Dear vp965,

Hope you're well. Most gaskets on 940s do not require sealants. As to the Pulsair system, if the clamps - that secure the stainless steel tubes to the head - are in good condition, no sealant should be needed. The Pulsair system parts diagram in Volvo VADIS - a superseded Volvo dealer parts/service database - shows only a gasket, but no sealant. Whoever applied a sealant likely was "over-zealous".

The clamps, shown in the photo, should be replaced, if - when tightened - they do not hold the tubes firmly against the head. These clamps - Part #1266663 - cost about $2.50 each at a U.S.-based Volvo dealer.

My guess is that with new gaskets, the Pulsair system will not leak.

As to the coolant sensors - which screw into the cast-iron block - it is not likely that the block's threads have been damaged. The sensors are brass and so of softer metal: over-tightening them will strip the sensor's thread, before the cast iron is damaged. Teflon tape should not be needed: the coolant sensors (for engine control and the temperature gauge) should come with thin copper washers, which suffice, if the sensor is tightened to "snug". I'd guess the teflon tape was used by someone, who lacked the copper washers.

Hope this helps.

Yours faithfully,

Spook