Peugeot 207 1.4 8V Ejects Coolant on Unscrewed Cap: Thermostat, Head Gasket & Overheating Issues

Hello. I have a problem with the Peugeot 207 1.4 8V, namely it ejects the liquid when the cap from the tank is unscrewed. When the plug is closed, it keeps the temperature, the fan turns on normally. Two months ago, the thermostat was replaced, now the head gasket was replaced (the head was planed, checked for tightness, valves, seals and valve guides were replaced), the o-rings under the sleeves and the timing with the water pump were also replaced. I would like to add that before replacing the thermostat and the gasket, it was also the case and that is why the gasket under the head was overheated. I checked the flow of the heater and cooler too. I do not know what the reason is, unfortunately, it looks as if there is no fluid circulation on the open plug. Please give me some hints.

There is probably (I'm not sure) that the cooling system is closed, pressurized and after its opening and while it is working, such cases can happen in such a system. I also had a similar case, but with a Fiat, after opening the tank, the liquid "boiled" after a while, the diagnoses were different. The car is still running for 6 years since the case was discovered. It does not overheat, the fluid does not decrease and everything is OK, of course with the container closed.

polo54 wrote:

I have a problem with the Peugeot 207 1.4 8V, namely it ejects the liquid when the cap from the tank is unscrewed.

Or maybe that's not a problem, just a normal thing when the engine temperature is to be above 100 ° C.
In the Peugeot 2008 daughter, and the engine temperature is kept at 103 ° C and in this case, it is normal that when the cap is loosened it will eject fluid.

polo54 wrote:

When the plug is closed, it keeps the temperature, the fan turns on normally

what are you rummaging for?

Too much money, you wanna smash your engine? The cork is to be tightly closed and that's it. The worst thing you can do is unscrew the cap on a hot engine, a sudden drop in pressure lowers the boiling point.

To the author of the post: you did not specify at what engine temperature you unscrewed the reservoir cap.
However, you must acknowledge, if you do not know when you can unscrew the cap, you better not do it - even for your own good.
Colleagues clearly suggest that the pressure system is to be tightly closed.

Added after 2 [minutes]:

To the author of the post: you did not specify at what engine temperature you unscrewed the reservoir cap.
However, you must acknowledge, if you do not know when you can unscrew the cap, you better not do it - even for your own good.
Colleagues clearly suggest that the pressure system is to be tightly closed.

The plug was unscrewed on a cold engine, I know that it does not unscrew on a hot one, so far it is the first engine that I do, so it is, no one has done it yet, and always when I vented after replacing the pumps with the timing, no one did, I know the laws of physics and I know what is going on with the pressure in the circuit and the boiling point of the fluid that is different, please give me some hints and not instructions when I can unscrew the cap, because I know it, in the manual from 206 with the same engine it says that when bleeding the system after replacing the fluid, the tank is to be open, and this is not possible just like that, half a minute and the fluid breaks down, some failure and that's it.

polo54 wrote:

The cap was unscrewed on a cold engine, I know that it does not unscrew on a hot one,

If a colleague had marked it at the beginning, there would be less guesswork.

polo54 wrote:

in the manual from 206 with the same engine it says that when bleeding the system after replacing the fluid, the tank should be open, and here it is not possible just, half a minute and the liquid crashes, some failure and that's it.

I do not know exactly how it is presented in the manual, but if this happens with the engine running at idle, it may indeed be the beginning of a failure (blow-by), but if this happens with a sharp increase in RPM and holding them at a high level for a while , fluid may be ejected with the reservoir open. Something like this surprised me in a megance and I thought I had a blow to the cooling system, but it wasn't. The second surprise was when, instead of the original cork, I put on a cork with a hose and put this hose into the bottle (to the bottom). Then, with this sharp increase in revolutions, the liquid was ejected into the bottle, but as soon as I slowed down the revolutions, the liquid from the bottle was sucked back into the surge tank. I also noticed that the described trend was only present when, on a cold engine, the fluid level in the expansion tank was above halfway between the MAX and MIN marks.

We'll see what will happen, so far I gave my friend the car and told him to watch the coolant level in the tank, after some time I will let you know if everything is fine or not. Thanks to everyone for the answer. Regards

Hello everyone, but something is wrong.Yes, my friend made over 600km home and the whole road was ok, then he did 15 km and there was such pressure in the system that it spilled fluid on the connection of the lower hose going to the radiator and the radiator on this clamp , any ideas?

