With access to under the timing chain cover and the gear for the vacuum pump, can you determine if the pump could be making an awful knocking noise. Or if you pull it, can you check it on the bench. I am already to the point of being ready to pull head bolts, but if I can determine that the pump is the colprit, then I don;t want to pull the head, yet hate to put it all back together to find out that the pump didn't fix it!

Any help would be greatly appreciated, planning to work on it more today.

Thanks

If you hear the noise when turning over by starter just remove pump. If noise gone with pump removed you have it. Not really too hard to pull. Costs you a new gasket if not the problem.

If the pump is the source of noise you will be able to tell by looking at and feeling of the roller once the pump is removed. I would not recommend starting the motor with the pump removed since the crankcase will be exposed to the elements. You risk getting dirt in the crankcase and slinging oil all over the engine compartment.

Have a great day,

Thanks to barry123400 & LarryBible.

There is no chance of the motor starting at this point, the head is ready to be removed for the excpetion of needing to remove the ps pump.

Can I just use the starter to rotate the engine - what about the timing chain, will the tension make up the difference?

Thanks again - I will remove it and see what I find.

Is your question about the timing chain in relation to removal of the vacuum pump? If so, the vacuum pump is not driven directly by the chain. There is a disk in the engine under the pump that is rotated by the timing chain. The disk contacts the vacuum pump push rod and creates the pumping motion. Bottom line is the timing chain is still engaged with the vacuum pump disk even after the pump is removed.

Good luck!

__________________
1976 240D
1987 560SL
2007 E320 Bluetec
1998 C280 (now son’s car)
1982 240D Manual - Sold

Gotcha - Thanks

Simple to remove unless someone put a stripped allen on the bottom .

Now it is out, question, the roller seems fine, but when I compress it by hand it makes a popping sound and the old box spring noise I could hear when turning engine by hand is gone when it is out.

Is it normal for the pump to make that noise when compressing???

I would just replace it and move on, for the excpetion that I would have to put everything back together (as I have the head ready to be removed) to see if it works - yikes - Don't have that much free time...if I can help it.

As always thank you for any help that I can get.

The popping noise is not normal. I would disasssemble and try to determine the exact source of the noise. See DIY pages at the top of this forum...the vacuum pump rebuild section is great. A rebuild kit costs about $70 and is available from Fast Lane. If the roller seems okay and the pivot bearing seems okay, it is possible that the rebuild kit will take care of it. A new pump is $300!

Good luck!

__________________
1976 240D
1987 560SL
2007 E320 Bluetec
1998 C280 (now son’s car)
1982 240D Manual - Sold

A lot of junk engines in your area? If so you might want to go liberate a used vaccum pump from one. Make it really cheap though. Perhaps a usable pump as well? Or turn over the junk engine or even a friends 300d to compare noises if any doubt in your mind at all.