Putting this 08 GL 320 back together after the oil cooler job. It had some oil in the coolant system from the leaking seals and the cooland reservoir has oil coating the inside. I pulled it off and rinsed it out with Dawn and hot water, let it soak for a while etc but this did not do much. Does anyone have a trick to cleaning these out? Seems impossible with all the chambers inside the tank. Or should I not even fool with it and just replace it? I am planning on doing a round or 2 of dishwasher detergent to get rid of any possible oil in the rest of the cooling system.

Try citric acid. Typically you can find in in grocery stores, Wal-Mart etc in the food canning section. Also sold as coffee maker cleaner but at 3x the price.

Excellent degreaser, it a powder so you can mix, strong/weak and soak the tank.

If the car is a clean keeper, replace the tank. Old tanks in addition to be contaminated are brittle and are a relatively high potential failure point.

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Citric acid does not clean oil out from what I recall. Typically first you degrease the system then do the citric acid flush to remove rust and scale. I am going to do the degreasing but I don't really have any rust or scale to remove.


I am leaning toward just replacing the tank, they are not that expensive anyway.

Replace it the silica pack only lasts 15 years .

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92 e300d2.5t
01 e320
05 cdi
85 chev c10

No modern coolant formulation requires a silica pack. I’d not be worried about that. Cracking and leaks on the other hand…


OP, I think I’ve seen some YouTube videos in the past on dealing with it. As I recall? It included some strong chemicals, a cleaning agent that scours the inner surfaces, and maybe a go in the dishwasher.

Here:

https://youtu.be/JqCN7VHMtfQ?si=BVJYt****MqwDLlq

https://youtu.be/bIOmP1-dLPs?si=D0Twqr2VM4wpsPmZ

__________________
Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (116k)
1991 350SD (206k)
1991 300D (228k)
2008 ML320 CDI (199k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (267k)

Past Diesels:
1983 300D (228K), 1985 300D (233K), 1993 300D 2.5T (338k), 1993 300SD (291k)

If you don't mind changing it every 3 years or so, then as long as your existing tank's still in good shape, then you can stick with that. If you'd rather be on the 15-year change interval, though, then a new tank with new chemical pack is in order.

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92 e300d2.5t
01 e320
05 cdi
85 chev c10

Sorry, there’s no such thing. Never was.

Even in heavy trucking where SCA additives are used and coolant analysis is done, it’s not that long.

BASF Glysantin G-05, and the variants licensed by MB and valvoline are marketed as a 5yr/150k coolant. Adding silicates (which drop out, and mind you, this is a HOAT coolant) don’t triple life.

Do what you like. I know my systems are pristine running G-05 at the correct intervals, with no concern about added silicates that drop out and impede heat transfer.

__________________
Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (116k)
1991 350SD (206k)
1991 300D (228k)
2008 ML320 CDI (199k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (267k)

Past Diesels:
1983 300D (228K), 1985 300D (233K), 1993 300D 2.5T (338k), 1993 300SD (291k)

Oh wow you are so funny JHZR2.....

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92 e300d2.5t
01 e320
05 cdi
85 chev c10

What’s funny? That I might know something about coolant chemistry and how this stuff works?!?

State your credentials that you have the right or knowledge to laugh at factual statements I’ve made.

Oh, and if someone decides to run a modern OAT coolant with a new silica pack, guess what happens then? Jelly sludge. Remember the issues with dex cool early on?
Who is laughing then??

__________________
Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (116k)
1991 350SD (206k)
1991 300D (228k)
2008 ML320 CDI (199k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (267k)

Past Diesels:
1983 300D (228K), 1985 300D (233K), 1993 300D 2.5T (338k), 1993 300SD (291k)

An interesting read about MB coolant and the additive

https://www.mbca.org/sites/default/files/antifreedec04_0.pdf

Not sure if this is the latest info or not, but according to this article 2003 was first year the silica pack extended service started. They do mention to expect future extensions of the list of applicable model/year mix.

Sodium metasilicate 5%, is the compound specified in the de-oiling step for cleaning and de-scaling the cooling system. The de-oiling step is specified, PRIOR to the separate de-scaling step with 10% citric acid.

It has been available from MB Dealers in the past. Red Devil TSP/90 Heavy Duty Cleaner is the same stuff. Search for it online. It's available in some stores which carry house paint. It's used for wiping down/cleaning and etching surfaces to be painted; as paint prep.

It dissolves easily in water. You could try removing coolant overflow tank from the car, and then filling the with the 5% solution, then moving the tank around to get the solution to move into all of the partitioned spaces, and allowing the tank to sit for hours to days. I have used rubber stoppers in each of the hose connection holes, and also put a radiator cap on the tank. Avoid skin contact with it- ie, wear gloves; it's hard on skin.

I've done this on both the original and replacement tanks with moderate success. With the newer tanks which seem to have more partitions, it has been more difficult for me to get the solution swished around into the different chambers.

Like others have suggested, getting a new/replacement tank is another, worthwhile option.

Edit to add: I am referring to the degreasing/de-scaling procedures for the older (eg, 1980s, W123, W124, and W126) diesels. I am uncertain if my experience/instructions pertains to your car. May I suggest that you check the factory service manual for your car/model year. Best wishes, and I am interested in follow-up.

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Marshall Welch
Seattle, WA
1982 300D-T

In the instructions for preparation for a citric acid flush, I believe the degreaser was dawn dish shop/detergent. However, you need to read some of the threads on that.

__________________
84 300D, 82 Volvo 244Gl Diesel

That article shows a few cars with the “15 year” claims on G-05. Note the actual manufacturers claim 5/150k.

Mercedes also had claims back at that time about oils and long drain intervals, and faced big issues.

Mercedes also now uses G-48, back specifies even to the old 617 diesels, if you take their word for it. It too is an HOAT with a small dose of silicate.

Trust a 15 year claim with a silicate pack at one’s own peril. G-05 and G-48 just aren’t designed for that.

__________________
Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (116k)
1991 350SD (206k)
1991 300D (228k)
2008 ML320 CDI (199k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (267k)

Past Diesels:
1983 300D (228K), 1985 300D (233K), 1993 300D 2.5T (338k), 1993 300SD (291k)

The article shows that MB did indeed have that metric established for select systems. 15yr/150k mi.

Not sure what the focus on the time recommendation are from either manufacturer, both are irrelevant. Usage is the primary layman's measure, and they both agree on 150k miles regardless of the time interval that's achieved in. Mileage itself is not a great measure, but easily understood by most.

The best approach is testing. Accustrip and others make testing strips that are coolant type specific, are inexpensive and give you a wealth of info on the true state of your coolant rather than some woefully inaccurate rules of thumb.