Vacuum Help
 

I have a 1981 380sl, on the vacuum diagram it says "air pump" what is this air pump reffering to, and where is it? Is it talking about the A/C compressor?

It is probably below the alternator. It is belt driven. Part of the pollution control system. It pumps oxygen into the exhaust to reduce O2 emmissions.

couldn't it be the electric Vacuum air pump in the boot (trunk) which operates the central locking system?

Jim

I don't think the 12v vacuum pump was used until 1986. Epc shows the reserve tank under the rf fender on the 380.

It would be located below the alternator, and belt driven. Do you have a grey market vehicle, If so, like mine, it's not there, either is the frequency vale, bypass valve to mention a few. At least that what I have found

What do you mean grey market vehicle?

A vehicle that was not produced to US Standards and then imported to the US. Some legally, IE brought up to all US standards. Bumpers, headlights, cats, side door reinforcement etc.. They were done to varying degrees by the importer. The following are 107 models that can be found in the US but are all grey market.
280SL, 300SL, 420SL and 500SL.
Some, like the 380SL were made for most markets so a 380SL can be a US version or a grey market.
I have an '81 280SL that has no US updates. I have an '84 500SL that had an AIR pump and cats. It was imported into Texas and modified there.

The euro versions are more desirable to some than the US because they generally have higher compression and HP. Some also have the manual trans.

Wow - I thought the air pump was for pumping the tires up!

I never thought of that. I could have sweated a valve into the pump line in case of a flat. Shucks, I already removed the pump.