Club 80-90 Forums

Although I have never suffered overheating problems (sorry for your woes djasse hope you get it sorted) it is not uncommon for me to put the heater on full when climbing hills in the middle of summer with the windows open and copious amounts of water to drink due to a lack of confidence in the temp gauge, most people seem to claim different readings with theirs, anyway my sensor was faulty so a replacement arrived today, before I removed the old one I connected the new one to the wires, stuck the kettle on, grabbed a digital thermometer, dipped the new sensor in the kettle. Now I now where to start to sweat when the needle gets to high, 100 degrees is just past the light and 90 just before.

NicBeeee wrote:Although I have never suffered overheating problems it is not uncommon for me to put the heater on full when climbing hills in the middle of summer with the windows open and copious amounts of water to drink due to a lack of confidence in the temp gauge, most people seem to claim different readings with theirs, anyway my sensor was faulty so a replacement arrived today, before I removed the old one I connected the new one to the wires, stuck the kettle on, grabbed a digital thermometer, dipped the new sensor in the kettle. Now I now where to start to sweat when the needle gets to high, 100 degrees is just past the light and 90 just before.

...your system is under pressure so the boiling point temperature will be higher.
Thermostat opens at 87deg, but that's way off any boiling point in a pressurised cooling system

kevtherev wrote:

...your system is under pressure so the boiling point temperature will be higher.
Thermostat opens at 87deg, but that's way off any boiling point in a pressurised cooling system[/quote]

Not worrying about the van boiling over just running to hot, i like to keep it at around 100

Why are you worried about driving up hills in hot weather? When I'm driving along the temperature never rises to the point where the cooling fan kicks in. My fan only kicks in when I'm stuck in traffic having been hammering along a motorway. Does your fan not work?

NicBeeee wrote:

kevtherev wrote: ...your system is under pressure so the boiling point temperature will be higher.
Thermostat opens at 87deg, but that's way off any boiling point in a pressurised cooling system

Not worrying about the van boiling over just running to hot, i like to keep it at around 100

The thermostat keeps it at 87
If it isn't at 87 then the fans come on at 91.. and then 103.
these are normal conditions for your cooling system

Ralf85 wrote:Why are you worried about driving up hills in hot weather? When I'm driving along the temperature never rises to the point where the cooling fan kicks in. My fan only kicks in when I'm stuck in traffic having been hammering along a motorway. Does your fan not work?

Nope everything works as should, the needle sits at exactly the right temps so I know the thermostat is ok, the fan kicks in at exactly the right temps so i know its working fine too, I didnt but now I do. The simple test I was trying to explain was not as a fault finding exercise but as a way of reassurance and a more accurate understanding of the position of the needle. I and I am sure others have seen several threads were people have asked where does your needle sit on the gauge and why does theres sit before or after light and is our van running to hot or to cool.

So from now on you can relax leave your heating off and enjoy the journey. Excellent!

Mine sits to right of centre since I replaced thermostat although in part it depends on how accurate guage is I suppose. Never gets higher than that and fan will kick in low speed if I do end up stuck in traffic. The only time high speed kicks in is if I flick the chicken switch. There are split opinions on the value of a chicken switch but its nice to have it all the same.

kevtherev wrote:The thermostat keeps it at 87
If it isn't at 87 then the fans come on at 91.. and then 103.
these are normal conditions for your cooling system

^ This, with bells on.

If the rad and fan aren't doing their jobs properly, a better use of time and money would be to fix the problem, rather than work around it.

20 days after the previous post

I bought one of these to test this subject



I have had great fun randomly pointing it at things

My temp gauge sits at only about 1/3rd the way up. It gets there pretty quickly and once there, stays there, unless I am in traffic jams, in which case it climbs to just above the led and the rad fan comes on. I have swapped the sender and checked the 10 volt feed to the gauge(s)= all good, so I assumed it was just the actual gauge reading a bit low and lived with it. However when I bought the above pictured infra red thermometer (at only £8 - Amazon link) on pointing it at the black plastic stat housing, engine fully warmed up, it measures only 72 degrees. I checked against a mates new(ish) car and his top hose measured 86 degrees. I am now assuming that my thermostat, whilst not stuck open, is opening at too low a temperature (faulty), so I guess I will have to buy a new stat and try it. My (later style) stat housing and bolts are in good clean nick, so I am hoping I have no issues there!

ghost123uk wrote:20 days after the previous post

I bought one of these to test this subject

That looks fun - might have to get one myself for a bit of tinkering.

kevtherev wrote:The thermostat keeps it at 87
If it isn't at 87 then the fans come on at 91.. and then 103.
these are normal conditions for your cooling system

I've never seen any mention of the seasonal dependence of the 'nominal' needle position, but mine definitely depends on the weather. In the sort of ambient temperatures we have at the moment (8-10 degrees) my temperature needle sits on the right hand edge of the warning light - this is with the engine warmed up fully, but without the fan running. In hotter summer weather, it will tend to sit maybe quarter of an inch further to the right - again, without the fan kicking in. The fan does kick in if it goes much further to the right though, e.g. in traffic queues.

I'm happy that this variation in the position of the needle corresponds to a range of temperatures - from the temperature that the thermostat opens to the temperature that the fan comes on. And it makes sense to me that the ambient temperature has an effect on the nominal running temperature of the coolant - in fact it tells me that the system is optimally designed with the right amount of 'normally aspirated' cooling capacity for a range of weather.

But looking at Kev's figures, I'm slightly surprised that this quarter inch of needle movement covers only 4 degrees (87 to 91). My '83 van has only a single fan speed I think - does anyone know what temperature this kicks in at?

CJH wrote:
I've never seen any mention of the seasonal dependence of the 'nominal' needle position, but mine definitely depends on the weather. In the sort of ambient temperatures we have at the moment (8-10 degrees) my temperature needle sits on the right hand edge of the warning light - this is with the engine warmed up fully, but without the fan running. In hotter summer weather, it will tend to sit maybe quarter of an inch further to the right.

And it makes sense to me that the ambient temperature has an effect on the nominal running temperature of the coolant

In theory, by the nature of what a thermostat does, the ambient temperature should have no effect at all on the temperature of the coolant flowing around the actual engine. The stat is there specifically to maintain a temp of 87 degrees, which is the optimum temperature for the engines efficiency.

yep, mine sits dead centre whatever the weather

ghost123uk wrote: In theory, by the nature of what a thermostat does, the ambient temperature should have no effect at all on the temperature of the coolant flowing around the actual engine. The stat is there specifically to maintain a temp of 87 degrees, which is the optimum temperature for the engines efficiency.

I see what you're saying, but I can also see a different side. If the cooling system doesn't have quite enough power to keep the temperature down to 87 degrees, then the thermostat will always be open (e.g. on a hot day). So maybe that's what my varying needle is telling me in fact - maybe the right hand edge of the warning light represents 87 degrees in my van, and on a hot day I could do with more cooling power from the radiator - maybe it's a bit furred up or it's the older thinner type. Touch wood I've not had an issue with higher temperatures - is there really much loss of engine efficiency a few degrees above that? I'd still be interested to know what the cut-in temperature is for an old single-speed fan.

Yes I see your point. There will be times on a hot day, and if insufficient air is cooling the radiator, that the temp will rise and the rad fan then kicks in to help with cooling.

Re efficiency, there is a designed range of temps that create maximum efficiency, I would guess that this is in the approximate range of 88 degrees to 100 degrees (stands by to be corrected ) so a slightly hotter engine (than the stats 88 degree control) is not going to be outside those parameters