Temperature Gage reading 110+
Discussion
so i was driving for a good 30mins today checked out a few diff alloy refurb places, noticed the temperature gage was rather high, it continued to rise into the red zone like 120+ i switched the fan on but it didnt effect it one bit tbf.
made it back home fine lifted bonnet and saw the coolant area (in see through tank) was bubbling like mad, clearly overheated. Checked it hour or so later and there's none in there now.. Swirl tank still fairly full with a greenish coolant in there, popped to local halfords they don't do such colour coolant just had blue.
Has anyone else had this issue? or could shed some light on what may be the cause I don't even think I can drive it now without correct coolant in.
Thanks
Steve
made it back home fine lifted bonnet and saw the coolant area (in see through tank) was bubbling like mad, clearly overheated. Checked it hour or so later and there's none in there now.. Swirl tank still fairly full with a greenish coolant in there, popped to local halfords they don't do such colour coolant just had blue.
Has anyone else had this issue? or could shed some light on what may be the cause I don't even think I can drive it now without correct coolant in.
Thanks
Steve
Edited by greyhulk on Saturday 8th August 14:21
mk1fan said:
Although does sound like something needs looking at. Thermostat failed? Good flush through if the whole system.
Will put abit of water in for now thanks, struggling to find same coolant that was used.. A lime green colour? Possibly the thermostat as u said tbh will get it to garage asapThe yellowy-green antifreeze is a glycol based coolant, a good quality one.
I have used that on piston engined aircraft cooling systems, and also on train engines, but I'm struggling to remember the manufacturer's name....
You say that you switched your fan on, but it made no difference? Is the fan actually spinning? It should come on automatically when the otter switch operates. But it's a good option to have a manual override switch.
If the fan is working as it should, then your thermostat may be failing to open or you have a dodgy pressure cap or split or leak somewhere in the cooling system so it is not holding pressure when hot. This means the coolant will boil over.
I have used that on piston engined aircraft cooling systems, and also on train engines, but I'm struggling to remember the manufacturer's name....
You say that you switched your fan on, but it made no difference? Is the fan actually spinning? It should come on automatically when the otter switch operates. But it's a good option to have a manual override switch.
If the fan is working as it should, then your thermostat may be failing to open or you have a dodgy pressure cap or split or leak somewhere in the cooling system so it is not holding pressure when hot. This means the coolant will boil over.
Edited by glenrobbo on Saturday 8th August 19:11
ok so im useless with engine stuff.. (pulling my hair out.. well beard)
struggling to locate the bloody thermostat! i have a feeling its the other end of the bottom rad pipe not top.
also just ran engine for a good 20mins, (added abit of distilled water to coolant to top it up) and i noticed my fan didnt kick in automatically when the engine temp hit about 90.. obviously switched it on manually and it stopped it rising and actually bought it down but im thinking would a faulty thermostat may stop the fan auto kicking in or?
I was reading the alternate parts list & its saying the 'QH QTH117K' thermostat (88 degrees), but that was stating it was for the S3.. i have the S1 2.8 V6 not sure if it would fit/work in my model of car?
also glenrobbo think this may be the coolant you was talking about? (it contains glycol like you mentioned too)
http://www.racetechdirect.co.uk/ca103-tvr-car-part...

struggling to locate the bloody thermostat! i have a feeling its the other end of the bottom rad pipe not top.
also just ran engine for a good 20mins, (added abit of distilled water to coolant to top it up) and i noticed my fan didnt kick in automatically when the engine temp hit about 90.. obviously switched it on manually and it stopped it rising and actually bought it down but im thinking would a faulty thermostat may stop the fan auto kicking in or?
I was reading the alternate parts list & its saying the 'QH QTH117K' thermostat (88 degrees), but that was stating it was for the S3.. i have the S1 2.8 V6 not sure if it would fit/work in my model of car?
also glenrobbo think this may be the coolant you was talking about? (it contains glycol like you mentioned too)
http://www.racetechdirect.co.uk/ca103-tvr-car-part...
Edited by greyhulk on Sunday 9th August 19:06
The fan is controlled by the otter switch in the top radiator hose, presumably you connected across that to get the fan working? It isnt connected to the thermostat in any way. If you connected so the fan worked, and that cooled things down, then presumably the thermostat is working OK.
Faulty otter switches are reasonably common. Mine will definitely overheat if the fan isnt working but stays just right in pretty well any conditions if the fan is working.
I would go for a new otter switch before even touching the thermostat housing.
However I would start soaking the thermostat housing bolts in WD40 just in case it has to come off later, those mounting bolts can be a pain to get out and you do NOT want to damage the thermostat housing.
Now that you have had it boiling you will probably have loosened lots of c--p in the water system. Take the opportunity to flush it out, use a hose and flush it the wrong way round as it were, until the water runs clear. Dont forget to flush the heater system as well. You might be surprised at the atate of the water that comes out!
If this cooling system is clean and working properly is is quite able to cope with this engine, even worked hard.
Faulty otter switches are reasonably common. Mine will definitely overheat if the fan isnt working but stays just right in pretty well any conditions if the fan is working.
I would go for a new otter switch before even touching the thermostat housing.
However I would start soaking the thermostat housing bolts in WD40 just in case it has to come off later, those mounting bolts can be a pain to get out and you do NOT want to damage the thermostat housing.
Now that you have had it boiling you will probably have loosened lots of c--p in the water system. Take the opportunity to flush it out, use a hose and flush it the wrong way round as it were, until the water runs clear. Dont forget to flush the heater system as well. You might be surprised at the atate of the water that comes out!
If this cooling system is clean and working properly is is quite able to cope with this engine, even worked hard.
greyhulk said:
im thinking would a faulty thermostat may stop the fan auto kicking in or?
A faulty "Otter" switch (circled) will stop the fan kicking in when needed. If all was ok when you used the manual over ride switch that would suggest (to me anyway) that there is nothing wrong with the thermostat. Have you seen this post?Re your anti freeze, once issue is solved I'd suggest drain and refill with known brand that you can then use for top ups if required