At 1.4 8V, the gasket likes to rot and also likes to leak through the oil supply channel.

Replacing the gasket as a piece of cake.

polo54 wrote:

any ideas?

Could be badly vented. There are 2 vents, one on the back of the head and the other at the entrance to the heater, deep against the bulkhead wall.

diodabg wrote:

Could be badly vented.

I do not know what it looks like a Peugeot, but in all the cars I have had and I have, if the thermostat was opened (a large circuit was opened), the system automatically vented completely.

polo54 wrote:

Yes, a friend made over 600km home and the whole way was ok, then he did 15 km and there was such a pressure in the system that it ejected fluid on the lower hose connecting to the radiator and the radiator on this clamp, any ideas?

Here, the thermostat was definitely open. Perhaps sometimes the thermostat may get jammed, but then there should be an information on the board about an excessive increase in engine temperature (if the engine is not gassed), so in my opinion, you need to check whether the control (indication) of the engine temperature is efficient, possibility of blocking the opening of the thermostat. In connection with the leakage described, it is also checked whether the plug on the expansion tank is functional, because it should not allow such a pressure increase.
I would also check if there is any blow to the cooling system.

gimak wrote:

I don't know what a Peugeot looks like

You can see buddy that you don't know what a Peugeot looks like
There is a reason that they made these vents because the air must be released if the small circulation hoses are directed downwards.

gimak wrote:

he should not allow such pressure to rise

The stopper is released at a pressure within 1-1.4 bar. Old, rotten snakes can't stand it.

diodabg wrote:

You can see buddy that you don't know what a Peugeot looks like

And BMW is at all.

diodabg wrote:

You can see buddy that you don't know what a Peugeot looks like
There is a reason that they made these vents because the air must be released if the small circulation hoses are directed downwards.

I wrote it unfortunately, because I know what the Peugeot looks like, but I do not know the spatial cooling system in this car and I also know very well what the vent plugs are for.

gimak wrote:

polo54 wrote:
Yes, a friend made over 600km home and the whole way was ok, then he did 15 km and there was such a pressure in the system that it ejected fluid on the lower hose connecting to the radiator and the radiator on this clamp, any ideas?

It follows from this text that at the beginning the system was vented, because I do not think that driving on the 600 km route, with the air in the system, was normal.
And even if the cooling system was not thoroughly deaerated at the beginning, while driving, when the thermostat opened (and it certainly did), the pump should chase all the bubbles to the expansion tank during the 600 km of travel. In addition, the inefficient cooling system is accompanied by an increase in the temperature of the coolant, which the author does not mention.

I did not mention the temperature, because it is surprisingly okay, i.e. it oscillates around 90 degrees (reading from the temperature indicator and in the computer), a friend called me today and it looks exactly like it is good when driving, but how to he will stop for a while or he will quench it, then he throws out the liquid, he told me so much.

polo54 wrote:

a friend called me today and it looks exactly like driving it is fine, but when he stops for a moment or quenches it then throws out the liquid, he told me so much.

Reading this last entry, this begs me:
And the radiator fan turns on at all, does it work?
While driving (even faster), it is cooled by the rush of air and the fan does not have to turn on. As the cooler is efficiently efficient, the momentum of the air while driving is enough to cool the engine. Slower driving or stopping, the fan must "work", maybe it does not turn on as it should and that's why such "circuses". The fan simply does not turn on as it should and during this time (slow driving, stopping, even turning off a well-warmed engine after driving), the engine "boils" and the fluid is ejected ...

Do you have air conditioning?

polo54 wrote:

I did not mention the temperature, because it is surprisingly okay, i.e. it oscillates around 90 degrees (reading from the temperature indicator and in the computer), a friend called me today and it looks exactly like it is good when driving, but how to he will stop for a while or he will quench it, then he throws out the liquid, he told me so much.

As he wrote wojtek1234321 .
My neighbor in a garage in a Ford Fiesta has a similar situation. It does not lose the fluid while driving, but when it comes to the garage and opens the garage door, the expansion tank starts to boil over. The fan turns on for him, I guess it's a bit late, but the neighbor prefers to add liquid instead of going and checking the temperature sensor