.
Jay Lo

would eliminating the mechanical fan help preserve water pumps by stressing them less?

the mech fan has a job to do and it is pretty good at it. i have seen a kit to eliminate the electrically operated fan on newer models but again since overheating is so dangerous on these cars why take the risk? maintenence is the price you pay when you spend $7,000 for a car instead of 70.
j-lo

" maintenence is the price you pay when you spend $7,000 for a car instead of 70."


i like your logic.

but i don't understand why someone would want to eliminate the electric fan. often, people like to eliminate the mechanical fans because it means more power and less stress on the waterpump. i haven't run across anyone doing it on the list. i'll keep researching the archive.

Replacing all the hoses, belts , thermostat, fan, shroud, pump, with BMW parts about $570.00
. Best to start checking at 50k miles, or just replace it then.

Surprised that bearings would fail that soon. With BMW knowing the damage it can cause.
I am lucky the radiator did not get damaged.

Wm Wolfe

Honestly, once you get the fan out the first time, then the rest is pretty easy.

You don't absolutely need to replace everything.

Just spring for the pump and put in a new thermostat and replace the other crap when you feel like it.

The pump will fail before 75k miles.

The pump failure is surprising reliable, its happened to me twice between 62 and 72 on different cars.

I am trying to decide what fan to go with on the S54 at the moment.

I figure the fan is a big part of why the pump fails.

Originally Posted by Mpire

Honestly, once you get the fan out the first time, then the rest is pretty easy.

You don't absolutely need to replace everything.

Just spring for the pump and put in a new thermostat and replace the other crap when you feel like it.

The pump will fail before 75k miles.

The pump failure is surprising reliable, its happened to me twice between 62 and 72 on different cars.

I am trying to decide what fan to go with on the S54 at the moment.

I figure the fan is a big part of why the pump fails.

Mpire, any reason you're not doing the fan delete mod? I've been debating going this route on my M54.

"fan delete mod" that's the term i was looking for. it makes using the archives sooo much easier.

is the current electric fan wired to come on at a certain temperature or only when the a/c is on? here is a company with parts:

http://www.understeer.com/onlinestore-engine.shtml

Originally Posted by BlackjackM

Mpire, any reason you're not doing the fan delete mod? I've been debating going this route on my M54.

I wasn't saying not to do the fan delete, I was simply implying that I would replace the water pump and thermostat before they explode, which they absolutely will.

The hardest part by far is getting the mechanical fan off. The rest of the work is surprisingly easy to do and will take about an hour plus any applicable cleaning and detailing time.

It took me longer to bleed the cooling system than everything else combined.

The fan delete is a good idea though, no reason not to do it, but get the water pump done or it will go boom.

Originally Posted by Mpire

I wasn't saying not to do the fan delete, I was simply implying that I would replace the water pump and thermostat before they explode, which they absolutely will.

The hardest part by far is getting the mechanical fan off. The rest of the work is surprisingly easy to do and will take about an hour plus any applicable cleaning and detailing time.
eyeing the
It took me longer to bleed the cooling system than everything else combined.

The fan delete is a good idea though, no reason not to do it, but get the water pump done or it will go boom.

I see, when you mentioned you were debating which fan to go with I inferred that you were keeping the mechanical one.

Originally Posted by BlackjackM

I see, when you mentioned you were debating which fan to go with I inferred that you were keeping the mechanical one.

I bought a brand new fan for the Z3, but ended up selling it to wertles for his rebuild and went with the electric fan instead.

Its just preventative maintenance I guess. But the real reason that I did that is because the hardest part by far is removing the mechanical fan, the rest is a piece of cake.

So if I ever have to do any more maintenance, I can easily yank it apart to get to it.

You can always do the fan later, or just about everything else later.

The fan may or may not explode, but the water pump will sure as hell blow all to hell before 70k miles.

My 98 Z3 has 102k miles so Im probably running on borrowed time.
My part of CA gets up to and over 100 degrees, sometimes 110 degrees. I wouldnt remove the electric fan unless I lived in Alaska!
Time to order a new coolant pump...

Originally Posted by Captain Roundel

My 98 Z3 has 102k miles so Im probably running on borrowed time.
My part of CA gets up to and over 100 degrees, sometimes 110 degrees. I wouldnt remove the electric fan unless I lived in Alaska!
Time to order a new coolant pump...

