When the vacuum pump falls apart often pieces fall into the timing chain and gears throwing off the valve timing and pistons hit valves.

Sometimes when that happens it cracks the aluminum camshaft bearing towers and can bend valves and so on. Remove the valve cover and inspect the bearing towers and also look at the valves and so on.

Also, before you put the vacuum pump on what did the supposed to be smooth face of the timer that operates the valve pump look like?

Behind the timer is a thrust bearing. When there is too much end play that can ruin the vacuum pump. If you put a new vacuum pump on that can also get ruined because of too much end play.

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84 300D, 82 Volvo 244Gl Diesel