Some time back my father commented that friends of his no longer drove Mercedes due to continually suffering faulty water pumps. I replied that I was not aware of this being a real issue. Yes, I had replaced mine in my '73 350SLC a couple of times in the 22 years I have owned it, but I did not consider this unreasonable after around maybe 350,000km. As far as I am aware the pump in our '90 300TE is still the original at over 180,000km and my 190E had one replaced by the PO shortly before I purchased it at around 210,000km.

Not long after, the pump in my father's '93 E320 (W124 M104) at around 130,000km started leaking and I had to replace it earlier this year. My parents have just returned from a long trip in their '96 E230 (W210 M111) complaining of a rumbling noise from the front of the engine. I fixed it yesterday. You guessed it, another water pump. This one in a car that has travelled less than 120,000km that they have owned from new. All the cars have either been dealer serviced or I have more recently maintained and genuine MB coolant has always been used. My father is now convinced that MB water pumps are rubbish and I am losing confidence. Incidently, in each instance I have fitted a Laso brand pump as a replacement. For the M104 it was little more than half the price of genuine and for the M111 it was only one third the price of genuine.

What are the water pump experiences of others here?

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107.023: 350SLC, 3-speed auto, icon gold, parchment MBtex (sold 2012 after 29 years ownership).
107.026: 500SLC, 4-speed auto, thistle green, green velour.
124.090: 300TE, 4-speed auto, arctic white, cream-beige MBtex.
201.028: 190E 2.3 Sportline, 5-speed manual, arctic white, blue leather.
201.028: 190E 2.3, 4-speed auto, blue-black, grey MBtex.
201.034: 190E 2.3-16, 5-speed manual, blue-black, black leather.

Hello,
I find that the average lfe of any manufacturer's pumps can vary dramatically.
I have replace the BMW M30 w/p with boring regularity, average of three years on every car(3.0,525&635).
On Volvo 240, it has been done every 6 years or so and on an Opel Manta A, the pump would expire every 2-3 years.
Mercedes has been longer lived, the W124 260E pump ran to 180,000 miles(and 15 years) before the o-ring sprang a leak, BUt due to the difficulty in R&R, a new Laso pump was fitted, W115 200 original pump replaced after 27 years and unknown mileage(had to knock it out with a hammer!), the vanes were worn down and the thing was rattling, but only replaced when it began spewing coolant onto the road.
Having said that, the 260 will probably spring a leak this evening.................
Have a good week.

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Nachi11744

Interesting complaints.

If you check the longevity of water pumps on the domestic counterparts, you will find that many have failures much earlier than the cycles you or your father have experienced.

I replaced one on two Chevys I owned (consecutively), and neither had reached 60,000 miles...and a water pump went on my Dad's Buick at 70K!

I haven't noticed any unusual failure rate on any of my MBs...but then again, only the W124 has surpassed the 100K mark...and I replaced the water pump on that one at 120K...

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car

8 Mercedes
250,000km lapel pin due to driving Mercedes 250,000km+.

ZERO water pump replacements.

Always use Mercedes antifreeze, always make sure the belt tension is correct.

Dave

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1970 220D, owned 1980-1990
1980 240D, owned 1990-1992
1982 300TD, owned 1992-1993
1986 300SDL, owned 1993-2004
1999 E300, owned 1999-2003
1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD
1988 560SL, 100,000mi, owned since 1995
1965 Mustang Fastback Mileage Unknown(My sons)
1983 240D, 176,000mi (My daughers) owned since 2004
2007 Honda Accord EX-L I4 auto, the new daily driver
1985 300D 264,000mi Son's new daily driver.(sold)
2008 Hyundai Tiberon. Daughters new car

It seems that the early models possibly had longer lived pumps. Is this another case of a drop in quality in recent years? In my case, the newer the car, the shorter the life of the pump. Yes they have all been used only with genuine MB coolant and belt tension is assured by the automatic tensioner for the poly V belt.

