Hi all.

I'm working on my brother's 1975 240D as his timing jumped. Turns out the cam roller mechanism in the vacuum pump came apart and a piece of the mechanism either made to the chain / crank gear or caused the cam to jam momentarily, causing the chain to jump. I found a small piece of white metal under the valve cover. Apparently the chain jumped on the crank gear, as both the fuel distributor and cam gear were out of time.

Long story short, I've reset the cam and fuel distributor, and replaced the vacuum pump with an extra 123 vacuum pump that I had in my garage.

Still having trouble getting the car started, and thus this question.

The old style pump had an exhaust on the pump that went to the intake manifold. The new pump has an internal exhaust to the pump. There's a check valve going in, and I know the car was running without the pump functioning..

Is there any reason the new engine wouldn't run with the new pump? Do I need to plug the inlet to the intake, even though there's a check valve on the tube?

Would the internal exhaust do anything to prevent the engine running?

It's likely that the lines still have some air in them and this old man will start, but I'm concerned that the new style pump may introduce some problems either by the internal exhaust or the lack of exhaust to the intake manifold.

Any comments or speculations would be appreciated.