02 Park Ave, losing small amount of coolant

02 Park Ave 180,000 miles. Noticed an antifreeze smell when car was hot and parked in the garage, checked the coolant reservoir and found it to be low. Had to add about a quart of coolant to bring tank back to normal level. I see some wetness under the throttle body area but don't see the leak source. I am not getting coolant puddles under the car. Bypass elbows replaced this past summer. Is this an indicator that the upper or lower intake manifolds / gaskets have reached the end and will need replacement?

Look closely with the aid of a good light and telescoping inspection mirror. You may be able to see if the leak is at the throttle body, thermostat housing, coolant temperature sensor, or intake. They all can cause coolant puddles in that area.

I had a leak under the back of the TB (by the air inlet) in vicinity of the EGR stem. This was due to, I reckon the vehicle being in the garage on blocks for an extended time.. when the seals must have become brittle.

Anyway.. the approach was to use Spray 9 (which is highly alkaline) as an engine gunk remover. Spraying under there in a stream, it took off pretty much all the crud and leakage from the area, which allowed to "keep an eye on it." Soon after I did notice a leak under the TB area with a LED flashlight, etc. Degunking made it easier for the mechanics to inspect and quote the job too.

After a "double gasket job" I still smelled coolant when pulling in the garage. Turns out the upper radiator hose flange gasket also had a leak. The shop fixed that as a courtesy, but I still smelled coolant, although faintly. After two back-to-back coolant flushes (make that exchanges), unplugging the reservoir tank hose and douching out the recover thank.. then it really started to clear up.

But there was a slight coolant smell in the garage after pulling it in. LAST step was to buy a new Delco radiator cap (after 15 years on the original) and it's now sealed up well. BTW.. never did add those Delco pellets in the system.. and the coat-hanger tool really worked GREAT for swabbing out the recovery tank.

-Ed

Edit.. the mistake was to skip the coolant change during the gasket job to cut costs. Later, lots of crud and chunks of gasket or sealant were found obstructing the tank hose. I'd image the heater core has some debris as well.

He never responded, but my guess, with a leak in that area, is the throttle body gasket...