When I used to rebuild Fuel Injection Pumps the only time a delivery Valve Spring was replaced was if it was broken or had some issue that looked off when you looked at it.

We did inspect the Delivery Valves themselves to see if they were worn. However, in this case you are better off leaving it along; I don't recommend pulling up on the Body of the Delivery Valve as it can pull up the Element Body.

He could use Viton O-rings and He might not have to change them again.

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84 300D, 82 Volvo 244Gl Diesel