[v8volvo]

A trick for making removal and reinstallation of the vacuum pump easier:

Before loosening the vacuum pump mounting nuts, first rotate the engine (either with wrench on front of crankshaft or by "bumping" the starter motor) until the small V-notch in the injection pump pulley is close to aligning with the TDC mark on the pump bracket. It does not have to be dead on, just near it. This will put the camshaft in a position where the cam lobe that drives the vacuum pump is close to minimum lift, taking the heavy spring pressure off the pump. This way you are not fighting that spring while you remove the pump and try to put it back on, makes it much easier and limits the risk of damage to the parts.

It is common to find that someone in the past has spread a large amount of RTV sealant on the pump to seal it to the head. That is not necessary and eventually leaks. The best way to get it to seal up is to NOT use any gasket sealer, ONLY use the rubber O-ring, which tends to last a very long time. Try to clean off any remnants from past use of sealer to remove all of it. New o-rings available from Volvo dealer or aftermarket.

A little bit of vaseline or grease can help hold the O-ring in the pump recess as you reinstall it, otherwise it sometimes wants to jump out of position and then get sliced when you try to tighten the pump down.