If you are going to change the pump, don't mess around, get a Stewart pump.
And since you are going to remove the fan, shroud....etc, change the Thermostat and both belts as well. I also changed the Fan Clutch.
No point in having to get back in there for a minor item that could have been changed when you were there.
One other thing, when my pump bearing blew up, I cracked the pump pulley when I removed the fan.
It's plastic, I replaced it and the plastic power steering pulley with aluminum ones.
But that is up to you to decide.

Changed my pump and thermo right at 60,0012. Upper hose was almost gone, lower was fine. The old pump had been changed already I think - it has a metal impeller, but since I have no service records I dont know when or who did it. I went with a Stewart. I tried an all metal thermostat housing ( M52TU engine, so its the electric one). No good, weeping leak thru the electrical connection. Went and got a new BMW plastic one. I guess I can relax until 90-100K when the radiator will be done. For me, thats about a year, since I do 500 miles a week as a DD.

Originally Posted by BlackjackM

I see, when you mentioned you were debating which fan to go with I inferred that you were keeping the mechanical one.

You just have to think left handed when removing the fan. NBD.....
Do it once & you can get a pit job in Nekcar....

My daughter has a 1997 Z3 that I try to do the repair work on for her. I have a coolant leak that appears to be coming from the area near the water pump but I can't quite detect exactly where it is coming from. Does the water pump have a weep hole on it where coolant can leak out when the seals go bad as in cars I am accustomed to working on in years past?

Originally Posted by Randy Fancher

...
Does the water pump have a weep hole on it where coolant can leak out when the seals go bad as in cars I am accustomed to working on in years past?

Yes.

But the rest of this thread is correct - BMW cooling systems are problematic. Water pumps and thermostats should be replaced every 60k, and radiators and expansion tanks every 100k (at which point you might as well replace the hoses).

The 4 cyl cars also have two plastic cooling connectors which will crack. See http://www.318ti.org/forum/showthread.php?t=18066 for a 4 cyl cooling system rebuild.

Unless you know when the cooling system was last rebuilt, you should do a complete cooling system rebuild.

Originally Posted by kostverloren

Only way to go for full confidence.

http://www.turnermotorsport.com/html...gn=STE%2030330

The Stewart Water Pump is $175 at Bimmerzone. I recently purchased & installed one on my 3.0 '01 Roadster. Ask for Vincent...the manager. Tell him Morris Chance sent you...

Everyone seems to have a favorite pump for their 6 cyls, is there a preferred pump for a 1998 1.9, and is the need to replace at 60k as real? I just acquired one with 68k.

Originally Posted by wrench13

Changed my pump and thermo right at 60,0012. Upper hose was almost gone, lower was fine. The old pump had been changed already I think - it has a metal impeller, but since I have no service records I dont know when or who did it. I went with a Stewart. I tried an all metal thermostat housing ( M52TU engine, so its the electric one). No good, weeping leak thru the electrical connection. Went and got a new BMW plastic one. I guess I can relax until 90-100K when the radiator will be done. For me, thats about a year, since I do 500 miles a week as a DD.

My cooling system has been replaced...all started with signs of white residue around top side of radiator. Then I discovered a leak around the neck of the radiator where the drain plug is located....cracked neck. I replaced the BMW (Valeo brand) radiator with another one. Afterall, it has lasted 11 years so I figured this one will last as long. Since the car had 63,900 miles, I replaced the water pump with Stewart pump, BMW plastic thermostat housing, both belts, upper/lower hoses, hose between radiator & expansion tank....total cost for parts including new coolant was $650. Of course, I did all the labor....saving hundreds of $$. CAUTION: Make sure to follow proper draining/replacing coolant procedures. You don't want any bubbles in the system.

Originally Posted by CTHuskyinMA

Everyone seems to have a favorite pump for their 6 cyls, is there a preferred pump for a 1998 1.9, and is the need to replace at 60k as real? I just acquired one with 68k.

Yes, the need is as real. The M44's aluminum block has a very small tolerance to being overheated. Consider the cost as insurance.

Unfortunately the Stewart pump isn't available for the M44. I would go with a stock BMW waterpump.