Rbeasy

01 Sport, bone stock. Started to see coolant spots under the hood driver side. This is after a 8 mile in town trip. Hoses, connections are clean as a whistle. Water pump and thermostat body show no signs of leaking. Honestly cannot find any leaks, seeps etc in the engine bay or under the car. Does not run hot, elec fan comes on when it should. Replaced radiator cap. Had shop pressure test coolant system back in February and it holds pressure like a champ. Since then the spots have appeared. If it wasn’t for the spots under the hood or on the power steering idler arm adjuster bracket you would know any thing is a miss. Comments, pot shots or ridicule is appreciated!

robsjeep

So you say that no leak before the shop testing cooling system, leak happened immediatly after the shop work, correct?

What pressure they take it up to for test? Did they spill coolant, thus causing an apparent but not actual leak?

Leaks can be elusive to find. take a clean white paper towel, fold or tear to size and run the edge of the towel around each near by cooling hose at each fitting, and each hose clamp. many leaks happen here. hose often gets small hard to see tear at hose clamp, and it drips away slowly under pressure, you got to remove clamp to see it sometimes. anyway by dragging the towel edge over hidden surfaces behind things where you cant see, you can examine the towel to see if it soaked up any green color, i.e. coolant A coolant is getting on the belt and or pulley for sure. also run a bit of towel around the water pump behind its pulley, around shaft, and weep hole, see if it comes back dry or not.

You may have to loose hose clamps , move them a bit to see if hose is torn, or split. this can happen with old hoses, a hidden little tear or split at the clamp area.

good luck

Rbeasy

Spots under hood appeared sometime after pressure test. They ran it to 16psi and it held steady for 15 minutes. They repeated the test with same result.After I noticed the coolant spots I cleaned the engine bay. Spots still occurred with no visible sign of leakage. Drive about 6 miles and did the paper towel test. All hoses and connections were clean. Got underneath the thermostat body and found some wetness! Would make sense this could be the culprit as a leak under pressure would cause the radiator fan to blow drops up to the hood. So for fun I’m going to splurge on a new thermostat body and thermostat and see if that solves this weeks mystery.

lawsoncl

You gotta have a major leak to see any drop in pressure in 15-minutes. Pressure testers are great for pumping it up and looking for the leak with the engine off. I wouldn't rule out a pinhole leak in the radiator.

robsjeep

good, you found a leak, be sure to double triple check the hoses at thermostat, remove clamps, inspect hose ends. soft hoses are also bad. my elusive leak ended up being a small weep of a leak around a heater hose end at thermostat. also a housing might leak, odd are higher that it is a hose end, and those hose leaks can be really sneaky and hard to see.

good luck