Losing coolant through the overflow pipe of the reservoir

[EBELLE]

Hi guys just bought a avensis2007 t25 2.0. I'm noticing coolant going out of the over flow pipe from the reservoir. Can some body give me some advice about this issue please

[Bper]

Hi Gerald,The most likely reason coolant is overflowing from your reservoir is either a faulty radiator cap or an issue with the thermostat. Over time, the radiator cap can wear out, which means it doesn’t hold pressure like it should. When that happens, it often pushes coolant into the overflow reservoir and then out the pipe.

Another possibility is the thermostat isn’t fully opening. If that’s the case, it restricts the flow, which can make the engine run hotter than normal and build up pressure forcing coolant out of the overflow pipe.

Both of these fixes are fairly cheap and easy to try. I’d start with the radiator cap and thermostat, and if that doesn’t sort it out, then it could be worth looking into other things, like a possible head gasket issue or a blockage in the cooling system.👍

[Heidfirst]

another possibility could be a head gasket failure. Any signs of overheating?

Which 2.0, petrol or diesel?

[Paul Gailey]

i'm having the same issue.

Mr T today said a hissing overflow cap indicated excess engine pressure and quoted me €1000 12 hour task to tear down the engine just inspect the head gasket.

I asked them to do a pressure test to inspect for coolant leaks and they did not confirm they had completed that or done any sort of sniff test. 

My oil is not milky and is only 1500km old, the car just did 50mpg on a 800km trip in a day last week and it pulls fine, so I'm puzzled.

I did a rudimentary test of adding a few drops of dipstick oil onto foil and blowtorch heating it underneath to see if any fizzing evaporation occurred to indicate coolant mixed in the oil. Result was negative.

Very occasionally there's white tailpipe smoke but the coolant temp level never exceeds the horizontal mid point of the dashboard gauge.

Is the thermostat easy to access? if yes, i'm tempted to check/replace that.

204,000km on the clock, I'm minded just to keep topping the coolant when required as the engine inspection fee alone is too high relative to the resale value of the car.

 

[TonyHSD]

Air locked along the cooling system can and usually cause exactly the same pressure built up. 
When changing coolant or any part on the system like water pump radiator or thermostat it is very important to follow procedures to bleed the system. 
Before draining the system the hvac settings needs to be in manual mode AC off, with heating selected at highest temperature settings fan speed 2. 
After filled up with new coolant start up the engine and let it run for 20 min with tank cap open and add coolant as necessary to keep at max level, double check hvac settings are high heat and speed two in manual mode and wait until engine reaches 95C° the thermostat should open and coolant should flow through second loop , you need to top up again and watch for radiator fans needs to kick in and spin fast. Keep an eye on engine temperature to prevent an overheating if anything fail. Can use a diagnostic tool or app to monitor temperature. 

[Heidfirst]

2 hours ago, Paul Gailey said:

i'm having the same issue.

Mr T today said a hissing overflow cap indicated excess engine pressure and quoted me €1000 12 hour task to tear down the engine just inspect the head gasket.

I asked them to do a pressure test to inspect for coolant leaks and they did not confirm they had completed that or done any sort of sniff test. 

My oil is not milky and is only 1500km old, the car just did 50mpg on a 800km trip in a day last week and it pulls fine, so I'm puzzled.

I did a rudimentary test of adding a few drops of dipstick oil onto foil and blowtorch heating it underneath to see if any fizzing evaporation occurred to indicate coolant mixed in the oil. Result was negative.

Very occasionally there's white tailpipe smoke but the coolant temp level never exceeds the horizontal mid point of the dashboard gauge.

 

your car (still a T180?)

a) the early AD series are known that they could develop/have head/head gasket issues - Toyota replaced quite a lot of engines foc. Long threads on here about it.

b) has a DPNR (glorified DPF) so the white smoke could well be regen.