My car is a 1994 E320 (W124 with M104) with ~165k miles. The wiring harness and OVP have been replaced. The previous owner replaced the radiator.

I live in Phoenix and it is ~105 deg today. My temp gauge reads at or slightly above the mark above the 80C mark (I am not sure what temp it is because it is not labeled). The AC is used every day and will cause the temp gauge to creep up over that unlabeled mark.
I went to add some water wetter 2 weeks ago and found some tiny metal shavings in the bottom of the expansion tank. I did not see water dripping from the front of the motor but the expansion tank was low. I added water and the water wetter.

I was out over the weekend and when I got home and turned off the car the small hose on the expansion tank that connects to the hose to the thermostat housing blew off the expansion tank and the water shot out all over the garage floor. I reconnected the hose and decided to replace the thermostat. When I had the thermostat out, I saw tiny metal shavings in the thermostat housing - not many but the same type as in the expansion tank.

I tried to search for this on the forum but came up with many pages related to radiators, coolant, e320, even one about metal shavings but nothing quite the same as this in the time spent reading.

Where are the shavings coming from? I am guessing that it is the water pump? Can anyone shed some light on this problem? Where else does the water circulate that would pickup metal shavings?

I am sharing a car with my wife until I can get this fixed.

Thank you for any help,
Jim

The previous owner added some radiator stop leak product..it has particles that appear as metal shavings......

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1993 300E, 2.8 M104 .....

I am not sure a coolant flush will remove the shavings as they are small and are heavier than the coolant/water mix. Is this a problem for the shavings to be in there?

What explains the pressure build up that blew the small hose off of the expansion tank?

can you post a picture of the shavings you are seeing?

if its not a stop leak product, then some metal is grinding somewhere and needs to be addressed. the only thing i could think of would be the pump ....

flush the system out with a garden hose, put in new coolant or water (on a temporary bases) and see if what comes out....

the small hose could have blown due to age...the rubber weakens with time, and with the pressure, the weakest link goes first.....

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1993 300E, 2.8 M104 .....

Only spectrographic analysis can tell you where the shavings came from. Short of that, you can use a magnet to narrow down what you have.

The debris may have been there from the assembly plant since day one.

I agree with above that the only place the shavings could have come from post-assembly is the water pump, or maybe some repair work was done on the system (e.g., helicoil).

The cap on the coolant reservoir should release pressure before hoses blow off. Have it checked or replaced.

The only place in the Cooling System that can make Metal Shavings = the water pump impeller..

Thank you all, I will have the water pump replaced. I did replace the expansion tank cap after the hose blew off (when I replaced the thermostat).

I will also have the coolant flush done at the same time - I wonder how many flushes to remove all the shavings? Is it necessary to have a perfectly clean cooling system - void of even tiny metal shavings? I wonder because I doubt all of the shavings can be removed with a flush(es) short of tearing apart the motor and replacing the radiator tank?

I wonder what caused the water pump impeller to grind into flakes? Maybe I did not have the correct coolant? I was using the Zerex G-05 and water and finally added a pint of water wetter. Maybe the mixture was to much water?

Jim

Jim, recommend buying a reconditioned water pump from a MB dealer. It should be better quality than an aftermarket water pump, and less expensive.

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Fred Hoelzle

I looked at ********** online and found a Graf water pump for $165. It is not listed as OEM. One shop I called said it could cost $350 - $400 for the pump alone and 6 hours labor. I would like to spend < $750 for the total job.

Call the dealership as recommended above and price out a re-manufactured unit. If the price is agreeable with your budget, then shop around for a reputable indy who will warranty your Mercedes-Benz part and install it for you.

I am just suggesting a course of action. I think $700 is a very reasonable budget.

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2006 BMW M5 "Heidi" @ 109,000 miles
2005 MBZ C55 AMG "Lorelai" @ 165,000 miles
1991 MBZ 300E "Benzachino II" @ 165,000 miles
1990 MBZ 500SL "Shoshanna" @ 118,000 miles

(On the hunt for a good used M103 engine as of 6/10/23, PM me if you have one to sell!)

Are there other parts I should replace during the water pump job? I was thinking maybe the serpentine drive belt and the 2 hoses on the water pump. How about the belt tensioner? Is this a common part to replace on these cars? I will already be paying for the labor so it is only the parts cost (again, to come in under $750 total).

I am not sure if the clutch fan is working or not - with the motor cold, I spun the fan and it went around approx. 1/4 of a rev.


Jim

Jim, you will find that owning/maintaining an older MB automobile is only practical if you are, or become, a DIY'er. Most jobs, such as replacing a water pump, are fairly straightforward if you have average mechanical ability, basic tools, and a repair manual (or search on this website for step-by-step instructions).

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Fred Hoelzle

I do car work myself when it makes sense and is cost effective. I got the idea from reading other posts here that replacing a water pump on this car is not a novice level job. If it takes a mechanic 6 hours then it would take me 3x longer which means I am without the car I use to get to work for at least 2 weeks (I can only work on th car on the weekends).

No matter who does the work, the question I asked in previous post is the same: when you replace the water pump on this car what other parts make sense to replace?

Jim

It does not take mechanics 6hours. And it sure won't take you 18hours.
The 'book' time is always at a comfortable pace. Most mechanics could probably do it in 2.5-3hours.

Took me about 4hours.

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2016 Monsoon Gray Audi Allroad - 21k
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