I changed all the smaller coolant hoses on my recently acquired '94 945T. The oil cooler hoses were on the verge of failure and one of the heater hoses looked original (so I replaced them both).

Ever since then I have been fighting coolant leaks, some fast others slow. The most recent one was at the firewall connection, sanded down any gouges that I may have put there when I cut the old hose off, and adjusted/tightened the clamp on the lower heater...checked my coolant level every day and it stayed constant. No more leak (there). The coolant level when the engine was cold was at the seam in the tank (say mid-way between Max/Min) and when it was hot the level was maybe 1/2 -> 3/4" higher.

- This level of expansion is normal right?

Tuesday I checked the level again (cold) and it was down about 1/2" from the seam...looked under the hood and noticed that the starter had some wetness to it, felt around the heater control valve and it too was a little wet... New heater control valve received today from fcpgroton and it's going to be installed tomorrow. I also noticed some coolant drops on the plastic radiator ends, they were apparently coming from the junction between the metal/plastic. Haven't seen any drops lately, although what looks like light gray dust does accumulate on the "plastic reinforcment ribs" (not sure how to describe them), I brush them off every other day but they come back. Could this be dried coolant or is it just regular dirt accumulation from driving?

The car doesn't overheat, the temp guage runs at the 12:00 position. Although on a long (3hr) leaf-peeping trip the guage would drop down ever so slightly but enough to notice. Haven't driven the car much since then (two weeks ago) to notice any movement.

So my question(s):
- If there is air in the system, does it bleed off somehow automatically?
- Would an air bubble in the system cause the temp guage to fluctuate ever so slightly?
- Would an air bubble increase the pressure in the system to the point where leaks may pop up?

In any case, after hearing about the plastic/metal radiator failing, I plan on replaceing it with an all metal one. The heater control valve is coming out tomorrow (or maybe late tonight when the wife gets home...).

Thanks for listening,
Zuda