I have a leak from the bundle of hoses in the center of the photo, under the air cleaner by the turbo. I wish I knew the name of it. I have checked Pellicanparts and see nothing like it in their parts catalog.



Is this something repairable with an O ring or a replacement. There look to be multiple hose clamps, I can't tell exactly where the leak is coming from.

Ideas please

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1999 Mercedes E300TD daily driver sold at 238K miles 106K miles were mine, rust worm got it :-(
2006 Mercedes CDI new daily driver! 56,000 miles May 2016 now 85,625 Apr 2018 and Apr 2019 101,000 miles Apr 2020 109,875. March 2024 135,250, Dec 2024 145,000 miles

That is your auxiliary coolant pump

001-835-86-64

$305 from Pelican and no you can't order the internal o-ring separately.

I would first try to see if the hose clamps are all tight.

The air filter box is very easy to remove and then you have lots of room to work on the connections.

I would also check the junk yard for a replacement.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Unless you live in a terribly cold climate and don't get enough heat out of the heater, you can simply remove the pump, insert a pipe to replace it, and tape off the electrical connection.

x2 on living without the pump....mine doesn't work on the 98, I live in New England, and I don't miss it. Not a chance I'll ever replace it.

__________________
14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 159k miles
06 E320 CDI "Rutherford", Black on Tan, 179k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 145k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 77k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

Thanks to all.

I was able to get access and slightly tighten 3 of the 4 screws that hold the pieces together. I was also able to only slightly tighten up the 2 larger clamps.

If it still leaks I will take it apart and examine the parts.

If I bypass the pump, it is obvious that I connect the large hoses together. What do I do with the smaller hose and where does it go?

__________________
1999 Mercedes E300TD daily driver sold at 238K miles 106K miles were mine, rust worm got it :-(
2006 Mercedes CDI new daily driver! 56,000 miles May 2016 now 85,625 Apr 2018 and Apr 2019 101,000 miles Apr 2020 109,875. March 2024 135,250, Dec 2024 145,000 miles

The small hose is the heated washer fluid loop. Washer heater is in parallel with the cabin heater so you'll need to find the other end to cap off as well.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Thanks for all your help Jay_Bob.

I took the pump out today, disassembled it, cleaned it up and hit it with brake cleaner. It was not obvious where the leak is from.

I reassembled it with red high temperature silicone gasket maker. Hopefully I did not use too much and glue the pump rotor solid.

It is not leaking after a couple of runs bringing the temperature up to 80 degrees operating temperature. So far so good. If it leaks again I will likely go aftermarket from ebay MotorKing for $61.95

It is so easy to R&R it could easily be replaced or bypassed on the road.

__________________
1999 Mercedes E300TD daily driver sold at 238K miles 106K miles were mine, rust worm got it :-(
2006 Mercedes CDI new daily driver! 56,000 miles May 2016 now 85,625 Apr 2018 and Apr 2019 101,000 miles Apr 2020 109,875. March 2024 135,250, Dec 2024 145,000 miles