When the Delivery Valve Holders are removed from the M type Fuel Injections pumps you don't want to do anything that causes the Barrel of the Element to be pulled up as if it comes up fare enough and out of the alignment slot it can cause problems.

This has happened a few times to some who have changed the O-rings and the Crush washers on the M Type Fuel Injection pumps.

For the same reason do not rotate the Engine without The Delivery Valve holder being tightened down.

Before loosening the Delivery Valve Holder make sure there is no dirt down in the threads that is going to fall into the Fuel Injection Pump as you back out the Delivery Valve holder.

If your M Pump has the Port for it you could rent or buy a Timing Locking Pin and time it with that although that is not what it is specifically made for.

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84 300D, 82 Volvo 244Gl Diesel