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RJS
Jedi Warrior
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Hey,
In years past, my car would always run with temp needle right smack in the middle of the gauge, except when extremely hot ambient or sitting idling for a while. In those cases it would move about 3/4 up the gauge (mid way between normal and full hot).
However, late last year the gauge began indicating the engine was running cool. Fully warmed and under normal driving, the gauge is only reaching maybe 1/3 up the gauge. Other than that, car runs excellent as it had before. Spark plugs look great too. No complaints.
So, what could cause a change? The only two things which changed are:
1) I flushed the cooling system. When I did this I refilled it with 55% water, 40% anti-freeze and 5% Water Wetter (water and Water Wetter are much more efficient in heat transfer). In the past I had used a 50/50 mix, no Water Wetter. Also, for the first time, I jacked up the front of the car, opened the radiator cap and "burped" all the air from the system. When I did this, it actually took a fair bit more to fill the system.
2) I switched from using 20W50 to 10W40 oil.
Even if these changes led to cooler running, I would expect the T-stat to keep the temp regular regardless of these two changes - I have a 180 degree T-stat.
I do recall this happened to me when I first got the car 12 years ago. A change of the temp sending unit in the thermostat housing was a quick and cheap fix (5 minutes and $5). I'll start there again and perhaps check the voltage stabilizer (although my fuel gas reads fine). Should I suspect a bad T-stat? I understood they fail "closed" which leads to over-heating.
Thanks
Bob
PS: anything wrong with an engine running "cool", if that is the case?
In years past, my car would always run with temp needle right smack in the middle of the gauge, except when extremely hot ambient or sitting idling for a while. In those cases it would move about 3/4 up the gauge (mid way between normal and full hot).
However, late last year the gauge began indicating the engine was running cool. Fully warmed and under normal driving, the gauge is only reaching maybe 1/3 up the gauge. Other than that, car runs excellent as it had before. Spark plugs look great too. No complaints.
So, what could cause a change? The only two things which changed are:
1) I flushed the cooling system. When I did this I refilled it with 55% water, 40% anti-freeze and 5% Water Wetter (water and Water Wetter are much more efficient in heat transfer). In the past I had used a 50/50 mix, no Water Wetter. Also, for the first time, I jacked up the front of the car, opened the radiator cap and "burped" all the air from the system. When I did this, it actually took a fair bit more to fill the system.
2) I switched from using 20W50 to 10W40 oil.
Even if these changes led to cooler running, I would expect the T-stat to keep the temp regular regardless of these two changes - I have a 180 degree T-stat.
I do recall this happened to me when I first got the car 12 years ago. A change of the temp sending unit in the thermostat housing was a quick and cheap fix (5 minutes and $5). I'll start there again and perhaps check the voltage stabilizer (although my fuel gas reads fine). Should I suspect a bad T-stat? I understood they fail "closed" which leads to over-heating.
Thanks
Bob
PS: anything wrong with an engine running "cool", if that is the case?
That sender is not the very best item Smiths ever produced. :wink: (But to be fair, many of those senders have lasted 40+ years, so....)
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