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Water pump lifespan question.

10K views 46 replies 10 participants last post by  Alter 
#1 ·
Fellows, please advise!

I'm ready for cooling system flush and overhaul. Nothing is leaking yet, nothing overheats. Hoses are in mediocre condition, have few damages, coolant is sort of ok, was changed before by previous owner, correct coolant (not the geen one :) ) Fan clutch works fine. Thermostat works ok, but is probably due for replacement (22y old).

So, what is typical pump lifespan? Hight quality aftermarket (Graf) is $71 not expensive, clutch is $120 (german made), i already replaced junction tee and have all other hoses and thermostat ready. Should i do preventive for pump and the clutch? Or leave them alone for another 20k?

Car has 51k and 22y old.
 
#2 ·
I would be more concerned about thermostat than water pump.

Water pump has cast impeller and pretty rugged construction. They usually develop leaks and that is a 'soft failure' mode.

Thermostats can get stuck and this is a much 'harder' failure mode that can have more catastrophic consequences.

For longevity of service on both of these items it is prudent to use only mfr recommended coolant. On these aluminum block motors I always use only veh mfr coolant mixed with distilled water and change at 2 yrs max regardless of mileage.

That's cheap insurance.

My W140 has late M119 motor. New (factory rebuilt) MB pump is about $200. I am wary of aftermkt on pump or thermostat. It looks like MB is rebuilding both M119 pumps.

If you really felt you wanted to replace the pump, then you might want to consider that, but definitely replace the thermostat. Replacement of thermostat on M119 is a bit of a knuckle-buster with the short bypass hose.

Pump is either 119-200-1501 or 119-200-2101
 
#3 · (Edited)
In my car the fluid is original and seems to be clean, it also looks like couple hoses have been changed (look better then the others). So, coolant was probably changed too. Pump pulley rotates well and silent, without belt (by hand).
So, if you are saying that water pumps are usually "soft fail" i could probably do just the thermostat, hoses, thermostat gasket? And coolant of cause.
Should i do preventive on fan clutch? Clutch seems to be original. Clutch is working fine at the moment.
 
#4 ·
1.) If it ain't broke, don't fix it.

2.) Hoses and a thermostat should be all that are necessary, along with MB branded (blue) coolant. Also replace the "quadruple tee" on the firewall if you car is so equipped, as these will fail due to age and when doing so, do it catastrophically. Buy OE ONLY - DO NOT BUY A URO BRAND TEE!

No gasket on the thermostat - just a big "O" ring that will come with the thermostat. Use anti-seize on the bolts and don't over torque them or they'll break off. Water pumps in these cars are not prone to failure. Thermostats tend to fail or stop working properly in a relatively short period of time. Be sure to buy a quality one (Behr or Wahler). Fan clutches can wear out with age, but unless you're seeing evidence of the fan not cooling properly at low speeds or at stops, don't worry about it.

Dan
 
#6 ·
i agree with Dan. I would even not replace thermostat if you do not have any specific problem. it is cheap and replacement is simple. I guess water pump, if original, must do 200.000 km for sure if not more. MB overhauls their pumps (no new OEM pumps on a market) and they are ca 300 eur here. they return 20 eur for an old one.

regarding a short hose on thermostat: i needed to buy a new one after trying several hours in the middle of the winter. later I realized that like ever hose it has two ends :) and it really matters how do you position it. So if it does not go smoothly in one way then you know you must turn it for 180 degrees and all will be fine in less than 40 seconds :).
 
#7 ·
One of the previous owners did the water pump in mine sometime between 180,000-210,000 km (according to the guy i bought it off that is). I replaced the thermostat and fan clutch at 220,000 km which were original and had long since failed. The radiator is original and also the hoses by the looks of things.
 
#9 ·
in addition to my opinion above: i think coolant hoses on this car are for ever. same said my mechanic (in times when other people maintained my car). Once i replaced upper and lower radiator hose but i was not able to see any defect on old ones (20 years). waste of money and time.
 
#10 ·
Well they do not last forever in Arizona :)
I may not be professional mechanic, but i will recognize the condition of the hose when I see it. All rubber exposed to engine heat is in pretty bad shape, so i'll change all of them anyway. Rubber is still pliable, but you can see its age.

Anything else w140 specific when you change hoses and do the flush? I'm planning to do it orthdox way, not pressure bleed.
 
