What can i use for the water pump to block gasket? The MB stuff, or Permatex Ultra Black, which is very similar to Loctite 5900?

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1984 380SL-driving and service privileges.

mb recommends it go on dry
can use small amount of permatex to hold gasket

cool, i can just use a spritz of 3M 77. Now for the water pump, Graf or Laso? What are the torque values?

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1984 380SL-driving and service privileges.

I just used the blue Hylomar on my water pump gasket (and vacuum pump gasket). Worked great. I am now a convert and will not use anything else on gaskets.

I went with Laso since my Graf pump went bad in approx. 35000 miles. And the Graf was a replacement for the original pump. I had a local shop do it and they let me chose the brand that I wanted. One year later, no problems.

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Paul 1987 300 SDL; 2000 ML; '69 MGB; '68 VW Fastback

Laso is the OEM brand, costs more and last much longer.

I always use red "aircraft" Permatex on paper gaskets. Don't know what the gasket MB uses looks like, the one for my brother's 300D looks like rubber impregnated paper and may not need sealant.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

On a smooth surface, the old "INDIAN" gasket shellac serves well to hold and seal gaskeets. Ued on my 63 Corvette waterpump paper gaskets, works fine (always did). Sometimes the simpler things work best. (Silicone base cements can tend to peel). Abe G

Silicone sealant + water pump gasket = certain leak. Silicone RTV sealants won't work anywhere near glycol or water.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

I just replaced the water pump in my '86 300E with 120k mi. The original seal is simply an O-ring, and it appears to have been installed with no sealant of any kind. The old O-ring was squashed completely flat, but there did not appear to be any leakage at all. I used 4 tiny dabs of grease to hold the new O-ring in place during installation, but no sealant. Here's a picture of the old pump and O-ring:

Attached Thumbnails

 

Interesting that: 1.Last summer, when I had my local shop replace the water pump, the Laso pump was $23.00 LESS than the Graf (This site). Now, as you said, the Laso is more expensive! 2.The local MB Dealer was the place that put the Graf pump on, several years ago. 3.Speaking of prices, the price of a AC suction hose more than doubled in about a year's time for my '87. (This is after checking more than one parts site.) - I write down prices of parts that I might need in the future and file them.

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Paul 1987 300 SDL; 2000 ML; '69 MGB; '68 VW Fastback

I recently replaced the water pump on my 300e and used no sealant. It is the o-ring type of gasket.

I did my water pump by the book -- replaced the o-ring and used no sealant. I did meticulously prep the mating surfaces, finishing with Scothbrite, and put a thin coating of silicone grease on the new o-ring for better seating.

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95 E320 Cabriolet, 159K