Well - unfortunately although I've just had the water pump replaced along with the attached hoses, etc - last night on the way home I got the "Coolant Level Low" message again on the dash. After I left the mechanic I'd checked the coolant level to see where we were at and this morning, with a cold engine I checked once again and sure enough, it's right below the lower fill line. (EDIT: Car only has 60k miles on it in case this impacts one way or another)

The odd thing is, I don't smell anything this time. Before I did smell a bit of antifreeze but now there is no odor that I could detect. But either way taking it back to the mechanic today, is there anything specifically I should ask about or ask him / them to do or perform?

• I know some of you said the pressurized test in other threads and I think they might have already performed this but going to double check
• I also saw some people said the fluorescent dyes test with the UV light
• I know some of you mentioned a floating sensor inside one of the reservoirs but this would only indicate a faulty sensor and not an actual leak if memory serves me right.

Would there by any kind of residue on the cap to the reservoir itself if that's the leak? Anything else you can think of?

FYI - I tend to drive it in dynamic sport mode when I am on the highways, is this something that I'm not meant to be doing every day?

 

Nightshadow, like you have mentioned, the best thing I can thing of is to get a bottle of the dye, put it in the coolant, drive the car for say 5 miles (mix the dye into the coolant). From there, let the engine cool and then pressurize the system with an external pressure source. From there, start running the black light everywhere. Odds are, you are going to find that the leak is from the connection on the back of the water pump and it is gathering on top of the engine in the V. You will see it run out the side of the V and around the water pump. If you pressurize the system and don't see where it is leaking from, this leaves 3 possibilities. 1) bad head gasket, but this normally causes gases to go into the coolant, not the coolant into the cylinder, but you can see a white cloud normally on start up (not the whisper from normal exhaust, this will be pretty obvious; 2) bad heater core, but you should be smelling coolant inside the car, 3) bad relief valve/cap to your overflow bottle (this could be proven by simply putting the cap back on, going for say a 20 miles drive and then shining the black light around the overflow bottle.

Like you said, a bad level sensor will not cause a loss of coolant. So, you can rule that out.

If you are going to have a leak, based on the age of the car, you are going to see it either: 1) at the water pump, 2) on the edges of the radiator where the various parts join together, or 3) a pin hole leak in one of the rubber hoses.

 

Thank you for the extremely thorough breakdown. The dye can be any brand right? So long as it's made for this purpose. Or are there dyes that only interact with orange coolant vs green one, etc? I ask because I found one by GM AC/Delco for like 8 bucks I'd like to get.

 

Nightshadow, the dye should be universal. Take a look at the label and make sure that it doesn't say something to the effect of "can only be used with ......".

If you are going to do this at home (you can normally rent the pressure tester from your local auto parts store for free, just have to put down a deposit), I would say to park the car with the noise slightly down compared to the rear. If you have a leak on the back side of the water pump, you don't want it running out the back of the engine and sending you on a wild goose chase.

One other thing, you may want to do an initial scan of the engine bay with the black light to see where the dye may have already been splashed during your short drive. Again, this can send you on a wild goose chase (trust me). Granted, if you see it making a nice ring around the whole engine bay, then odds are you are looking at a water pump issue as the water collects in the V of the engine and then when it comes out, it drops on to the water pump pulley and gets flung around.

 

jaguar coolant has a trace dye in it. Why I love it and use in my jaguars, Chevy's, and Nissan. Was the reservoir really low or did the float inside sink and turn on the light?
Still have the outlet pipe under the intake and heater outlet pipe on the back of the engine which are leaks sources as well. Sometimes you fix 1 leak to have another start once you fix 1 leak and make the system tight again. Why I always pressure test the system again when I finish a cooling system repair.