I''m perplexed by this slow leak, its definitely not getting in to the oil or exhaust. Yesterday, I finally noticed a small coolant puddle under the rear of the engine while the car was sitting in the driveway warming up before being driven way. There was some dripping coming down when I first saw the puddle, but it stopped after the car completely warmed up. Today I put the car up on ramps and let it warm up while I kept an eye out for any leaks. Sure enough, as the engine started to warm up there was some coolant dripping off of the lip of the transmission oil pan, which like yesterday, eventually stopped. I had a pretty bright LED flashlight to look for where it was coming from above the tranny oil pan, could not see any thing leaking. There was a small drop of coolant on a plastic wire loom that was anchored just above the oil pan lip, but nothing obvious as a source for where any it was coming from.
I am going to put some florescent leak trace dye in the coolant to see where its coming from. Tried to buy some at Advance Auto, bit the product info on the bottle said it was not for use with GM Dexcool...Anyone know of a what product is compatible? Or where leakage onto the tranny oil pan might be coming from? All the areas carrying coolant near/above the pan appear perfectly dry , including the hoses going to the heater core bulkhead penetrations. I don't think it could be a leak of the tranny oil cooler, the transmission fluid on a dipstick check looks totally normal, and the fluid level level is normal. Over the last month of so I have put in a close to a gallon of makeup coolant, I would think if it was getting into either the engine oil or tranny fluid, I would surely see some signs by now. All I have is some evidence of a slow external leak that apparently seals up as the engine heats up, and its not from any obvious place. The leakage only while heating up seems to be consistent with me up until yesterday, not seeing any leakage under the car - I usually start up the car and drive right off, so most likely any warm up leakage up until now has not been able to collect under the car. Everything in the usual places I can see for such a leak are perfectly normal looking, including the radiator, hoses, water pump, overflow tank, and hard piping and hoses. I'm really not seeing any more leakage on the front of the engine where I did see a few drops onto the starter from somewhere above it last week.
