coolant res holds pressure great but still losing a ton of coolant
 

I have a 98 S70 GLT and i am leaking a ton of coolant. I found that I had a crach in the res where the return hose connects so i puut on a new res and cap.

I pumped it to 4psi and it hasnt lost any pressure in the past 40 minutes. i still have the pressure tester on there as i type this

Any ideas? I took the belt guard off and the water pump didnt seem to be leaking (i only popped off the plastic guard right bty the coolant res.

other pic

I can't tell for sure what sort of fluid that is in your pictures - the locations and overall appearance don't make me think "antifreeze!" however.
Whenever an S70 is losing fluid (and there isn't a puddle under the car) I suggest that you start feeling the carpet and sniffing your defroster vents.
Then pull your dipstick and see if your oil has been fraternizing with coolant.

It's definitely antifreeze. I do have a slight oil leak, but i only have to add a tiny bit every month.... coolant on the other hand, if I were to drive 2 hrs on the highway it would be bone dry. On the other hand, if the car just sat still for a week, I would lose very little coolant. That is why I thought I should do a pressure test.

I did check the heating core and that was fine, also there is no fluid under my carpets

I do sometimes smell antifreeze when the heat is on (havent had the A/C on since the leak stated) but that is (i think) because the steam from the antifreeze gets sucked into the vents

i don't know where to look now

you've got to put in more like 12-15PSI to find the leak 4psi is nothing to the coolant system.

were you losing coolant or power steering fluid? There is an odd noise when I turn the wheel all the way to one side like parking

I was worried about pumping the res too high. Are you sure 15psi though? that seems high, i thought 150kilograms/sq meter (what it says on green cap) was ~3.1 psi? i was worried to pump it to even 4psi

I wasn't loosing much of anything. If you run dry in 2 hours it's going somewhere. I'll check pressure tonight when I get home. I hope you arent burning it.

My tank says 150KPa which is kilopascals. Converts to about 21 psi. Most cars operate in the 15 psi range

Also it doesn't take much fluid to make a huge mess under the car. When you pressurize the coolant tank look everywhere. You are pressurizing the entire system not just the tank. If you pump it up to 11-15 psi and it drops quickly and you don't find the fluid it could be going in the oil or the cylinders.

Thanks man, hopefully this will lead me now to the source of the leak. Im going CRAZY searching for it

Also want to pressure test a cold engine; will naturally lose pressure as the engine cools. And 40 minutes is nada.

Pump it up to 15 psi on cold engine and let it sit overnight; if your pressure has dropped by the AM and you don't see any puddles under the car or in the cabin, pull the plugs and crank the engine over to see which hole makes like a geyser.. :eek: