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1995 E320 Wagon, 2002 S430
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595 Posts
Discussion Starter #1 (Edited)
corrosion around this coolant level sensor

Anyone else with an M103 have issues with the coolant level sensor having antifreeze leak out around it causing extensive corrosion? Is there a type of solvent the will foam action clean away most of this corrosion/buildup? Will have to apply some JB Weld after cleaning it up to prevent further leaking.

 

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Mercedes 300 TE 24v SportLine -91 W124
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158 Posts
You should replace it.
Everything else is out of the question if You care about Your car.

If You release the holding ring around it and pull it out, You will see that there is a O-ring seal.
 

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'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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10,396 Posts
Wow.....I can't believe you're considering JB Weld for the fix.:eek: The O-rings are less than a dollar. Use a turkey baster or siphon to remove the fluid in the reservoir, remove the retaining ring, pull out the sensor and replace the O-ring.

Kevin
 

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'87 300TD/'90 300D/'94 Quattro/'89 Vanagon TDI/'01 EV Weekender VR6
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52,233 Posts
You should be prepared to replace the reservoir, sending unit & o-ring, as well as both the solder-on electrical connectors for the sender.
 

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About a dozen 1988, 1989, 1990, and 1991 sedans, wagons, 4Matics and 1 coupe
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5,466 Posts
Yeah, I'm with Zeitgeist. Replace the surge tank, coolant level sensor, and the o-ring and be done with it. The surge tank looks pretty yellow and probably has stress cracks. Plus there's a good chance that the sensor mounting bore is no longer smooth or round and that will cause sealing issues even with a new o-ring.
 

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Premium Member
'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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10,396 Posts
I actually cleaned my reservoir tank after the head job-I think it was the second anyway, but just slimy with oil. If I remember correctly, I used gas as the solvent and shook the hell out of it for a longtime. It looks like a new tank now...but agreed, if this is the original tank, replace with new. Probably the electrical connection can be cleaned up and examined for integrity.

Kevin
 

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Cruise Control
'87 300TD/'90 300D/'94 Quattro/'89 Vanagon TDI/'01 EV Weekender VR6
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52,233 Posts
These plastic coolant tanks are a wear item, like brakes, belts and hoses. Once they turn yellowish like that, they're no longer trustworthy
 

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Premium Member
'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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10,396 Posts
Not arguing that dude, read my post. If it's an original unit, replace. Mine was probably the second and came out almost white after I cleaned it. Replacing it would have been wasted dollars that could have been spent on a sensor or something comparable in price. Looking at his overflow tube, all is probably original.....

Kevin
 
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