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107.023: 350SLC, 3-speed auto, icon gold, parchment MBtex (sold 2012 after 29 years ownership).
107.026: 500SLC, 4-speed auto, thistle green, green velour.
124.090: 300TE, 4-speed auto, arctic white, cream-beige MBtex.
201.028: 190E 2.3 Sportline, 5-speed manual, arctic white, blue leather.
201.028: 190E 2.3, 4-speed auto, blue-black, grey MBtex.
201.034: 190E 2.3-16, 5-speed manual, blue-black, black leather.

I am also starting to see the effects of proper operating temperature on MBZ water pumps. If you let your engine get too hot for too long .... look for a water pump replacement not too far behind. (Don't ask me how I know this .... geesh!)

Haasman

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'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)

While I would doubt that I would consider my MB unworthy, or any make of car for that matter, as a result of premature waterpump failures! I do wonder why now what would be the life expectancy of a waterpump?

A waterpump is mechanically simple consisting of a body, a shaft with metal centrifugal impeller, sealed bearing, and a synthetic rubber seal. There is little to ware out.

I have replaced maybe 10 waterpumps in my lifetime and all of those pumps wore out the shaft seal and leaked coolant out the provided drip hole or tube, but only after many years, and many miles!

The only other likely item to ware out or fail would be the sealed bearings, although I have read somewhere about the metal of the impeller corroded to the point it could no longer push coolant.

So what wares out, and why?

The sealed bearings cannot be breached unless the water seals ware to the point of allowing water to enter the bearings and they are sealed as well, and by that time you would have replaced the pump because it was leaking out the drain anyway, right?

So bearing are probably least amongst causes, but could ware out prematurely by not having proper lubrication, or of inferior quality ball bearings (made in India, for example) It seems that the most likely cause for water pump failure is routed around the synthetic rubber water seal resulting from either poor design, or lack of quality of the synthetic rubber material.

Makers of most all anti-freeze claim lubricating qualities, incorporated in their product, also included are anti-corrosion addatives, anti-leak, safe for aluminum, etc.

It would seem there is no pattern to waterpump life, but for example, there is a wide spread between say one's 300E waterpump failing at 50K and anothers 380SL waterpump failing at 225K. If MB uses the same builder for all it's waterpumps, one could assume quality of the componant parts for all pumps to be the same, except for their shape and size applicable to different models of MB engines.

In my opinion, it boils down to the level of quality of the materials used. For example, the builder of MB's water pumps may buy ball bearings next month from China, and maybe a different synthetic rubber seal from Mexico, or maybe Ugoslavia!

A long read, but any comments?

Steve....................

Seals are by far the most common cause of water pump failures.

Consider that a coolant pump seal serves a pretty critical purpose from a design standpoint...maintaining a hydro-dynamic seal against a turbulent high-pressure variable temperature chemical solution for millions of cycles! It's amazing that it works at all!

The "ultimate" seal has befuddled engineers for years! Even NASA had some trouble with o-ring seals (remember Challenger? ).

Less of an issue is impeller design, but anyone who has read a textbook on fluid mechanics is all too familiar of how cavitation can eat rotating vanes in an alarming rate! Blade design cures this, but cheap materials or lackluster quality control can create a failure here.

Finally, plain disregard for the use of proper coolant creates corrosion problems for the pump...and the rest of the cooling system components!

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car

May have been a coincidence but here is what happened to my 1991 300CE.

Aug '03 at 122m, thermostat failed and the car overheated. Limped home by pulling over frequently.

Oct '03 at 124m, oil in the coolant resevoir, so new head gasket. Driving the car home from the indie, there was catastrophic water pump failure. From what I can tell from the service records, this was the original water pump with only a pulley being replaced at 87m.

Relatedly, my 1990 Lexus LS400, had it's first new water pump at 127m in '03.

A friends 2000 VW Jetta just had a new water pump at 35m. This car has a 10 year 100m water pump warranty! Only problem was that the aux water pump was also leaking but not covered, $350 to replace.

glenmore
1991 300CE
1990 LS400

Don't most auto makers suggest replacing timing belts at around 70k miles. And I also seem to recall that every mechanic I've ever had replace one also recommended replacing the water pump while replacing the timing belt.

I don't think 120k miles is an unreasonable life cycle on a part that does what a water pump does.

