2000 Infiniti I30, leaking coolant at an alarming rate. The reservoir goes from full to empty in 36-48 hours, and there is a huge puddle on my garage floor.
I took it to a mechanic that I have been going to for 15 years and completely trust. He said he can’t find the leak. He put the car up on the rack and showed me underneath, and the bottom of the engine is completely dry. He let it run for a long time, still nothing.
Anybody have any ideas as to what I should do next?
Did you check the oil? You may have a leak going into the crankcase.
Park with a piece of cardboard underneath and look up from where the puddle develops. That will lead to the leak. It could be as simple as a cracked expansion tank off to the side. Some cars have the tank under pressure as the top tank on the radiator may be eliminated. I consider you fortunate to have that puddle as a guide. This points away from anything like a head gasket that would be very expensive. Of course it could also be a water pump that can leak intermittently at first before total failure. Keep it topped off until you find it.
I assume he pressure tested it. If not, you can rent a pressure testing kit from an auto parts store (usually for free).
Remove the radiator cap, screw in the pump and start adding pressure. Usually after just a few pumps you’ll hear or see the fluid spraying out.
Since you’re adding pressure while the engine is cold (assuming the car has been sitting) it’s a lot easier to climb around and under the engine bay without worrying about burning yourself.
It certainly seems odd that an experienced mechanic failed to find a leak of that magnitude which leaves a puddle.
It sounds like you may have only checked the coolant level in the reservoir, not in the radiator (and thus the engine). One possibility, as Al Bundy mentioned, is that the overflow jar is leaking, and if so it might be the only leak. This is quite easy to check – put coolant in the jar and watch. The fix would be to simply replace the jar. It’s conceivable that the mechanic wasn’t thinking of this and instead concentrated on the rest of the cooling system. Anyway, cover this base before proceeding. Normal fill level is to the top of the radiator (check with cold engine only) and roughly at the halfway point in the overflow jar (there should be a mark).
If there is leakage from elsewhere, it’s a little more involved. There are some leaks that seem to occur only when the engine is cold, and some that occur only when the engine is hot. The former can be duplicated with a pressure tester, the latter by running the engine.
What I would do is start with a cold engine and pressure test it. If it held pressure, I’d then remove the tester and reinstall the pressure cap, then run it in place. If that didn’t show the leak, I’d let it cool down (leaving it in place) and inspect it while and after it cooled. If it leaks consistently, as your description clearly implies, I don’t see how this procedure could fail.
Geordi’s solution was always to evacuate everyone, then do a shoulder roll under the closing blast door.
What?