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Discussion Starter · #1 · (Edited)
I just did some spirited morning driving on the twisties. After about 15 minutes power was cut and the car had water temps on max.

I pulled over and am let her cool down. It is no longer on max and orange but I am surprised this happened after such a short time driving her.

She made it home ok but it appears there might be a sensor issue as there wasn't any fluid where she slept last night. Water levels were on the high side besides not pushing her hard.

Any advice is appreciated.

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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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Discussion Starter · #3 · (Edited)
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
Thank you Mike for being so helpful.

No fishy smell.

I am going to try snd get someone to fly out and replace them. How you advise how long to replace them on a Spider pls?

Thanks again
 

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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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Discussion Starter · #7 ·
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
I am tried getting a good McLaren tech to fly out here to install new sensors but it is proving tough due to current workloads.

I am going to try the same from McLaren Barcelona.

When you say not to drive it is that because I risk doing damage to the car or is it because if the sensor fully fails the car will be stuck somewhere and won't run?

I was loving the driving here.... The highlight of my trip... so gutted.

Is it worth checking the coolant level? Is it easy to do? I tried finding info on how but couldn't find much on how to do it for thr 675.
 

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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.
PLUS, I would replace the Intake Manifold seals since it has to come off to access the T-stats... Depending on AGE (not so much mileage) I would be also thinking about at least the upper rad hoses...It is all coming apart and it would suck to have to pay someone again to go back in there... I cannot tell you how many times in my paid career in automotive repair, that I have had to "re-do" work that was done due to a co-located component failing... I just did ALL of the above and more due to age of the car (2015) vs mileage. Ozone slowly ruins rubber components! Best of luck to you!
 

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Discussion Starter · #10 ·
PLUS, I would replace the Intake Manifold seals since it has to come off to access the T-stats... Depending on AGE (not so much mileage) I would be also thinking about at least the upper rad hoses...It is all coming apart and it would suck to have to pay someone again to go back in there... I cannot tell you how many times in my paid career in automotive repair, that I have had to "re-do" work that was done due to a co-located component failing... I just did ALL of the above and more due to age of the car (2015) vs mileage. Ozone slowly ruins rubber components! Best of luck to you!
I fully agree with you!

I just checked the coolant level and it seems ok.

My first tiem opening the engine lid and checking her out. So nice in there.
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I am tried getting a good McLaren tech to fly out here to install new sensors but it is proving tough due to current workloads.

I am going to try the same from McLaren Barcelona.

When you say not to drive it is that because I risk doing damage to the car or is it because if the sensor fully fails the car will be stuck somewhere and won't run?

I was loving the driving here.... The highlight of my trip... so gutted.

Is it worth checking the coolant level? Is it easy to do? I tried finding info on how but couldn't find much on how to do it for thr 675.
Sensors? He's telling you that one of the thermostats is stuck closed, which means there isn't enough coolant circulating. If you drive it like this, it's one of the quickest ways to destroy the engine.
 

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Discussion Starter · #12 ·
Sensors? He's telling you that one of the thermostats is stuck closed, which means there isn't enough coolant circulating. If you drive it like this, it's one of the quickest ways to destroy the engine.
Oh boy... Wow

Glad I asked. I assumed it was a thermostat sensor that was malfunctioning not that it was affecting the coolant circulation.
 

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Oh boy... Wow

Glad I asked. I assumed it was a thermostat sensor that was malfunctioning not that it was affecting the coolant circulation.
That might be possible, but he's a factory trained expert, and he's saying the thermostat is not opening. Better safe than sorry. Even running the engine hotter than it should be for an extended period is risky. If it actually fully overheats, you can cause catastrophic damage within minutes.
 

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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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Discussion Starter · #15 ·
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.
Got it. Thanks!

Would you replace the intake Manifold seals at the same time or anything else, considering I am likely flying someone in?
 

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Got it. Thanks!

Would you replace the intake Manifold seals at the same time or anything else, considering I am likely flying someone in?
Manifold seals should be changed any time they come off, they're cheap (well, usually, lol). Same goes for any kind of cheap seal or wear part that has to come off anyway.
 

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Got it. Thanks!

Would you replace the intake Manifold seals at the same time or anything else, considering I am likely flying someone in?
Manifold seals should be changed any time they come off, they're cheap (well, usually, lol). Same goes for any kind of cheap seal or wear part that has to come off anyway.
The Intake Seal Set was 194.27 USD, one month ago when I did this job.... Pennies compared to the cost of the T-stats!!
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