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Discussion Starter · #1 ·
Well i'm still working on my fiancee's Dad's 450SL and decided to look into his #1 problem today.

Basically the driver's side drain tube from the blower motor housing/basin plugged up at some point in the past causing the water to back up and rust out the blow motor basin. The whole driver's side drain tube mounting flange is gone so there is nothing to even attach the drain tube to.

The passenger's side tube is ok and the flange is intact, but there is some slight rust on that side as well.

Any ideas for fixing this? I'm thinking it might not be so bad to fix if i have the hood off and blower motor out. Maybe i can make a mold of the basin with aluminum foil and make a new basin out of fiberglass that can sit inside the old rusty one? I could put flanges on the new basin for the tubes to attach to.

Pretty big hassle, eh?
 

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1977 Mercedes 280SL, 2002 Mercedes CLK 320 Sport, 2009 Mercedes ML350
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The 107sl buyer's guide has a whole section on this. Basically, you make two cuts into the metal underneath the vent covers, in order to peel it up. This will give you access to the basin area, then wire brush it out, treat the rust with phosphoric acid, then paint it with something like Rust Bullet. If it's rusted through, then fiberglass it up. Then bend back the metal and weld it up (or whatever). On the driver's side, I would then cover the vent opening, to prevent further water going in.
 

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Discussion Starter · #3 ·
Hrmm. I got to the area by removing the black plastic cover in the center of the engine bay/firewall.

By vent covers do you mean the "grills" on either side of the car where the air comes in? Those look to be only riveted in place.
 

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1977 Mercedes 280SL, 2002 Mercedes CLK 320 Sport, 2009 Mercedes ML350
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First remove the grills - which are held in place by plastic - reusable rivets. Punch out the pins in the middle of the rivet to release them. Then you can cut out the metal under the grills. How extensive is the rust? If it's just around the blower motor, than you don't need to do this - you can just treat the rust around it. If the rust extends to the side, than you do need to cut access to it.
 

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Discussion Starter · #5 ·
locally the rust is only in the center part. i have it all apart and cleaned up and soaking in deruster now. i'mgoingi to fiberglass it, shouldnt be too big a deal.

however, intaslling the new drain hose might be a huge pain in the butt. any tips for running the hose along the tranny tunnel without taking out the whole center console?
 

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Discussion Starter · #6 ·
nevermind i see now. the hole seen from below is already above the tranny inside. no biggie at all.

I'm fiberglassing in a 5/8" brass barbed fitting and using 5/8" ID heater hose. outta work well i think.
 

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pictures...Please....

just in case someone else has this problem...
 

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1985 500SL 130K (Horst)
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