#13 · (Edited)
Are you reading my mind??? :)

Any specific cooler which fits with stock AT hoses? The reason i ask for fitment - i just bought new set of two hoses for AT fluid. Also i was under assumption that they actually have some sort of bended tube instead of the. Feed to collant radiator, am I wrong?

I'm in OH, but. The car is from AZ, one owner, spent all 22 years there, not a single rust spot anywhere.
 
#12 · (Edited)
Alter, I'm confused (most of the time). :| Your profile says Ohio but you just mentioned Arizona. I'm in the Plam Springs area and have no need for excessive coolant since it is not a very good conductor of heat. So in my 21 liter cooling system I have 4 liters of MB coolant and 17 liters of distilled water. Works well for me. And when you change the "tee" be sure and change the hoses connected to it. My "tee" was indestructible (they must have gone to a harder plastic in the '97 models) but the original hoses were bloated and ready to let loose.
Anziani
 
#14 ·
Well they do not last forever in Arizona
I may not be professional mechanic, but i will recognize the condition of the hose when I see it. All rubber exposed to engine heat is in pretty bad shape, so i'll change all of them anyway. Rubber is still pliable, but you can see its age.
interesting. my hoses were like new when i put them in the garbage can. sometimes i wonder if particular parts (used materials) build into our cars are different for USA and European (japan) market. Just for instance (this topic is off); I noticed that control arm bushing are pretty frequently "on a plate" in this forum. i just came back from body shop for MB vehicles and i asked a guy who works in reception about my control arm bushings. he said he only has one case in his career that bushings were bad and the car had 550,000 km. My ex-mechanic said almost the same in another words: my car (with ca 350,000 km in that time) should not have any problem with control arm bushings according to his experiences. Just to think about it, even if my assumption is true it has little or no effect in practice.
 
#20 ·
My 94 S420 has a transmission cooler in the bottom of the radiator like every other MB I've ever owned.

The tube in front of the radiator is for power steering. They just run a single metal line in front of the radiator and loop it back to lower the temperature of the power steering.

Dan
 
#18 ·
ok let's wait for someone with 1994. i can inspect situation tomorrow if you wish. i remember two hoses (in/out) from AT into "coolant radiator" which evidently has some space for cooling AT fluid. However there is also one small radiator if i recall correctly, I have never studied it ... but I can do it. i am ashamed to admit it.
 
#22 ·
In nearly every Mercedes I have working on since the 60s, the transmission cooler has been in the lower (bottom) part of the cooling system radiator. There are two flexible lines, typically with wire guards to prevent damage in the event of a belt being thrown, going to it from the transmission.

In diesel models there can also be an oil cooler mounted on the side of the radiator as well, however, it is a separate part. Later diesels (W126 2nd Gen and later models) have a separate oil cooler that resembles an aftermarket ATF cooler mounted on the left front of the car behind the lower bumper.

Dan
 
#23 · (Edited)
Excellent! Thank you!
I'll check the condition of the radiator, two more questions though:
1. Is there any way to clean/purge this radiator part? I can imagine it is getting clogged fast and difficult to clean, if tubing is uniform throughout the radiator.
2. If there are any issues, do i have to get Rein or i can get away with Nissens one? Both are designed the same way.

I doubt if ti is rotted, but can be clogged with atf deposits.
 
#24 ·
In the nearly 30 years I have been working on MBs I have never seen a clogged transmission cooler. I have seen them leak, however, but that isn't common to my knowledge.

I believe the original radiator was a Behr. Nissen and others do make replacements, but I haven't used any of them, so I would have to defer on that to others.

You might want to consider taking it to a radiator shop have just having them clean and test it.

Dan
 
#28 · (Edited)
Guys, this is corelated question, but not exactly about pump.

If my radiator/transmission cooler is not clogged and functional... then i should see ATF coming out of the transmission hose on the driver's side, right?
In other words, if i disconnect hose on the driver's side from the metal tube going back to the AT, and start the engine, i should see fluid coming out?

I did not see any, when i tried it... so either radiator is clogged, or there is thermostat or somening else regulating the pressure going towards radiator.
If i'm not mistaken, passenger side hose is sending fluid to radiator, and drivers side is the return.

Please advise! Thank you in advance!
 
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