Thanks for the offer. My schedule is off/on but am definitely very interested. PM sent.

I took the car to the shop this morning around 9am. Tech saw the coolant level, and was perplexed about the coolant level below MIN, just above the "996 marking." He didn't know what could be causing the coolant drop. I asked him if there are any loose hoses during the water pump install, and again asked him about coolant reservoir cracks or radiator leaks; he again didn't think they were issues b/c he hooked the car up to a pressure test and found no loss of pressure.

He advised to top the coolant for now, and return Mon for more diagnostics if need be. Said something about hooking up the pressure to the car overnight and see if it develops any leaks.. So he topped it off with distilled water in front of me.

I couldn't tell at what level then b/c the water and coolant wasn't mixed together, just that is was somewhere halfway above MIN and below MAX.

I drove off to the office shortly after and popped the engine hood. So I checked the coolant level then, saw it was halfway between MIN and MAX. After leaving the office, I did a series of drives/errands. I really began to get a feel for the car and pushed it to 4-5k rpms in 1st/2nd gear. Each time I popped the hood and unscrewed the cap, and so far so far good, coolant levels haven't changed. Each time I unscrewed the cap I noticed how hot the coolant is and the "hiss" release. Probably checked coolant and unscrewed the cap 6-7 times (which may have cause more air pockets).

So I drove the car quite a bit today, and parked it in the garage around 2pm. Coolant still between MIN and MAX. Car is now sitting in the garage. I let the car sit undriven now for rest of the day.

At 5pm the engine has cooled down quite a bit. I checked the coolant level again. It probably dropped very SLIGHTLY but still midpoint MIN/MAX. No leaks or puddles on the floor (except puddles of rain).

At 10pm, I checked coolant again, engine is now cool to touch. Coolant level has dropped again below midpoint of MAX/MIN but still well above MIN. I am now suspecting this drop may be due to the colder engine temperature and coolant now contracting due to the cooler temps.

So my thoughts are this:
1) After the tech did the water pump and coolant flush, there may have been lots of air pockets in the coolant system. Hence the initial drop of coolant.
2) Going off on a whim I suspect the tech forgot to top off the coolant a few days ago when I took the car in letting the shop know of the low coolant.
3) When the tech topped of the coolant this morning, the engine was at >180 degrees. Coolant has already expanded. After the topping off this morning and the vigorous drives today, coolant levels didn't change. So at 10pm when the engine/coolant is cold, coolant level dropped due to coolant properties.

At 10:10pm now that the engine is cold, I topped of the coolant w/Prestone extended life coolant. It's now near MAX. I'll plan on driving the car through out the weekend and monitor the coolant levels when the engine is hot and cold without taking the cap off, and with the pressure the relief valve UP as suggested by a member here to purge off any air pockets I may have caused by opening the cap constantly.

I'll keep the thread updated. Here's hoping this case is just a big misunderstanding due to air pockets and not adding coolant when engine is cool.

 

If your tech pressure tested the coolant system when the car was cold it may have very well held pressure.
What happens in the case of a radiator weep, when cold there is no expansion due to no heat soak. Once the radiator gets heat soaked they expand causing a weep at the tank and rad crimp.
Not to say this is your issue or there is an issue since no coolant drop has been noticed recently, if you continue to smell coolant after a heat soaked coolant system use your nose as previously described, and check at the radiator vents on the front bumper, if noticeable you have weepage at the rad. Good luck

 

Update again: I've been driving the car for nearly 3 straight days now since I topped off the expansion tank when it was cool, and the coolant level has been constant. Coolant level is definitely higher when the engine is hot (ie. temp is slightly greater than 180F) and lower when engine has a chance to cool down.

Will keep this thread updated in about a week so there's some closure. Learned quite a bit for future reference on where to check if there's definitive proof of coolant leak... But as of now I'm suspecting the initial drop in coolant level was due to rampant air bubbles and topping off the coolant when the engine/coolant was hot.

 

Sounds like you're in good shape to me any further information on the smell that you were getting?

 

No further insights on the smell unfortunately. My kid has described it as a "burning smell." It's a little more prevalent when I drive up my inclined driveway, so I'm wondering if it's just me riding the clutch a bit b/c I have to slowly crawl into the garage.

Btw do you have any tips on how to slowly inch the car into a garage or up/down a incline/decline when parking? I usually have to feather press/depress the clutch and gas together to get the car moving ~3-5mph without it stalling.

 

I guess it depends on how steep your incline is for what is the best method... Mine isn't really steep, but I have to come off of the street slowly and at an angle to not scrape on entry and exit. I just slowly slowly release the clutch without using throttle. If its really steep you may have to give it some throttle.. I'd just try to hold it steady rpm and very very slowly ease out the clutch. If I'm on really steep hills driving about town I use the handbrake to hold the car so there isn't much additional stress put on the clutch when taking off. Not really a one-size fits all method to do it, its more situational.

 

Hopefully you are not slipping the clutch to much, you will shorten its life and have to pay the man!