Jumping Temp Needle - Opinions?
Discussion
About 3/4 of the way to work this morning (I know, I know - don't use it for commuting!!!) I was held up at a T-Junction for about 2 or 3 minutes. Was not really paying attention to guages, just waiting for a gap to appear.
Then I heard a "tink" noise and noticed that the temp guage was jumping. It looked pretty random and it only did it twice then settled. Didn't do it again in the rest of the journey and temps were good all the way.
So, newbie question, should I worry? Just got it back from Dulfords after spending £
and she's be running beautifully apart from this twitch.
Any ideas?
Then I heard a "tink" noise and noticed that the temp guage was jumping. It looked pretty random and it only did it twice then settled. Didn't do it again in the rest of the journey and temps were good all the way.
So, newbie question, should I worry? Just got it back from Dulfords after spending £
and she's be running beautifully apart from this twitch.Any ideas?
Actually chaps I dont think its an airlock.
The temp gauges are capillary - much better than digital. What you are seeing when the gauge flickers is the thermostat opening and letting hot water/coolant flow round the system. It then flicks back down when the temperature equalizes.
I was worried about it on mine but its perfectly normal according to Mat @ Sebrings.
The temp gauges are capillary - much better than digital. What you are seeing when the gauge flickers is the thermostat opening and letting hot water/coolant flow round the system. It then flicks back down when the temperature equalizes.
I was worried about it on mine but its perfectly normal according to Mat @ Sebrings.
Edited by markh1 on Tuesday 29th April 12:09
markh1 said:
Actually chaps I dont think its an airlock.
The temp gauges are capillary - much better than digital. What you are seeing when the gauge flickers is the thermostat opening and letting hot water/coolant flow round the system. It then flicks back down when the temperature equalizes.
I was worried about it on mine but its perfectly normal according to Mat @ Sebrings.
The thermostat only opens once, then it remains open. The needle 'flicking' up and down is not normal. If it does, you can pretty much guarantee it's cause by an airlock.The temp gauges are capillary - much better than digital. What you are seeing when the gauge flickers is the thermostat opening and letting hot water/coolant flow round the system. It then flicks back down when the temperature equalizes.
I was worried about it on mine but its perfectly normal according to Mat @ Sebrings.
Edited by markh1 on Tuesday 29th April 12:09
I've never been convinced by teh airlock theory. The thermostat defo doesn't just open once and stay open, it's constantly opening and closing, or somewhere inbetween depending on what temp of water is flowing past it .. for instance on a very cold morning it might open, then get a load of very cold water going past so shuts closed again, then opens, the shuts closed again until the temp of the water in the rad gradually increases .. it might only take one or two opening/closing cycles but it does definately happen. The thermostat isn't just open or closed like a switch, it's a constantly varying flow rate but it's only a feedback system based on water which is aready too hot or too cold and takes time to react and time to minimise temperature fluctuations. I've maybe not explained it very well, but you get the idea?
Jools, you must be as bored as me 
........
Put a Thermostat in a pan of water and heat it up, and it gradually opens at the pre-set temperature. Turn the pan off and it gradually closes. It doesn't just instantly open and shut, and neither does the water temperature in an engine, suddenly shoot up in temperature. A Thermostat also acts as a kind of 'flow-control' for water circulating around the engine. The needle suddenly flicking up, then dropping, is caused by an air lock. The AJP does actually tend to create air in the system, so bleeding it occasionally is sound practice. A cooling system that isn't 100% air tight will expel small amounts of coolant when the engine is running, and when the system cools down, it will 'suck' air in, and this will create an air-lock.
........Put a Thermostat in a pan of water and heat it up, and it gradually opens at the pre-set temperature. Turn the pan off and it gradually closes. It doesn't just instantly open and shut, and neither does the water temperature in an engine, suddenly shoot up in temperature. A Thermostat also acts as a kind of 'flow-control' for water circulating around the engine. The needle suddenly flicking up, then dropping, is caused by an air lock. The AJP does actually tend to create air in the system, so bleeding it occasionally is sound practice. A cooling system that isn't 100% air tight will expel small amounts of coolant when the engine is running, and when the system cools down, it will 'suck' air in, and this will create an air-lock.
It's not an airlock in the cooling system. There's no way the capillary tube could respond to a varying temperatue in that portion of pipe that quickly.
Personnaly I think it's a design flaw with the tube and gauge itself. No idea what but that's my theory.
Didn't know this though, keep bend radii over 1" and have 3-4 coils in the line. This may be to absorb vibration and stop fractures though.
Personnaly I think it's a design flaw with the tube and gauge itself. No idea what but that's my theory.
Didn't know this though, keep bend radii over 1" and have 3-4 coils in the line. This may be to absorb vibration and stop fractures though.
Maybe it isnt an Airlock, but you have 2 options,
A Spend days discussing, arguing, theorising, putting forward opinions, dismissing other peoples advice and pontificating over the possible causes.
B Bleed the system, if it cures the problem - great. If it doesn't then at least we have isolated one of the possible causes and can start looking at other possiblities.
Up to you what you do !!
A Spend days discussing, arguing, theorising, putting forward opinions, dismissing other peoples advice and pontificating over the possible causes.
B Bleed the system, if it cures the problem - great. If it doesn't then at least we have isolated one of the possible causes and can start looking at other possiblities.
Up to you what you do !!
Edited by JensenA on Tuesday 29th April 22:48
If it isnt an airlock why does bleeding the system help? Surely if it was a thermostat or vibration it would do it all the time?
I'm with the others in the airlock theory group
Everytime mine did it I bled it and it went away for another few months.
GOD I MISS IT
Vettes not missed a beat and gets a regular thashing and still I miss the Cerb. Hands up whos got it? Hand her back you've had it long enough matey!!!
I'm with the others in the airlock theory group
Everytime mine did it I bled it and it went away for another few months.
GOD I MISS IT
Vettes not missed a beat and gets a regular thashing and still I miss the Cerb. Hands up whos got it? Hand her back you've had it long enough matey!!!
Thanks Gents - a smorgasboard of options!
Haven't had the problem again on either the trip back yesterday or going in and out of work today. But I bled it tonight anyway. If it happens again I'll add another entry to this thread.
Tyresmoke - left a message with Richard @ Dulford, but he hasn't got back to me yet.
Haven't had the problem again on either the trip back yesterday or going in and out of work today. But I bled it tonight anyway. If it happens again I'll add another entry to this thread.
Tyresmoke - left a message with Richard @ Dulford, but he hasn't got back to me yet.
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