How do you fix the coolant resivor that is leaking when you shut off car but no overheating

Hi Anonymous.

The answer will depend on the other details. It may be leaking from the reservoir when the car is running as well, but be harder to see since you will be moving rather than forming a puddle.

1. If the fluid is all the way up to the top of the reservoir and leaking out around the cap, then you're either overheated, or you may have air in the coolant that is expanding and pushing coolant up into the reservoir. You can look up 'How to Bleed Radiator' for your make and model and see if that makes a difference.
2. If you bleed the radiator, and then end up with more of the same, and more air/gas in your coolant, that can, unfortunately, be a sign of head gasket problems. It would mean that high pressure exhaust gas is leaking through the head gasket and into your coolant. If that's the case, you'll want to get your compression checked, and contemplate the cost of the repairs vs the age and value of the car. (if the head gasket is going, you'll likely as not need to redo the valves and the piston rings at the same time. otherwise the restored compression from the new gasket may just send those components over the edge that much sooner)
3. If it's not that sort of air in the coolant, then Fixes will depend on your vehicle. You can:
   1. Make sure the reservoir lid is on tight
   2. See if there is a gasket (or perhaps only part of one) in the lid/cap. if the gasket is shot, it'll let fluid leak.
   3. Make sure the reservoir isn't over-filled. There will be a fill line. The coolant should go no higher when the engine is cool. It needs some space to expand when the engine runs.
   4. Spray the reservoir with some simple green or other cleaner, and wipe it dry with paper towels. Give it a short drive, then stop, turn the car off, pop the hood, and feel for dampness around the reservoir. An actual physical crack or hole in such a reservoir isn't all that likely, but it can happen. if there is one, you'll need to replace the reservoir.
   5. Akin to #4, feel at the joints where the hose(s) attach to the reservoir. If they are damp, check the hose there for wear or damage, and make sure that the hose clamp is in place, and is tight. Work your way down the hoses and see if they start getting wet part-way down. If so, then there's likely a leak there, which means the hose should be replaced.

1. Don't work on the car with the engine running if it can be avoided.
2. Try not to work on the car with the engine compartment hot from extended driving. it's easy to singe yourself on really hot metal.
3. You're working around potentially hotter-than-boiling-water coolant here. Wear gloves and eye protection. As someone who was once thoroughly doused with said scalding coolant when a hose on a rebuilt Chevelle SS popped loose, it really sucks and hurts like *(&^^%%%. Eyes would be a lot worse.
4. Coolant is also toxic stuff, which underscores wearing gloves. IF you have to drain things to replace parts or bleed the coolant system, please use proper buckets and pans and take waste coolant to a proper disposal spot - most auto parts stores will accept it. Animals tend to think it tastes sweet and aren't put off by the color, and it'll kill them painfully, so please help the neighborhood pets and birds. stay happy too.