'95 E320 wagon > overheating / water pump

Car overheated with the loud "pop" of a broken hose as it was being parked. Now in a garage (90 mi from where I live) that is telling me that a
new "Mercedes" water pump will cost me $400 and the (book) time for the job is 8 hrs. (@ $90/hr). So, $1200 to replace a water pump... Am I getting taken to the cleaners? Does it matter that it is a Mercedes pump? (I see lots of others for ~ $275). Are there other things that might be the problem? Thanks for your help. -Bill
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A hose broke (pop) and the motor overheated (so fast?) while parking?
Or did the hose break because the motor was already overheated?
You're uneasy about the claim that a water pump is needed. It shouldn't be -- unless its seal is leaking and is the cause of the overheating.
The cut and run decision is to replace the blown hose, fill the coolant and drive it home. That's IF the water pump isn't leaking.
This straight six is long and fills the space so working on the water pump isn't a picnic. Check www.autohausaz.com for the part(s) if you're considering a DIY project.
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I totally agree with Tom.
Can't think why parked car blew its hose. Which hose is this? Radiator, heater or other coolant hose? Where is it? What is the cause of overheating? Leaking pump or hose?
IIRC, this engine is M104, same layout as our 96 C280, just slightly more displacement. Replacing the water pump on this engine is time consuming (though straight forward). It took me 6 hours. Some components block the way, like power steering pump (relocation, not removal). No special tool is needed.
Autohausaz quotes the pump as $172 (list price is twice). The garage probably also includes the part/labor to replace the hose. Depending on which it is, some hoses (for example, near the firewall) may require up to 3 hours labor.
When I replaced the water pump on our C280, I also replaced all hoses around that area. It is almost the same labor. Later a hose near the firewall broke. I then replace ALL remaining coolant hoses (another 6-hour job).
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I suggest you tow it to your mechanic or consult with your mechanic. Do you have AAA Deluxe? Deluxe will allow you to tow 100 miles with no fee.
AutohausAZ.com is where I buy all my parts.
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New info: The car had been overheating for 20 min. The "pop" turned out to be the plastic reservoir on top of the core blowing out a section (this was at 10:30pm and I didn't have a flashlight). A new radiator & thermostat and fluid replacement will set me back $700. The pump is not confirmed to be damaged...or working. I just don't understand what blocked up the system, how this could have happend unless the pump failed.
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A water pump can only pump coolant, not vapor. I suspect the coolant leaked out and the motor overheated. That the radiator bust is a consequence, not the underlying cause. A new radiator is needed. A new radiator costs $175 to $198 at www.autohausaz.com; the plastic expansion tank (where the coolant is filled) is $35. Given the prices you are hearing it may be worth trucking / trailering the car to another shop.
These straight sixes are known to blow head gaskets after about 150K miles due to the differing coefficients of expansion of their iron block vs. alloy cylinder head; yours may now be one of those.
There are two painful possibilities: A. head gasket replacement or; B. head gasket and piston ring replacement.
If the engine continues to overheat, especially if suddenly and quickly, then the head gasket is broken and must be replaced - no negotiation. Plus, if the motor burns oil then the rings have lost their spring temper (from being overheated) and need to be replaced. Note that one doesn't want to do the head gasket and then open the motor again to replace the rings.
These are ugly possibilities, hopefully that's all they are.
The only way to diagnose it further is to get it onto the road and see how it performs.
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Overheating 20 minutes is very bad. A couple of things to consider.
1. Need to check if head gasket is still good. A pressure test to the cooling system or a leakdown pressure test on the engine block can tell you if your headgasket is bad... air bubbling out of cooling system tells you leak or pressure leaking in cooling system keep dropping.
2. Overheating 20 minutes... if this is highway driving... it is most likely the thermostat... If overheating in local roads, most likely the fan clutch is bad and your aux fan trigger sensor is also non-functioning.
3. Pump rarely failed on its own unless the bearing on the pump is bad... which is easily checked by wobbling the waterpump pulley.
When you mean overheating, what temperature are you talking about? How long did it stay at that temperature before you shut down the engine?
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