Hi All! In reading through here it looks like you've beaten up on the cooling systems pretty well. However, I have not turned a wrench in a while and I have some concerns regarding my C70's cooling system.

For quite a while (starting in 2010) my daughter and I noted that when we ran the A/C we would lose coolant. I replaced the cap on the expansion tank - that didn't seem to help but I could see no leak. I checked the oil - no visible signs of oil/coolant mixture, no unusual emissions from the tail pipe and the temp gauge never went above level. Didn't worry about it too much....

Fast forward to October 2012 - The day was unusually humid so I had to run the defogger in the AM and the AC in the afternoon as the day got hot. Sitting at a light when steam/smoke the sickly sweet smell of coolant and temp gauge rockets to the red zone. Fractured radiator was the culprit - they're PLASTIC???? Had the rad replaced. Did fine through the winter but as the weather warmed up (we're in 2013 now) started losing coolant again. Simple fix - the expansion tank was shot - small cracks in the outlet fitting - all sounds familiar right?

Replaced the tank in May, 2013 - all was right with the world until June 2013 when I ran the AC - got home to find that the seam where the top of the tank fits to the bottom has failed and it's merrily spewing steam/coolant. Convinced the parts store it was defective & just replaced the tank this weekend -doing great so far. However, I am scared to death to run the AC. Was it just a fluke that I got a bad tank replacement?????

Now, I am convinced the water pump is OK as the fluid in the expansion tank warms up as the engine warms up. Logically - if the pump wasn't working the coolant would not circulate and the tank would stay cool - yes? No? There is still no sign of oil/coolant mix, no smoke from the tail pipe. What else can I check, how can I check it to see if I have a potential blow out on the horizon from over pressure in the system? How firm should the rad hoses be at full temp? Is there anything I can do to check and see IF the pump is OK without taking it off? When the car is off and at operating temp (i.e. just got home from work) should the coolant try and boil out when I loosen the cap?

Is there ANY logic to running the AC (by the way - NOT sitting in traffic - avg speed about 45) causing the cooling system to come unhinged?

Long post - thanks for staying with me!

 

Hey, thanks for the help! Seriously. NOT.

 

Hey, sorry nobody replied before now =/ Haven't been on the forums much until recently. I have had a few problems similar to you, cracked expansion tank, etc. I feel like they are just poorly designed/manufactured. I almost want to make my own out of aluminum or something. A good way that I've heard to check your water pump is to squeeze the radiator hose while the engine is running. A good pump will build up pressure in the hose, and when you let it go, you should feel a rush of fluid, much like you would when you crimp a garden hose. Like with all rubber hoses in the car, you should be able to squeeze them closed with your hands, but if it is really easy, then they need to be replaced. These cars don't seem to boil coolant like others do, they just kinda pressurize the tank (at least in my experience with them). I also don't see any correlation between the A/C system and your coolant issues, although I'm not a mechanic (I do all my own work though ><). I hope you are able to use some of this advice!