PSA electronic thermostat operation

[xantia_v6]

The thermostat is only partially electronically controlled. It still has a traditional wax element that opens the the thermostat when the water is hot. The electric control is only a heating element that gives extra heat to the wax capsule to cause extra cooling when the engine is working hard. So failure of the electronic control will not cause massive overheating, most of the time you would not even see any change in the temperature gauge.

[adhi89]

I filled up the reservoir with water. Did a small drive. Water was still there in reservoir and the pipe to the radiator was cold. After some time, the Thermostat did open and the water from Reservoir was sucked in by the engine. So may be the Thermostat is ok.

Turned off the egine. After few hours opened up the cap of tank to fill in some water again.

Now I have booked an appointment with Peugeot Händler for 24.2.
They say on phone that they will do pressure test to find leakage. I dont see any leaking water anywhere.
Lets see what they find out

[sar77]

There is a high probability that the engine cylinder head gasket is punctured. Check that there is no significant increase in pressure in the cooling system.

[adhi89]

There is a high probability that the engine cylinder head gasket is punctured. Check that there is no significant increase in pressure in the cooling system.

Yes. This can be a reason for sure. Hopefully not but.... it can be.
Any idea how to check Pressure in Cooling system? I mean pressure drop during Pressure Test will happen if there is some water leaking. How to check pressure increase?

[sar77]

Usually, an abnormal increase in pressure can be noticed after a longer or shorter drive by pressing the pipes of the cooling system - they are "very hard" or you can even visually see that they are swollen.
In cars of older models with a coolant filling plug on the radiator, after removing the plug, it was possible to see that the coolant was "boiling", i.e. it releases gas.
Another sign is a change in the color and smell of the exhaust gas, as some of the coolant enters the cylinders. You may not notice this in engines with DPF filters.
The engine head itself may be cracked.
If the gasket defect can be observed by careful visual inspection (obviously after removing the cylinder head), then the head defect can only be observed with special equipment in the repair shop during the hydraulic test.
Both happened to me with two different cars.
Coolant boils when a large amount of gas enters the cooling system, creating an air jam and stopping circulation. The resulting steam pushes some of the coolant out of the cooling system through the plug in the expansion tank.
It cannot be ruled out that the problem is with the coolant pump.

[adhi89]

Usually, an abnormal increase in pressure can be noticed after a longer or shorter drive by pressing the pipes of the cooling system - they are "very hard" or you can even visually see that they are swollen.
In cars of older models with a coolant filling plug on the radiator, after removing the plug, it was possible to see that the coolant was "boiling", i.e. it releases gas.
Another sign is a change in the color and smell of the exhaust gas, as some of the coolant enters the cylinders. You may not notice this in engines with DPF filters.
The engine head itself may be cracked.
If the gasket defect can be observed by careful visual inspection (obviously after removing the cylinder head), then the head defect can only be observed with special equipment in the repair shop during the hydraulic test.
Both happened to me with two different cars.
Coolant boils when a large amount of gas enters the cooling system, creating an air jam and stopping circulation. The resulting steam pushes some of the coolant out of the cooling system through the plug in the expansion tank.
It cannot be ruled out that the problem is with the coolant pump.

So i had the appointment today and as per Peugeot Workshop it is ditto whats mentioned here. Great analysis @sar77
Head gasket damage causing gases entering coolant system. Leading to pressure in the cooling system and pushing coolant out of expension Tank cap.

Peugeot workshop was kind not to charge me anything for the diagnosis and but gave me an estimate of 2250€ for the repair.

The repair include not only Head Gasket replacement but also the Timing Belt. Because they say its only a small extra effort to do it once we are doing Gasket. Timing Belt kit costs 200€ so i think also that it makes sense.

The issue is only that Peugeot workshop has hourly rate of approx 120€. So more than half of 2250€ is labour cost. Even the mechanic said, you will get this job done cheaper if you do it from other than Peugeot.

Now i am thinking what should be done. I have the car since 3000km and 6months only. And spending 2250€ is a bit too much to digest.

[sar77]

Unfortunately, the prices in branded services are extremely high. Ask if they are talking about a new cylinder head? It is possible that the head is deformed due to overheating, but usually it is enough to just grind it, which will certainly cost much less than a new head.
If the car has traveled less than 100,000 km, I think it is not appropriate to replace the entire timing belt set (perhaps only the belt itself). All the more so, as you mentioned that you rarely use the machine.

