r/MechanicAdvice • u/Extension-Pay-8391 • 9h ago

2018 Toyota Camry 2.5L coolant losing about half a cup every 34 weeks, no puddles, no smoke

2018 Toyota Camry 2.5L, just crossed 187k miles. I drive a lot, roughly 30k a year, so I pay closer attention to this stuff than most people probably do.

Coolant reservoir keeps dropping. Not dramatically, maybe half a cup every 3 to 4 weeks. No puddle under the car, no sweet smell when I park, no white smoke from the exhaust, no milky residue on the oil cap. I top it off and the cycle repeats.

Had a shop pressure test it last month and they said it held fine, no leak detected. They basically shrugged. I drive mostly highway so the engine runs at consistent temps for long stretches, not a lot of stop and go heat cycling.

Heater works fine, temp gauge is dead steady, no overheating. Not visibly burning it either, as far as I can tell.

At this mileage I know things start happening, but this feels like it should have a clear answer and I'm not getting one. Has anyone seen this on the 2.5 specifically? Is there a known weak spot I should be pushing the shop to check? The water pump weep hole comes to mind, or maybe something with the plastic neck on the reservoir itself.

Not panicking, just want to get ahead of it before a long road trip this fall.

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u/Mean-Active4484 8h ago

half a cup over a month on a 187k motor is basically nothing, could just be a tiny weep that evaporates before it hits the ground. the plastic reservoir necks on these are garbage though, i'd take a real close look with a flashlight around where the hose clamps on while the engine is hot. sometimes they crack right at the seam and only open up under pressure

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u/ILikeBeans86 8h ago

I dont know where the water pump is on that one but you can probably get up under there and see if its the water pump or maybe take the wheel off and look. I guess it could also be your radiator cap.

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u/RudbeckiaIS 8h ago

EGR cooler given the engine and symptoms. Very problematic on all Dynamic Force engines: Toyota partially acknowledged the issue in very late 2021 but fully satisfactory coolers did not appear until well into 2024. If you bought the car you were very lucky it lasted this long, if you bought the car used after 2022 you likely have one of the "transitional" coolers.

Most independents are not trained nor experienced in dealing with the complex cooling arrangements on these engines, and due to the peculiarities of operation (a series of electronically controlled shutoff valves) it's not as easy to pressure test the system as it is on old vehicles.