Question?? 1986 300SDL 190,000 miles and still on original water pump. Should water pump be replaced as precaution? Car is strong and runs and looks great.

87 SDL. It was actually pretty easy. I was at 210K and everything had been fine till about 209K, then I noticed small leaks in the driveway and eventually big leaks in the driveway - I didn't have to really drain the system to begin with.
a few suggestions for you if you should decide to change it out:

Even though the manual doesn't mention it, pull off the top radiator hose and refill directly into the block till you fill to the top, then refill into the expansion tank. This was the only way I found to get the right amount of coolant (or water to flush system) into the system. You'll still have to "burp" it when everything is done and you've driven awhile; i.e. add coolant to proper level.

Also, be aware that it can be a bit tricky to keep the gasket on the new pump as you put it on, especially at the bottom of the pump. Of course, I missed on mine the first time and had a huge leak when I put everything together again. The positive side of this... I can take the radiator out and the pump off and have a new gasket in in about 45 minutes now. I ended up useing a tiny bit of glue stick material (the kind you can steal from your kids/wife's school supplies) on the outside edges next to the bolts. I've read here on the forum that the actual gasket goes on dry.

oh, and check your vacuum pump while you're in there. There are pictures on this forum (do a search) that show you the better vacuum pump to have. Evidently the old style has a habit of exploding bearings into the timing chain area and seriously damaging your benz. I forget what the new ones look like, I checked mine found it ok and then forgot about it, but a search should pull up the info directly.

anyway, that's my $0.02, good luck should you decide to change it out.

cheers,
Matt.

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-livin' in the terminally flippant zone

I would worry more about the vac pump if it is the old style. But the water pump runs about $85 from the dealer and is simple to change.

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