Edited by phillpot on Sunday 9th August 20:34
In your first pic, it looked like there were no wires connected to your otter switch. Maybe you could check this.
Whatever, they are cheap to buy, I just bought a new one on ebay for about 8 pounds. See link to other post for details of part number, etc.
In the "Useful Links" there are some alternative parts listings, which are also quite useful.
Whatever, they are cheap to buy, I just bought a new one on ebay for about 8 pounds. See link to other post for details of part number, etc.
In the "Useful Links" there are some alternative parts listings, which are also quite useful.
Thanks for the advice guys, will flush it out for good measure. Ive just had a look at the otterswitch it is wired in but one of the spades was slightly loose also noticed a 15amp fuse has blown & in my owners handbook it says a 25amp engine fan has been replaced with a 15amp

Could be the possible cause?..
Could be the possible cause?..
Le TVR said:
It looks like the standard Davies Craig fan there, which ISTR is a 150 watt rating, so probably 11 to 12 amps average.
15A fuse isn't going to give much of a margin and may have failed due to heat ageing?
Hmm yeah I recon so, should I just replace it with another 15amp fuse then in appose to the 25amp stated on there?15A fuse isn't going to give much of a margin and may have failed due to heat ageing?
Edited by greyhulk on Monday 10th August 18:47
Le TVR said:
It looks like the standard Davies Craig fan there, which ISTR is a 150 watt rating, so probably 11 to 12 amps average.
15A fuse isn't going to give much of a margin and may have failed due to heat ageing?
Hmm yeah I recon so, so should I just replace it with another 15amp fuse then in appose to the 25amp stated on there?15A fuse isn't going to give much of a margin and may have failed due to heat ageing?
Edited by greyhulk on Monday 10th August 18:48
The fuse is there to protect the wiring. Therefore, I'd stick with the 25A: there's no advantage in going lower.
Here's the Littelfuse data sheet for the ATO fuse Clicky.
You can see that the 15 and 25A fuses are designed to carry 110% of their rated current (16.5 and 27.5A) for 360000 seconds or 100 hours MINIMUM i.e. they are allowed to operate ("blow") at 100 hours and 1 second.
What this doesn't tell you is that the test is carried out using a special fuseholder which is probably rather better than yours at getting heat away from the fuse element. Derate a bit for this, derate again for ambient temperature (see chart), and derate again for the repeated fan starting current surge, and you can see that the 15A must be pretty marginal.
I hope this helps: I was on the team that introduced the blade fuse to European manufacturers about 100 years ago, so I know somewhat of which I speak.
Here's the Littelfuse data sheet for the ATO fuse Clicky.
You can see that the 15 and 25A fuses are designed to carry 110% of their rated current (16.5 and 27.5A) for 360000 seconds or 100 hours MINIMUM i.e. they are allowed to operate ("blow") at 100 hours and 1 second.
What this doesn't tell you is that the test is carried out using a special fuseholder which is probably rather better than yours at getting heat away from the fuse element. Derate a bit for this, derate again for ambient temperature (see chart), and derate again for the repeated fan starting current surge, and you can see that the 15A must be pretty marginal.
I hope this helps: I was on the team that introduced the blade fuse to European manufacturers about 100 years ago, so I know somewhat of which I speak.
Should definitely be a 25amp fuse. While you are at the fuse board have a look at the back and see if there is any sign of overheating where that fuse fits. If so you may have to take that circuit out of the fuse box and fit an in-line fuse instead. The fuse only serves the cooling fan and the wire carrying the power from the fuse whould be pink.
The feed to the otter switch should be a brown wire with a light green tracer. If it is any other colour then you will need to check if anyone might have 'bodged' the wiring. The other wire at the otter switch whould be a black wire to earth.
The feed to the otter switch should be a brown wire with a light green tracer. If it is any other colour then you will need to check if anyone might have 'bodged' the wiring. The other wire at the otter switch whould be a black wire to earth.
Edited by greymrj on Monday 10th August 21:43
Some after market fuses are real tat! they are made from thinner metal so the blades won't be tight in the holder which is quite possibly a bit loose with age anyway.
Read a post on PH some time ago where a guy had tested (don't know how exactly) a selection of cheapo fuses, 5 to 30 amps and they all blew at 30 amps!
If you ever go to a a Scrap Yard try and grab a few original quality fuses while no one's looking

There are loads of suppliers on fleabay offering 'Genuine Littelfuse ATO fuses' at around 10p each in quantity. However, there have always been 'Chinese copy' manufacturers whose products are always inferior (I used to test thousands of them!). Why not scrounge cheapos for testing, but then replace with quality fuses to avoid trouble down the line?
Littelfuse ATO (the originals) or Bussmann ATC are the ones to go for. I have no connection with either of these companies except as a disgruntled former employee of both. But the products are fine.
Littelfuse ATO (the originals) or Bussmann ATC are the ones to go for. I have no connection with either of these companies except as a disgruntled former employee of both. But the products are fine.
Gassing Station | S Series | Top of Page | What's New | My Stuff



