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McLaren 12c 2012
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Hey, no problem I can help here, dont panic. If you have checked the coolant levels are fine and you have no leaks. You 100% have a thermostat issue. This unfortunately is common on the 675LT for some reason.

It will probably be one that has failed but to be honest I would replace both for good measure. Problem will be solved following this. Let me know how you get on.

This will be your issue so please dont waste money looking elsewhere or have some dip shit dealer tell you different.

I was working on a 650s recently with the same issue, its now fixed. FYI with normal and spirited driving, you should never experience water temps passing half way, if all is well they will never go above middle on the gauge they can creep slightly on track but not much at all. I myself have had a couple of split pipes on my 12c and as soon as I noticed the water temp creep up I pulled over straight away before getting into the danger zone. If you have a leak while the engine is hot and you are driving, you can smell it straight away. Hot coolant tends to smell fishy through the vents.

Mike
 

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McLaren 12c 2012
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This thread is an example of why this forum/community is amazing.
Well yes now there are some knowledgeable people on it.. Ahem :):) I have to say when I first joined a couple of years ago, in terms of info and help, this forum was pretty useless.

You should be able to have a half decent mechanic in Spain fix it depending on where you are. For the parts you can obvs try the dealer in Barcelona.. its not a hard job but it isnt the easiest, I would say around 5-6 hours. The thermostats are at the front of the engine near where the cabin is, the coolant will need to be done as well, might as well while he is there.

Dont drive the car until its sorted. There is a new part for these now so this shouldnt happen again once its been sorted. Very nice car by the way. Im coming over to Spain in a few weeks...

Buon dia
 

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McLaren 12c 2012
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Ok good to see the coolant level is good. Basically what will happen is that the thermostat is basically a door in simple terms, this door opens and allows hot coolant out of the engine block to reach the radiators, cool it, and then put it back into the block again. This is how the cooling system works to maintain the engine coolant temperature under 100c.

If the hot water cannot be cooled and get through the door, it cannot disperse its heat and the engine will overheat and blow the headgasket, or something much worse. running the engine over temperature for a period of time can warp the cylinder head, trust me you dont want any of that.

FYI there is no coolant thermostat sensor. The thermostats on mclarens are electronic yes, but it is a heating element that aids in warming the coolant from cold start to get the coolant up to temp faster and also works when hot to keep optimal coolant temperature.

Since the temperature went down, there is a chance that one of the stats didnt open and got stuck, I would drive it normally, somewhere you know you can stop and see if it does it again, either way, you can really push a mclaren hard on track and not see a temperature over 105c as the coolant system runs on high pressure and is moving through the radiators quickly, so it should never get that high, so something is probably wrong and considering the 675s are known to have stat issues, I would get it looked into and have them replaced to the newer versions.

Any further help you need just post.

Mike
 

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McLaren 12c 2012
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Welcome mate, see, these cars are really fine to own if you have help, if not you are at the mercy of the dealer, and that REALLY sucks. Most of the time they create more problems as well.
 

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correct,thermostats have a sensor built in.
they do not. Those are heater elements. They are used to bringup temp faster. They are not reaponsible for water temp readings.

there are 3 sensors responsible. One on each main water pipe, and one in the cylinder head for head temp.

Can you post your exact symptoms and error codes pls thanks

note that if the water pump seal has failed, you will get gearbox and clutch overheat messages and all kinds of things pop up related to temperature
 

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Very good, would be surprised if your engine coolant sensor has actually failed though. Rare, will also not cause shifting issues, if it does, its something else causing it.
 

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McLaren 12c 2012
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let the mcmedics sort it our for your sanity. @EMF Audio (McMedics) @ima2nr (McMedics)

Have faith, once its fixed it will be fine, it isnt the car thats the issue. Its the shit mechanics. Period.

the dealers have zero problem and diagnosing skill. Just throw parts at it and dont thibk about WHY those errors are occurring which another factor is indirectly causing it
Its a 675 right? Then chances are the stats have failed in that case or the water pump has issues.
 

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Hey, new member and sorry to hijack the post but I had a similar issue taking my 675 on track 2 weeks ago .... albeit at Yas Marina in Abu Dhabi at 40C temps. But my oil temp was getting hot as well as coolant. They were getting into the orange after only 1-2 fast laps and then I was slowing down straight away so as to not risk anything. The temps went back to normal really quickly but meant that I couldn't really push the car or get many consecutive laps in. My car is however still under warranty so I mentioned it to them when I took it in for post-track inspection and they've just come back to say "our tech team did not find or duplicate the overheating issue so as a precaution we sent a technical support to the factory" - no idea what the latter part of that means but seems as though they think nothing is wrong.

So it seems pretty apparent that I need to push them to replace the thermostats, but would this help with the oil temps as well?

I also read in another thread that temp issues are only apparent when the AC is running ..... but when it's 40C and 100%humidity I don't really want to have to choose between AC and high engine temps lol
On a 675LT it will be your stats. I am in Dubai and can help you if needed or any advice.
 

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Yes as stated above this is normal, I would burp your car leave the engine running from cold until it heats up, check for trapped air, will come up bubbling
 

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McLaren 12c 2012
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mate dont just sell it cos you had a small issue. ull regret it, any issues I can tell you what the problem is and you can tell them to just change that to avoid them keeping the car for weeks.
 

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Tell me what issues you have mate and I will tell you how to fix them and you will very unlikely have an issue again. I dont mean to sound like a dick, but you are lucky I am in Dubai. I know these cars like the back of my hand.

What you will find here is that the "mechanics" actually create the issues. Just trust me on this, my car went to habtoor once it was a total disaster. Even though they are not the dealer anymore, they are all the same. Any issues I have with my car I fix them all myself and the fixes work? You know why...? Because they have been done properly and by the book.

You in the McLaren owners Whatsapp group in Dubai?

Ull Love this car again. Trust me on that.

Ex Formula racing mechanic
Ex McLaren
Engine ECU calibrator.
 
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