204ps BiTDi engine coolant under pressure when cold - help required

[c_paul]

Hi All,

I have a weird one that many of you many be able to help with if you have a moment.

Is it normal for the coolant system on a 204ps BiTDi to be under pressure when cold?

If anyone has one, that is cold, and could spare me 2 minutes of your time, could you please take the coolant cap off and see if there is any pressure there?

I have a 2016 and think the head gasket or cylinder head has a small pathway to the coolant circuit but the dealer thinks otherwise. Main symptom is coolant under pressure when cold. Was losing coolant and has had the egr replaced but it is still losing coolant and is still under pressure. Garage claims residual pressure is nothing to worry about.

This is getting very expensive.

Thanks,

Chris

 

[Bundy88]

Hi Chris,
My 2022 204ps is cold and has no noticeable pressure...11k miles on the clock.
Cheers
Al

 

[DXX]

If there is no detection of combustion gases in the coolant system it could be a very small crack in the charge air cooler that seals when the induction system returns to atmospheric pressure when the engine is stopped.

 

[Dellmassive]

The coolant system needs specific procedures to bleed out properly..

Running pumps in specific secuence, from diagnostics kit.

So you may have an airlocked system?

 

[RobertO2023]

“Dealer says residual pressure is nothing to worry about” I heard some cr..p in my life from dealers but that’s rubbish. Get a knowledgeable technician to undertake a sequence of tests to determine why residual pressure exists. You mention still losing coolant which could point towards a head gasket but that would show contamination in the coolant. I would start by releasing the pressure from cold and doing a cold engine reverse pressure air test over 12 hours.

 

[c_paul]

Update Jan 25: in case anyone sees this… so the egr was replaced. I don’t think the coolant is going down any significant amount - I haven’t topped it up for over 5k miles.

I think there is air in the system somewhere and air is getting in. After a long journey I let it go cold and then release the pressure in the system and the level goes up in the coolant tank with bubbles gurgling back up to the tank.

Not happy but not causing me too much trouble.

Other than the inconvenience, only issues are the rear heater doesn’t heat and I am worried the over pressure will cause premature failure elsewhere.

My current theory is still hairline crack in head or head gasket.

 

[RobertO2023]

It does seem to point to head gasket problem or possibly a cracked head. There should be no pressure in the cooling system when the engine is completely cold. If the rear heater has stopped working after a drain down that would suggest it has not been properly bled through and air remains in that part of the system. I hope you get it resolved.