[adhi89]

Unfortunately, the prices in branded services are extremely high. Ask if they are talking about a new cylinder head? It is possible that the head is deformed due to overheating, but usually it is enough to just grind it, which will certainly cost much less than a new head.
If the car has traveled less than 100,000 km, I think it is not appropriate to replace the entire timing belt set (perhaps only the belt itself). All the more so, as you mentioned that you rarely use the machine.

Thanks for the reply.

No, unfortunately the car has done 150T km and the last Belt change was around 100T km. So may be spending 400€ on the belt is fine. Because separately that job is again 1200-1300€ including labour cost.

Well the Head itself is not included in the price. The estimate is in German, but i can try to mention whats mainly in it.
- 7hr labour for Head gasket @ 107€/hr
- 1.5h additional for Belt change @ 107€/hr
- Belt Kit for 175€
- Head Gasket 95€
- Head Bolts 25€
- Engine Oil and Filter 100€
- Coolant 25€
- alot of different seals and small stuff
- 20% Tax on all of it.
Sum 2250€.

Asked another across the road workshop. Showed him the Peugeot estimate, they gave estimate of 1600€ for the same job. But i am a bit uncertain about them.

I like the car alot otherwise, so i want it to be in best condition soon again. Just trying to find a place where its good taken care of.

[adhi89]

Hello all
Just wanted to provide some feedback.
So got the work done by a workshop. Provided him with Parts through Autodoc (wanted to select the best aftermarket stuff possible). Sum is around 1600€ including New timing Belt, head Gasket, Oil with Filter, Coolant, and Seals. All stuff what Peugeot recommended in their estimate. Plus new NGK Spark Plugs, Airfiilter and WaterPump.

The Head gasket was not punctured but the black rings (seals) around Piston holes was worn off at multiple locations. I think the water entered from there. The head had slight deformation as per Mechanic and is grinded on special tool.
Now i really hope all is well and i can test it somehow soon enough.
Some pics attached.

[Brankobass]

Hello everyone, a few days ago I was at the local service center because the air conditioner in the car was not working properly, it was only blowing warm air... The service center said that it was not a problem with the air conditioning system, but a problem with the coolant thermostat, because it gave them the error P26A5-00 and that is why it was blowing warm air into the cabin. It is DS5 08.2016 2.0 180hp. From the previous posts I can assume that they were right. Is this possible, will the air conditioner work properly again if the thermostat is replaced?
Sorry, the service report is in German.

[xantia_v6]

It is likely that the A/C will work again when the thermostat is replaced.

[rkomzz]

The thermostat is only partially electronically controlled. It still has a traditional wax element that opens the the thermostat when the water is hot. The electric control is only a heating element that gives extra heat to the wax capsule to cause extra cooling when the engine is working hard. So failure of the electronic control will not cause massive overheating, most of the time you would not even see any change in the temperature gauge.

Hello everyone,

I’ve been having a strange problem with my car Citroen DS5 2.0 hybrid, and think it has something with thermostat. The engine temperature stays steady at 90°C during driving every time no fluctuation , which seems normal, but after I turn off the engine, if it’s been well warmed up the temperature starts to rise. If I start the car again it get back to normal almost instantly.

What’s also weird is that the area around the engine feels noticeably warm when I open the hood, even though the temperature gauge still shows 90°C. Sometimes, the radiator fan also turns on in these cases, which I assume is normal, but still, something doesn’t feel right.

I’ve also noticed that after the engine is properly warmed (driving a while with 90°C), the fuel temperature reading on my cheap ELM327 adapter starts rising as well.

So, I'm assuming that this is the kind of overheating issue that was quoted. The problem only seems to happen when the engine is properly warmed up. The mechanics I’ve gone to brush it off, saying everything is fine, but I know something’s not right.

I suspect thermostat, Has anyone experienced something similar, or have any ideas on what could be causing this?


Thanks

[Mihael_M]

This is normal behavior, when the engine is turned off there is no antifreeze circulation and the temperature may rise briefly but will then definitely drop. The radiator fan would also turn on if the temperature was too high.

[rkomzz]

This is normal behavior, when the engine is turned off there is no antifreeze circulation and the temperature may rise briefly but will then definitely drop. The radiator fan would also turn on if the temperature was too high.

Hello Mihael,

I don't think it's normal because the fuel temperature is also rising above 70°C while driving, which wasn't the case before. This suggests that some parts might be heating up more than they should.

What I noticed at that time on the FAP app is that the AirManifold temperature is also increasing, which makes me think that something is off.

Would it help if I replaced the entire thermostat housing with the sensors? I change the coolant every two years, could the radiator maybe still be clogged?

[PaulC5]

Link to your topic on the same subject so people can post in one place viewtopic.php?t=87353