I would imagine that you could also attribute a shorter water pump life to belts that are too tight. It would put undue stress on the seals in the pump and cause them to wear out faster.

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'84 300CD Turbo 132k (Anthracite Grey) - WVO - My daily driver - Recently named coo-coo-coupe by my daughter.
'84 300D Turbo 240k (Anthracite Grey) - Garage Queen
'83 300D Turbo 220k (Orient Red) - WVO - Wifes daily driver

I'm not a certified mechanic, but I did stay at a HolidayInn Express last night.

James:

Replacing the pump and belt together is something one does on a transverse-mounted engine, such as those in Honda Accords, Civics.

Done a bunch of those.

Newer MBs may have such a design. Don't know - I drive an older one.

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Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"

We own three MB's and I don't think I have replaced any part "prematurely". I really believe that MB made all older cars to really run a long time. We did have the waterpump replaced on our '93 300TE 4Matic at about 240M, it did not give any indication of getting ready "to go", but we drive that car on annual trips into some really remote areas and a waterpump failure and replacement could really be an inconvenience. The first problem would be to get someone to find us. We carry a GPS. So at 240M I felt we probably had the better part of that pumps life cycle. I have never used MB antifreeze, but do change a name brand every couple of years.
We have looked at buying a new MB but the tremendous array of "gadgets" frightens me. Too bad they won't make a "simple" MB car.

Roy

'82 SL 140M miles
'83 240D 240M miles
'93 300TE 4Matic 255M miles
All cars in excellent condition and still going strong, no engine work, minor oil leak in '93 and a little 4Matic work.

Well as it was explained to me.. and it makes sense. Many engines the water pump is physically located underneath the timing belt. So might as well replace it while the belt is off to save on the labor. Especially since murphy makes sure if you don't the water pump fails shortly after the belt was replaced.

I guess my point is that a water pump that lasts 120k-200+k is outstanding.

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'84 300CD Turbo 132k (Anthracite Grey) - WVO - My daily driver - Recently named coo-coo-coupe by my daughter.
'84 300D Turbo 240k (Anthracite Grey) - Garage Queen
'83 300D Turbo 220k (Orient Red) - WVO - Wifes daily driver

I'm not a certified mechanic, but I did stay at a HolidayInn Express last night.

We did not buy our 300TE 4Matic new but we have put the vast majority of the 255M miles on it. So I can't vouch for the fact that the pump was "original". Our independent repair man was the one who suggested we replace the pump, even though it was not giving any signs of trouble, since he felt it had over run its expected life time. We are conservative in maintaining our cars and opt to change a part before it breaks down. He did replace the pump with an MB, since he says he can get a good warranty from them, where he might not from a "look alike" manufactured pump. He said it was an all day job to make the change, since there is a lot of stuff that is connected up in that area. I have confidence in him and took him at his word. His shop does a great deal of MB work and at least one of his men specializes in MB repairs.

Our other two MB's have original water pumps and they have a bit of mileage on them. I think the 240D has only had an alternator replaced, or re-built, I think, also the AC compressor, but the SL has only had a fuel pump relay and that is just recent. But that will surely shut you down.

This is a really interesing MB link, thanks for all the cooperation. Roy
'82 380SL
'83 240D
'93 300TE 4Matic

I have owned around 15 cars over the years and have generally replaced the water pump on an average, about every 60K miles. My 1977 Toyota Celica (20R engine) needed two: one at 80K and another at 165K.

I have replaced a number of water pumps in friends' cars, but always with RWD old-stlye engines, which is an easier chore.

I have not replaced the water pump in either of my Mercedes. Perhaps I should not publically announce this, lest Murphy hear me.

The cause is always the same: the seal leaks where the shaft goes through the body of the pump. I have yet to see a water pump with ball bearings.

I have found that one can of anti-freeze restorer/water pump lubricant (Solder Seal brand in the yellow can, at under $2.50) seems to prolong the water pump and prevents any rust in the coolant.

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Semibodacious Transmogrifications a Specialty

1990 300D 2.5 Turbo sedan 171K (Rudolf)
1985 300D Turbo TD Wagon 219K (Remuda)

"Time flies like and arrow, yet fruit flies like a banana"
---Marx (Groucho)