How hot is too hot!

[noonoo46]

hi guys, let me start by saying im an rac patrolman. I understand engines and cars very well but i have a question i hope you can help me with. ive been restoring a griffith 500 and am delighted to have it in a position were i can now drive it. my one query is should it really run that hot??
If i start it up and let it idle, it heats up nicely. the thermostat opens and the coolant circulates through the rad nicely. the temp rises to a little bit below the red (which on my gauge starts at 110c), the fans cut in and the temp drops a bit till the fans stop and the process starts again.
On the open roads at desent speeds the temp sits a bit over 90c but in traffic it creeps up to almost the start of the red again. Let me stress now that it has never entered the red.
what i need from you guys is in your experience, is it normal for a griff 500 to run so close to the red on idle and in traffic as im used to temp gauges sitting nicely in the middle of the gauge and not going near the red.
Any opinions/advise gratefully recieved

[chris52]

Mine never gets near the red. With the colder air temps at the moment its rare it will go much above 85, on a hot summers day in traffic it has a couple of times read over 95 but never anywhere near the red.

Chris

[Del 203]

Have you measured the temp or trusting the gauge ?

[noonoo46]

ive been trusting the gauge up till now however, im borrowing my mates laser temp reader tomorrow so i will measure it over a few places on the cooling system and engine

[Del 203]

noonoo46 said:

ive been trusting the gauge up till now however, im borrowing my mates laser temp reader tomorrow so i will measure it over a few places on the cooling system and engine

Are they not in the company vehicle ?


I don't like over 90 ....

[noonoo46]

unfortunately not. the rac supply alot but not everything im affraid

[noonoo46]

yeah. they all say im mad but all want a go in it!!!

[grumbledoak]

The cooling system should be having a decent attempt at keeping her to 90°C. A bit of variety over the years, and probably more between each individual car, but for a late model car the two fans should come on seperately somewhere about 92°C and 96°C. You should not be seeing 100°C+, and I'd pull her over at 110°C.

That said, I wouldn't trust the guage much. If she cycles through getting hot, one fan, two fans, then both fans off, chances are it is all working and the guage isn't accurate.

IR 'jobby' should help you confirm.

[noonoo46]

i havent let them drive it, just took them out in it. i think 2 of them need new pants now!!

[Bluebottle]

If the otter switch is cutting the fans in and out on tickover then the fans are pulling the temp down below 90Deg.C. If your gauge is saying anything above that when the fans switch off, your gauge needs a inline callibration resister to match the sender unit.

E.T.A.
Which temp sender have you got it wired up to as there are two? one is the old LR unit beind the dizzie and the other TVR one at the front.

Edited by Bluebottle on Saturday 27th March 10:31

[deeen]

I'm sure you know, but do you have coolant in it? cools better than plain water. Also there are 2 thermostats listed, I always used the cooler one.

[steve-V8s]

You have probably figured this out already but the gauge and the fan control is done by different sensors. Either of which have a reputation for being that accurate. The optimum engine temperature for performance is reckoned to be around 82c but they do typically run at around 90.

[Pasco]

steve-V8s said:

You have probably figured this out already but the gauge and the fan control is done by different sensors. Either of which have a reputation for being that accurate. The optimum engine temperature for performance is reckoned to be around 82c but they do typically run at around 90.

Make sure you have the lower temp otta switch and remove the pre cats to reduce under bonnet temp ASAP that's my advice

And welcome to the Mad House

HTH

[noonoo46]

I replaced the coolant today as it was quite weak. Checked the actual temp of engine and cooling system in several places and it didn't go over 96c. The gauge was Reading the same too. Just goes to show the importance of fresh coolant in the right quantities. Thanks for your help guys

[Hamburglar]

My gauge spends the majority of it's time between 85-90, but it will intermittently do crazy things like reading 20 degrees lower or sometimes not at all! If the fans are cutting in at idle you should be fine.

[BliarOut]

Check the splitter is there, it really helps the car drag the temp down if she's had a bit of a heat soak.

[crackedfinger]

There is another way of running slightly cooler - I'm running a lower stat (off memory it's a 72) and otter switch, cuts in a few degrees cooler. Never see over 90 now. Got the 2 parts from from Leven.

[jacjac]

I am paranoid about running too hot. I don't like to run much above 90 degrees.
I have the Modwise 2 stage fan control unit that works well and is fully adjustable. I also have a manual button fitted under the dash which over rides any other fan control. Useful if we've been going hard and can see I'm coming to a stop for lights or traffic - I can preempt the temp rising and get the fans going. It nice to be in control!

[lockhart flawse]

If you fit a slightly smaller front number plate (between MOTs) you will find that the running temperature stays a lot lower. It doesn't stop the temperature rising when you are in traffic but it will take a bit longer to get to the 90 degree level at which point the fans cut in. Personally I don't like the noise that the fans make and so anything which reduces the time they are on is a bonus for me.

L.F.

[noonoo46]

Thanks for your help guys. Thunk I've sorted it. Used a bottle of water wetter an fitted a panic switch to turn the fans on in traffic. Drove it 100 miles on Thursday an the temp didn't go above 90 when moving and didn't go above 100 when in traffic.

Edited by noonoo46 on Monday 5th April 16:27