How do I know if I have an engine oil cooler and which water pump to purchase? If I buy the pump that assumes an oil cooler, is there anyway to just plug that outlet?

Contact your local MB dealer for a reconditioned water pump. They will supply the proper water pump based on your VIN.

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Fred Hoelzle

The M=B parts system has a bug so the dealer may give you the wrong pump. It happened to me recently with my son's C43. The C280 V-6 is not typically equipped with the oil cooler. The C43 with the V-8 is. The oil cooler is attached to the side of the oil filter housing. There are a pair of aluminum pipes that connect to the cooling system. there is a spud on the driver's side end of the water pump that connects to one of the pipes.

Like I said. it is unlikely you have the oil cooler.

Just a couple of things.

The M112 (your V6) and M113 share the same water pump, and generally speaking the only difference across various displacements and vehicles is the oil cooler outlet. But that's really easy to see, just look at the pump. On the right side of it, the end of it closest to the tensioner, you'll see either an outlet with a hose on it (smaller diameter, I think 3/4") or just a nub where the hose nipple would be. As vince notes it's unlikely you have the cooler, but it's about two minutes to check.

You can buy the pump through the MB dealer system if you like to spend money, but Graf and Saleri are OES and are sold by this site (through Pelican Parts) and are an excellent price. The Graf I bought was identical to the one I removed from my 2001 M112 engine, I think it cost $77.

If you are changing the pump and haven't already, I'd also recommend replacing the idler pulley, tensioner assembly and serpentine belt. All are wear items and can fail leaving you stranded; the original design of the tensioner on your car can also fail catastropically and cause collateral damage.

Good luck.

Yes, check idler pulley. If it has cracks in the plastic, put in a new one. I believe the steel spring type tensioner in this car is much simpler and much more dependable than the old rubber bushing arm type (typical in the w124s). It will probably last the life of the car, well at least 250m, which is all I hope for.

While the tensioner system is much simpler and easier to deal with than the old rubber bushing system, the pulley bearing is the failure point. To my knowledge the pulley is not available separately so the entire tensioner must be replaced if the bearing fails. On my 2000 C280 the bearing failed (without ANY warning - no noise, etc. - nothing) at 160,000 miles. Fortunately it isn't hard to change out on the road. On my son's 1999 C43 the bearing started making ominous noises at 100,000 miles.

My advice is to slack off the tensioner and spin the bearing occasionally to see how the bearing feels.

That's a good point. Not too many bearings will get to 150m and beyond.

Small problem I had with my WP was the 2 holes where the MAP bracket was attached. They were not tapped for the bolts so I just zip tied it in.

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