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Discussion Starter #1
Hello guys,


Now that the colder days have came, I have noticed that my engine temp rarely goes over 70 degrees (according to the gauge). For the 2 years I own the car it never went over 85-87 (going uphill in the summer when it is 40 degress outside) and it mostly sticks to 70 hot or cold. The reason I am worried is that last week it was snowing really badly and I had my heating turned on to the max as well as my ventilation in an attempt to defrost my windscreen, when going downhill my engine temp decreased to like 60 degrees (according to the gauge), I was going downhill with no throttle and my heating and ventilation to the max.


So I read the thread posted on your forums about testing the thermostat. However I wasn't sure about the outcome of the test. That's why I'm posting this.

This test took place over the course of like 20-30 mins. It was around 0 deg this morning. I started the car and let it run. On the picture attached I numbered the hoses related. Hose 1 started to heat pretty quickly, hose 2 was cold. It took like 10 mins of idling for the gauge to move from the bottom to like 55-60 degrees. Hose 1 was even hotter while the hose 2 was still cold. I wanted to speed the process up a bit so I applied some throttle and run the engine on 2k rpm and temp went up fast to 80 degrees, after that I let it idle a bit more, I saw the temperature decrease and the hose 2 was getting hotter too. Temp went down to 70 and stood there, I let it idle for another 5-10 mins and temp stood on 70 degrees mark.



Thank you for reading this. Can you tell me is there something wrong with my thermostat or my temp sensor/gauge? I like to have my car in the best condition possible so I would like to take care of it if there is something wrong.
 

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the thermostat still closes, if hose 2 stayed cold until 80-ish degrees. The gauges aren't too accurate either, but the important part is hose 2 stays cold then suddenly get hot. No gradual rising of the temperature.

Without throttle your heater will pull all the heat out of the engine, it's normal that the temp will drop.
 

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Also remember that the 147 has an odd way of showing engine temperature on the dash gauge. It isn't entirely linear as you might expect. Instead it's supposed to show 90C whenever the engine temperature is between 80-100C. So if the engine temperature hits 79 the gauge will suddenly drop from 90 to <80 very quickly making it look like the temperature is changing rapidly when in fact it isn't, just the way the gauge works. If your gauge is inaccurate it may be showing 80C rather than 90, so your 70 could in fact be closer to 80. Check with engine diagnostics to see the real engine temperature reported by the sender.

Also, if you've blanked or disabled the EGR the engine will struggle to maintain temperature on cold days when under light load with the heater on, just not enough residual heat produced to maintain normal engine temperature. The EGR flow seems to dump a fair amount of heat to the coolant via the EGR cooler.
 

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Discussion Starter #4
Thanks guys for your replies. You have been a great help.


Didn't blank the EGR, but thanks for the tip, also great info about the scale linearity.
 

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My temperature gauge never passes 80oC even with a new thermostat. I do however have the egr blanked. I replaced it when I was getting no hot air in the car. The mpg was also significantly improved. The part was about £70 and took me plenty of time to fit but I would expect a garage to charge 1hr labour.
 

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I am about to change the thermostat on an 8v , and it's obvious that the large top hose gets warm far too early , I'm hoping that your arrow is pointing to the top hose out of the radiator and not some small hose.
 

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MY advice is either get MES software and see what is really happening or fit a new stat. The top hose test will tell you if your stat is opening quickly but it won't tell you if it is opening early. I have had a few where the top hose test would suggest all is well but MES software shows otherwise and changing the thermostat improves the temp on the gauge, heater and demister.
 

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Yes my car was checked with my MES , but it was also obvious that the top hose shouldn't be warm from start up .
 
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