MustangMike

I have a '97 3.4 SR5 auto with 144,000 miles on it. Yesterday, in mild heat, after about 15 miles of driving it boiled over on me - more specifically, through the overflow tank. Luckily I just pulled in the driveway and had noticed the temp guage about a 1/4" away from the red line. Backed up a bit and saw the dreaded puddle on the driveway. Opened the hood, and found coolant boiling through the overflow tank and I could hear it boiling inside the rad as well.

Some history - replaced the timing belt and water pump about 30k miles ago and flushed coolant (50/50 mix), new T stat, hoses, etc. No problems since then, though I've noticed slight coolant usage in the last 10,000 miles or so (visible through the overflow tank being slightly lower over the course of several weeks). Within the last 7 or 8,000 miles, I've noticed a minor coolant smell (outside of the car, not from the heater core) just after shutting down and when idling. Best I can tell, the rad may have a few small pin holes - there look to be 2 or 3 SMALL wet spots, not enough to drip at all though. Within the last 2-3,000 miles, noticed VERY slight drip where the lower rad hose connects to the T stat neck, close to the block. Attributed it to weak hose clamp that I didn't replace earlier.

It's been running great, and yes, I tend to drive it hard. No cooling issues up to this point. Car has always had normal maintenance done on time and by me personally. Outside air temp yesterday was about 80 degrees or so and I was driving around town.

In my search (in the dark) last night to try to find something I noticed two things. First, fan clutch seems to be worn, if not shot completely. The fan spins very easily after shutting down and engine is up to temp. When shutting the car down, it actually continues to free wheel for a few seconds. Second (and what concerns me), with the rad cap off when cool and then running the engine and bringing it up to temp, the coolant does not visibly flow by along the top of the rad core (below filler neck). It remains still and slowly begins to 'bulge' up as the temp increases.

So I figure I should at least replace the rad (with the small holes) and the fan clutch - both are the originals. Any other ideas as to what's up? Should I be concerned about a head gasket problem? Water pump came from the dealer, so I can't imagine it's failed already with only 30k on it. Hard to believe the T-stat may have failed already too, though I may have picked it up from a parts store as opposed to using OE part.

Thanks for your help, sorry for being so long winded!
Mike

Caffeine

what's your oil look like?

MustangMike

Forgot to mention - oil looks and smells fine, as does the ATF.

MustangMike

also, no smoke that I noticed and it starts up, runs and idles fine - no issues.