One will never know what it did to the inside your body that breathed the fumes from the uninstalled vent. Stupid idea to put a lead acid battery in the passenger compartment. I bet with a good lawyer, you will win a lawsuit.

I believe AGM battery out gas less than a conventional lead acid battery, but it still out gas some, since it is still a chemical lead acid battery and needs to be vented if installed inside the passenger compartment.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Read up on the AGM battery and how it is built. I'm pretty sure there is no vent on them.

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Jim

Battery group numbers are assigned by BCI, which is a North American standards group. There is a European counterpart, Eurobat. Not sure whether the H codes derive from some rivalry there. The H sizes are slightly different from the ones they've replaced.

quick search top of list found this
Sealed Batteries Still Need Venting

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Bosch AGM with vent tube attached. Bosch Platinum Series AGM Battery Group Size H8/L5/49
Online at Pep-Boys with a $50 dollar code that is available at check out plus a $20 mail in rebate = $150 with free shipping.

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Just replaced my W210 battery with a genuine MB - it was less than $200 over the counter. It definitely has a vent tube. There are vent ports at both ends, so the shipping protective plate for the + terminal has a breakaway plug that you are supposed to insert into the unused vent port.

I too get about 13.3-13.5 V on the climate display under normal driving conditions. Really need to hook my Fluke 87 up directly to the battery and see what it reads.

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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

Agm still will vent at a rate of around 1% of flooded. There are still ventilation requirements per IEEE, nfpa and other bodies. The valve allows for better recombination, so notionally they will never dry out. Abuse (eg an alternator with too high an output) will let them vent and ultimately thermally run away. Beyond a certain charge rate they can also produce too much gas and vent.

That said I'm surprised that auto agm gives a vent tube attachment. The ones I've run have not...

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Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (116k)
1991 350SD (206k)
1991 300D (228k)
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)

Have you compared specs to the AGM Platinum group 49 from AAP? I think the AAP one has higher CA and CCA plus it's heavier. Heavier is better IMO (more lead).

The old battery I pulled out of there was a Bosch AGM so even these batteries can cause rust if the vent tube is not attached. The replacement NAPA lead acid was $110.

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CENSORED due to not family friendly words

Learn something every day - thanks.

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Jim

I seem to recall that my CDI sedan has the vent tube, and a vent tube orifice on the new Sears AGM battery I installed last Spring. Buy 'em online before you go to the store to pick 'em up if you're going with the Sears AGM.

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'06 E320 CDI
'17 Corvette Stingray Vert

Tjts: Nice job clearing that up before that rot took over.

Mine was missing the vent tube when I bought the car, but luckily there was no rust evident. (yet?) Are people still using stuff like POR15? Or are there better products nowadays?

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Current rolling stock:
2001 E55 183,000+ Newest member of the fleet.
2002 E320 83,000 - The "cream-puff"!
1992 500E 217,000+
1995 E300D 412,000+
1998 E300D 155,000+
2001 E320 227,000+
2001 E320 Wagon, 177,000+

Prior MBZ’s:
1952 220 Cab A
1966 300SE
1971 280SE
1973 350SLC (euro)
1980 450SLC
1980 450SLC (#2)
1978 450SLC 5.0
1984 300D ~243,000 & fondly remembered
1993 500E - sorely missed.
1975 VW Scirocco w/ slightly de-tuned Super-Vee engine - Sold after 30+ years.

For battery acid is advistable to wash the area with baking soda and water. That should neutralize the acid before you paint over it. I just used a few coats of primer because thats what I had in the garage and it dries relatively quickly. Por15 would probably work well too.

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CENSORED due to not family friendly words

There's some serious rust issues that develop when they leak!







.

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'06 E320 CDI
'17 Corvette Stingray Vert

The battery has arrived.
You had me worried about the weight of the Bosch battery compared to the Master Craft. I have weighed the battery and it is 59.5 pounds. The shipping info with FedEx said that it was 28.5 pounds; if it was that light I was prepared to not accept the package and move on to another option.
The specs are very much the same. The Bosch has 1020 amps and 850 cold cranking amps and the Master Craft has 1000 and 900 if I remember correctly.
The Bosch has a 4 year warranty with 3 years of emergency road side assistance and all of the other batteries that I investigated had 3 year warranties.
Thanks for you time. happy starting

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