Have you tried tightening first?

I notice my valves need a little tweak every few years. I pick up a slow leak with my halide detector and I can stop it by tightening the cores a tiny bit. The ones I have use rubber seals and I guess they just creep over several years

ETA also I’ve noticed there is varying quality in cores. The ones I’ve received with fitting kits on eBay have tended to develop leaks faster than those I buy from the shelf at Autozone…I think the brand is something like AC Pro. Their cheap but they aren’t bottom of the bucket like the ones that come in free with the schrader tool I order direct from China.

__________________
79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles
97 C280 147k miles

I think will order a valve core removal/install tool from ebay and give it a try to just tighten the leaking core. You might be right.

But it is quite disconcerting that it seems to be impossible to find out the size of those valve cores, or even any reference at all, and even less any MB part number.

I wonder how are the AC shops dealing with this when doing work that requires valve core replacement on older late 90s MB cars. One size fits all?

__________________
W163 ML230 EURO SPEC 1999
W124 300E 1986