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Discussion Starter #1
Hi,

I've been a long-time lurker, reading a number of articles here and other places like Honest John's to try to find the solution to my issues with this 307 - the overheating in particular. In Australia, where we often have seven to ten days in a row with the weather over 40 deg C, we need to have a car that does not give us the STOP warning every time we drive it for longer than 20 minutes...

I fully expect a number of questions from you all as I have been chasing this around for such a long time that I'm bound to miss something until asked.

Thanks to other posts here and plenty of Googling, I have finally succeeded in clearing up one question we've had - the car is definitely a 2.0lt diesel Estate. Googling has led me to be able to decipher the VIN and this forum has led me to create a Service Box account that has given many details. The engine type appears to be TURBO DIESEL DW10TD.

In my extensive Googling, I understand that there may be two, or even three sensors that I need to possible fix or replace - but I digress, I should give the symptoms and the currently "attempted" "repairs". Both sets of inverted commas definitely clang into place there...

Symptoms:
At almost any time of year that the outside temp gets above 25 deg C, the car temp gauge will creep up to over 110 deg, and will often red line, causing a STOP warning. When the car is stopped, the engine fan will keep running for some time after the car is switched off. I've never timed it, but I'd guess up to five minutes, maybe a little more.
While driving coasting for a while can drop the temp gauge [slightly], running the heater on can drop the temp gauge slightly and simply driving with windows down but all A/C off will keep temo gauge down on moderately warm days. Nothing keeps the gauge down on a hot day.

'Repairs' and checks:
First, NONE of these mechanical type repairs have been performed by me. I have done minor checks and actions like coolant top-ups, but that's about it.
In no specific order:
Coolant overflow is kept at all times between MIN and MAX and almost never needs topping up.
There is NO oil or scum in the overflow.
Oil level is checked fairly often (bi-monthly) and is at roughly 60% between MIN and MAX on the dipstick.
Water pump has been replaced THREE times.
Coolant system has been leak checked.
Coolant system has been pressure tested.
Coolant system has been flow tested.
Overflow always has good pressure if I check it manually myself.
One summer day last year, when the car redlined for temperature reading, I took it to a local mechanic who hit the radiator and the water pipe leading to the engine with his infrared themometre and both readings were between 100 and 110 deg C.

Sensors:
In my reading, I understand that there are at least two, maybe three, sensors I need to check before I go for the major mechanical hits. First is the engine temp sensor to the right of the engine with a green plug. Second is the coolant level sensor on the bottom of the overflow globe. Third is the ECU?

What I need (and some additional info that might sway your recommendations):
I'd like to try to change both the temp sensor and, maybe, the coolant level sensor but have no idea which is the correct part to buy on eBay (or wherever).
The additional info is this.
Firstly, on a semi-frequent basis, we get an Engine oil level indicator alert (page 34 of the in car manual). We don't always get the too full alert and nor do we always get the oil low alert - it seems to be random (hence the regular checking of the oil levels). The oil is always a good level.
Secondly, only a couple of weeks ago, as I was frustratedly poking around under the bonnet, I discovered that the coolant level sensor lead is unplugged! After an 'ah-hah' moment, I plugged it back in, only to discover that now when I start the car, I get a new STOP light (that doesn't stop flashing) with a new warning light for the coolant. As soon as I unplug the lead, the warning light stops occurring at startup. Who knows how long this has been the case - I suspect it was dodgy bloke up on the Central Coast over four years ago, but can't be sure...

What can people recommend? Should I change the temp sensor and which one do I buy? Should I change and/or clean the coolant level sensor? With these two fault lights at start up, is it possibly the ECU/ECD other TLA beginning with 'E'? From what I have read, a real Peugeot mechanic needs to change the ECU because it needs to be initiated or something...

Thanks in advance,

CB

Some photos follow if they help...

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HI...have you checked the air flow through the radiator...that can cause problems?
 

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Put the heater on full with blower on full if temp starts to drop you have a blocked or clogged radiator or as above airflow to radiator could be an issue such as if a/c fitted condenser matrix clogged with debris

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Discussion Starter #4
Thanks for the quick reply Noddy. How would I check the airflow through the radiator? Do you mean literal front-to-back airflow while driving? In otherwords, blocked fins?
 

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Put the heater on full with blower on full if temp starts to drop you have a blocked or clogged radiator or as above airflow to radiator could be an issue such as if a/c fitted condenser matrix clogged with debris
Thanks Windy, the heater on full will drop the temp slightly (less than one step on the gauge) and usually only when the temp outside is less than 28 deg C.

We've had the radiator flow tested, but not airflow tested if I understand wht Noddy means correctly.

Turning on the heater will never drop the temp on the gauge to anything close to normal operating temp.
 

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Hi...I've come across rads that look ok insitu but if the core is blocked/corroded its not letting air though...can be caused by age...or environment..ie dusty...worth taking off and checking the core to see if you can see clearly though it..
 

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Rad flow can be misleading. I personally would start with a new radiator, off the shelf not off another car! That way you will know both internal and external flows are 100%. Then I would carefully inspect all hoses. They can collapse and restrict flow. Had one recently on a Vauxhall Astra.
 

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You don't mention if the thermostat has been changed as it could have part failed and is not fully opening restricting flow through rad

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Sensors wont make any difference if it REALLY is getting hot it can only be lack of cooling by the rad due to being clogged or not enough airflow or the thermostat no opening fully it wont be the head gasket at least not yet but if you keep getting it hot it will eventually fail.

These engines rarely overheat.
 

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If the water pump is at 110 degrees the radiator isn't doing its job. As has been mentioned it's either the radiator is internally restricted - a flow test won't tell you anything useful, or air isn't flowing through the radiator, either because the radiator fins are blocked, the a/c condensor is blocked, or both. I presume Peugeots are sold new in Australia?, if so they should be designed to cope with Australian summers. It's fair to say you are having record breaking heat in many parts, where are you?.

Roger.
 

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Use an infrared thermometer to measure the temp on top and bottom hose and also right across the face of the radiator core top, middle and bottom. The core must read even temp across the face in each level. There should also be a temp difference between top and bottom hoses. If the radiator face is hot in some areas and cooler in other areas on the same level then rad core is blocked. If hoses are same temp then rad is not working.
Thermostat is another suspect. They are really a consumable, I would change it as a matter of course..
Air flow through radiators is also critical, make sure fins are clear. Often debris can accumulate between the radiators so check carefully.
Good luck.
 
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