Coolant problems Yaris d4d 1.4

[nikolica1981]

Hello everyone, I'm new to this forum
I recently bought a Yaris verso d4d 1.4 2004 model with 92k km
I find regular coolant leaks on the expansion tank around the plastic cover
I hope it's not a blown gasket
What I would like to ask is if anyone has a similar car and can check for me
Whenever I open the plastic cap of the expansion bottle, there is pressure in the system even if the car is completely cold, ie. early in the morning.
I would appreciate any comments and help
Thank you

[Bper]

Hi Nikola,The cap might be the problem sometimes the expansion tank cap doesn’t seal properly, which can cause leaks and lead to a pressure build-up. Plastic tanks can get old and develop cracks, which might be where the coolant is leaking from.

Give the hoses connected to the expansion tank a look.They could be loose or worn out.

I know this may sound concerning but its another possibility that you may have a blown head gasket, it can let exhaust gases into the cooling system, causing pressure. Just keep an eye out for any coolant mixing with oil.
If the thermostat is stuck, that could lead to overheating and extra pressure, which might also be causing leaks.I would start with the easy stuff first, like checking the cap and the tank.👍

[Madasafish]

The coolant is pressurised when running  ..Ours  a 2003 model -has residual pressure even after 24 hours unused... so it is normal.

Watch for oil in water - mayonnaise looking - sign of head gasket failure..But yours is a 2004 when the problem had been solved - in 2001 or 2002

A failing pressure cap would mean your car might overheat. I suspect either a cracked  coolant tank, or a failing pressure cap...

But mayonnaise - white deposits under the pressure cap- is a sure sign of HG failure - oil in water.