The water pump on a 1989 420 SEL is growling, more predominately at startup. I'm thinking the bearings are a little worn and the pump needs to be replaced.

I got a rebuilt pump from the dealer, 116 200 17 01 88 but when I opened the box, the pump is a little different than the one on the car. My EPC says that is the right part number for the car. The new pump has a brass tube, coming out of the bottom of the shaft, angled down at 45 degrees towards the front, and the tube is about 1" long and a 1/4" in diameter. The pump on the car doesn't have the brass tube. The new pump casting has the number 117 201 10 01.

Its this the right pump? Should something be on or over the brass tube? If I leave as is, will coolant pour out the brass tube? Was the wrong part put into box?

When replacing the pump, the service CD indicates the distributor needs to be removed, but does not mention the harmonic dampener. Some posts here indicate the harmonic dampener needs to removed. Where is the harmonic dampener and does it need to come off? The big crankshaft fly wheel does have a notch.

Finally, do the gaskets go on dry, or should they be dressed with something?

Thanks for helping.

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1989 420 SEL

I cannot comment about the design variation between the old and newer pump.

Regarding the gasket - dry or dressed with sealer.

I looked at your pumps gasket at an online parts seller. This type of design is pretty much std. for front mounted water pumps. I've done a number of these types.

First off, ensure the engine surface is as smooth as a baby's butt. Be careful not to gouge the metal engine surface when cleaning. If room permits, 3M makes some abrasive pads that do a good job of removing old gasket material. These 3M pads were designed to be used with a drill or other rotary power equipment. If there's no room or you lack the equipment, you'll have to resort to elbow grease and medium grade sand paper. I spray on lubricant and sand to help remove the gasket material. Any kind of lube like WD40 or whatever, just something to help soften the old material. The spray on gasket remover products are in my opinion a big disappointment and they are dangerous if the stuff gets in your eyes.

You might be able to use a gasket scraper to get a long stretch of material off, but BE CAREFUL not to gouge the engine surface.

Ok - you've got the engine surface clean and your ready to put on the new pump.

To use gasket sealer or not to use gasket sealer. Which is it? Lots of arguments on this subject.

I would do one of two things.

a. Use no sealant
b. Use a product made by Permatex called "High Tack" in an aersol spray on can.

I would not use any of the goopy stuff that comes in a tube. This stuff can be used in cases where you're using it exclusively to build-a-gasket from this goopy gasket sealer. Sometimes people use this on differential covers where no gasket was ever installed from the get-go at the factory. It's been my experience that using this stuff on water pump gaskets is more likely to cause a leak than prevent one. You'll simply never get it on EVENLY.

The High Tack product is a liquid-like spray on, so you will not have unevenness like you will with gasket sealer. It can help seal surfaces with slight imperfections.

I hang the gasket off of something like a bungee cord, then spray both sides. Let it tack up for 15-20 mins. Lay the pump on a flat surface so that the gasket surface is facing up. I run long bolts up underneath and thru all of the mounting holes on the pump. The idea is to provide "guides" for you to use in order to get the new gasket mounted perfectly over each hole. Once you have each gasket hole over the associated "guide" bolt, you can gently lower the gasket down and on to the pump and everything will line up.

The reason for all of this precaution when mounting the new gasket is the VERY STICKY nature of the High Tack sealant. If you just throw the gasket on the pump, you may have a hard time adjusting its position once on. This stuff STICKS.

High Tack has never failed me.

My 2 cents.

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'91 300-SEL

If that brass tube on the front of the water pump you mention is coming out of the bearing drain hole don't worry about it. I recall hearing something about them adding a tube for drainage after a bearing failure to keep from making the engine compartment messy by the coolant getting on the belt and flying all over. Also that gasket info is great, I use the same guidlines, I did find however that the gasket provided with my water pump was made of rubber, it was just a rubber o-ring so I didn't use any sealer. When it is rubber I don't use anything just make sure surfaces are clean and even like mentioned before. I am not sure about the water pump on your car though. Good luck!
Brian

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Brian W. Heitman

www.MBCA.org/northtexas

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If your gasket is made of rubber you would not need sealer.

Photos of 420SEL gasket appear to be paper-like material.

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1HB00BPJD1HD0Q1YQJ&year=1989&make=MB&model=420-SEL-001&category=G&part=Water+Pump+Gasket

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'91 300-SEL

I have had excellent results using the old Indian Head shellac to hold gaskets in place (and some sealing). This is a old remedy (over 80 years). , and always works. Gives you plenty of time to shift gasket, and still sticks! just my opinion. Abe G

Thanks for all of the advice. The gaskets that came with the pump are like paper, not rubber.

Is the Indian Head shellac a brand name or will any shellac do?

I'll also try to find that permatex high tack dress. After getting gasket correctly on the pump, can I let dry before mounting to cylinder head? or do have to mount it while it still tacky?

I'll assume the brass tube is the drain tube. May be I'll even add a rubber drain tube onto the end, and guide its contents to the ground.

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1989 420 SEL

I have purchased the Permatex High Tack at NAPA auto parts stores. It may actually comes as a NAPA product, but will say High Tack on the can.

Once the gasket has been mounted to the pump, I'd wait a few mins, then mount the pump.

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'91 300-SEL

An old trick is to use a coating of white lithium grease on both sides of the paper gasket. It provides enough stickiness to make reassembly easy and when it is on it will very slightly swell to seal any minor surface flaws. When it comes time to remove for the next pump change, it will be a breeze! I've never experienced a failure to seal.

Tim

Thanks for the lithium grease tip, I have some on hand so I don't have to buy the permatex.

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1989 420 SEL