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Serpentine belt pulleys in unthreaded water pump holes?
Experts, I've bought an after market water pump for M272 engine, and the two top holes where the serpentine belt pulleys are to be installed are not threaded.
How are those pulleys installed? Are there some backing nuts and no thread in the holes, or am I supposed to thread the holes? Thanks!
Sounds like a possibility. Unfortunately I don't have the original bolts (it's a project build with new parts). Maybe I'll buy those bolts directly from Mercedes to ensure the right size/type/self threading, unless there are different suggestions.
Dzięki!
Last edited by George993; Sep 15, 2021 at 11:37 AM.
Bad news, the size of the holes in the pulleys is 8.2 mm and the size of the unthreaded holes in the water pump is 8.4mm, which is a size for threading M10x1.5
M10 bolt will not go through the pulley hole of 8.2mm
Is anyone having both the pump and the pulleys (and the bolts) and can comment on the sizes? One of the pulleys came with M7 bolt. Thanks!
Pump or the pulleys, that's why it would be great if someone with those parts on hand/doing the job could confirm the hole dimensions of both the pulleys and the mounting holes, thanks
More information, looks like Mercedes OEM is using BOTH threaded and not threaded water pumps depending on the engine number. Same with after market water pumps, can be both threaded and not threaded. Which means that the pulleys most likely also have two hole dimensions, unless the threaded water pumps are already threaded for M10x1.5
If it was that simple we would not have this discussion.
The engine came from a car with a completely different VIN, completely different water pump matching that VIN (and matching that engine number), and completely different accessories than the car I'm building.
Those pulley use a M6 or M8... definitely not M10 on W212 M272. OEM INA pulleys, the smaller composite one comes with a bolt and the larger metal one did not. As mentioned, your best bet is using the VIN off the car the engine came from or find the P/N stamped on the original parts... which I guess we may suspect is a W211.
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