AO Silver Member
Join Date: Apr 2002
I think it's just a case of letting the cooling system work it out for itself, monitoring the level is a good idea though.
The sucking sound is quite common with modern manifold in either cast alloy with rather thin walls, or plastic manifolds. I can't remember whether the 146 Ti were fitted with the variable intake manifold(plastic) or not. If you suspect a leak, buy yourself a can of diesel/easy start, and in a well ventilated area, let the car idle and spray the manifold and hoses running to and from the manifold with easy start. If the engine then pickup revs you have found a leak. Remember to do this in small increments, as large amounts of easy-start in the enginebay can catch fire and cause an explosion. A rather stupid way to waste a car. eek!
Lean mixture does cause higher engine temperature, but this is mostly when cruising at higher speeds, so this shouldnt cause any probs while idling.
All the best