Q: my car leaks coolant but is fine with water. it also recently had a new water pump and thermostat put in why would this happen?

asked by on September 07, 2017

when i bought my car they said they had just replaced the thermostat and water pump. It overheated the same weak and all my coolant leaked out. I put water in it then i had it flushed and refilled with dex cool and now everytime i put coolant in it it leaks but when its only water it holds better and leaks less. Why would this happen?

My car has 140000 miles.
My car has an automatic transmission.

Coolant is leaking Inspection $79.99 - $99.99 Get a Quote

You are probably just seeing "randomness" in the leak rate when you add water versus coolant; both will leak at the same rate. What you want to do, of course, is just simply get the leak pinpointed and repaired. If the cooling system leaks, it obviously will not hold maximum pressure either and the coolant will then potentially boil over and that itself creates overheating (pressure in the sealed cooling system RAISES the boiling point of the coolant). Engine coolant can leak externally through a hose, radiator, water pump, etc. or internally due to a leaking head gasket and sometimes a leaking intake manifold gasket depending on the engine design. External leaks are typically found by simple pressure testing of the cooling system. To find the leak that exists in your case, and get the required repair estimated, please request an engine cooling system leak diagnostic and the responding certified mechanic will get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing


Experienced Mechanic?

Earn up to $70/hr

What others are asking

It started over heating yesterday... didn't notice any leaks at the time. Today I put antifreeze in the reservoir because it was a little low ran to the store 3 miles away and it over heats again. I turned the heat on high and hot and it was blowing cold air with no condensation anywhere. Got home and it is leaking somewhere next to the firewall but I can't see it. So is it a radiator hose?

p0340

Some of the common causes of Diagnostic Trouble Code P0340 include camshaft position sensor circuit wiring that is broken, shorted, or corroded; a camshaft position sensor circuit connector that is broken, shorted, or corroded; a faulty camshaft position sensor; a...

Radiator hose rubbing pulley after minor accident

Thanks for inquiring about your vehicle. A collision specialist needs to examine the vehicle and YourMechanic does have specialists who could perform a mobile examination and arrange repairs. To save you some money initially you might attempt to contact a...

Car will not start, only clicks once or twice.

Hello. Clicking when you turn the key is usually a sign that there is not enough power for the starter to fully turn. If your battery is new, then that is likely not the source of the problem. I would...

Leak around the crankshaft seals

Hello. This is a simple yet involved fix. The crankshaft seal is located behind the crank and timing belt cover. In order to complete this repair, it is necessary to remove the timing belt and timing belt cover, in order...

Brake pedal has no resistance

This is a very dangerous situation as the braking system is one of the most important safety features of a vehicle. Have a brake inspection carried out by a qualified technician such as the ones here at YourMechanic to look...

Car initially fine after cleaning injectors.

The rotary engines have twin rotors that have what is called apex seals the give these engines the compression to run. These seals are a known failure that can cause no start, low power and fouling of the plugs. You...

Alternator not charging the battery.

It is possible that the new alternator may have gone bad as well. From time to time new parts can be bad. There could also be a problem with the fuse in the charging system. I would ask for help...

How do I adjust the auto light sensitivity?

When your headlights are in automatic mode, they will come on whenever the vehicle detects that it is dark outside. However, you can adjust the sensitivity of the light sensor by choosing one of five settings: Max (lights will come...

Related articles

How to Buy a Classic Pontiac
Whether you want to buy a classic Pontiac for yourself or as a gift, here are some tips on buying one for a great value.
The Best Used Cars to Buy for Occasional Drivers
Not Not everyone relies on their car on a daily basis. Maybe you aren’t the type that deals with a daily commute, and running from here to there constantly. If that’s the case, you may be looking for a car...
Understanding the Pontiac Oil-Life Monitor and Service Indicator Lights
Car symbols, or dashboard lights, are a car service reminder. The Pontiac Oil Life Monitor (OLM) indicates when and what service your car needs.