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overheating


simonhar

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car is standard 1.6 k SV, selfbuild 5 years ago. Cooling system works, thermostat 74c seems to opn, temp goes down- fan comes on at correct temperature but usually stays on with little reduction in temp. If I am in a traffic jam over a period of 15 mins or so the temp hits 100 and sometimes higher. Get moving again and temp drops to a constant 80. So the car never overheats on trackdays or when moving.

This would suggest to me that the air flow through or the efficency of the radiator is not sufficent in traffic and therefore needs a bigger better rad. Caterham claim that the standard system is sufficent in any situation and there must be a fault, but given what seems like a normal working pattern of all the components except when ging slowly I don't see where there could be a fault. There is no air in the system! Should I get a bigger rad?

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Sounds like the fan if a dicky sender can be ruled out.

 

Has it always done this 🤔

Is it possible that the fan is moving the air in the wrong direction .. i.e. it was assembled incorrectly *confused*

 

Keep off the straight and narrow *tongue* 😬

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Mine does exactly the same. I'm still unsure what if any thermostat mine has, being an ex racer? I control the fan manually from the dash switch, but noticed when in traffic at the weekend it would still reach 100 with the fan on, sometimes higher, until moving slowly when it drops to 80. *confused*

 

It could be the system needs bleeding for air, I'm going to see if I can fit a slightly more powerful fan, whilst still using the existing relay and switch?

 

New owner of BOSS

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It seems to do it more frequently in the last couple of years- I replaced the fan last year with a slightly higher spec(same dia) and its pulling air through the rad.Some of the hoses were replaced this year with a 74 stat being put in. I presume the mesh stonegard doesn't effect air flow by much? the sender seems to give temp readings that agree with the stat opening anfd the fan coming on.
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I second the problem with the fan - my 1.6 sat on the drive ticking over for over an hour last week while I tied on all sorts of stuff for the local gala here and here after jump starting it from leaving it two weeks on the garden.

 

Got to 80 - fan came on - it stayed at 80 degrees.

 

Bri

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I've had similar problems recently - fine on the road, pants at controlling temp when stationary.

 

Check the voltage that the rad is seeing when turned on and compare it to the voltage across the battery under the same conditions.

 

I was losing over a volt somewhere down the line and subsequently rewired this resulting in a much lower voltage drop. The fan speed and efficiency are really voltage-sensitive - so if you're not getting the jolts down at the far end, your fan won't be doing much of note...

 

          🙆🏻 🙆🏻 🙆🏻 🙆🏻 🙆🏻

Alcester Racing

7s Equipe™

🙆🏻 🙆🏻 🙆🏻 🙆🏻 🙆🏻

 

Alcester-Racing-Sevens.com


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Checked the voltage -thats fine. I just get the impression that the fan does not pull enough air through. I presume a more efficent radiator would compensate for this but there seems to be a body of thought that the standard set up should be fine. Can radiators get less efficent as they get older? Is this an early sign of HGF failure(no steam or obvious coolant oil mixtures) I note that the new models have a cowling to increase the area'swept' by the fan
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If youve ruled out any problem of integrity/pressurizing I would suggest continue looking at getting air through the rad when stationary (ie the fan) rather than a bigger rad. I think that the efficiency of a bigger rad will just cause problems of being too cool when cruising, yet will still suffer when stationary.

 

 

 

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