potatoman

Just bought a 1978 240d w/ A/C an manual transmission. Then the waterpump belt broke.

Got a belt for the waterpump and alternator. Got one from both Aurozone and Oreileys. Both were the same size, and both were too short. And online, there are varying sizes listed, with little explanation of their respective applications.

How do I know what to get?

kajtek1

Did you try EPC starting with your VIN? Your car is so old, that catalogs might not cover it, but in the past each automotive place had special tool to measure belt length.
You take the old belt, even broken one, they put it on the scale and give you matching size.

potatoman

Unfortunately the belt completely disappeared on the highway. I got a slightly longer belt (I think 950 mm), which got me home, However, it has clearly streched and would require adjustment of the alternator to most of the way out (is that amount of stretch normal?) I have little faith in Autozone and their janky crap.

What's EPC? i am not new to diesels, but this is my first old merc.

BTW, does someone make a serpentine belt conversion kit for these cars, kinda like the old ford V8s?

Edit: I didn't realize there was a section devoted to these cars. I'll try there. Thanks.

kajtek1

Electronic Parts Catalog.
Lot of parts dealers use EPC for a search, but I found that they start in year 1984.
Russians might have EPC that covers your year, but you need to add more data https://www.ilcats.ru/mercedes/?func...=1&language=en
Good luck with your car.

potatoman

Google has come through! It seems Pelican Parts has it figured out; they list engine numbers and sizes.
https://www.pelicanparts.com/cgi-bin...erTech%23item2

Any idea where I might find the engine serial number?

kajtek1

Did you try to pull datacard on Russian site I linked above?

potatoman

Yes, its rather confusing. I find six different part numbers for the water pump / alternator belt with no information on which is which. Clicking on each part number takes me to a sales website, again with no fitment information.

I also don't know where to find the engine serial number on my engine block. Where does Mercedes hide it?

kajtek1

When I enter VIN on Russian site, the first page gave me vehicle info with engine number on it. Than you can click "options" to get more data.
If anyone will have data for old cars, Russians will.
In US nobody check engine serial number as there is no use for it, but remember from Europe to look for it on the flat spot on engine block side. With dirt the numbers can be hard to read, but I take phone camera at different angles, flash/no flush and usually can read them on computer much better than directly.