How Important Is The Thermostat?

[YALA]

ah been haggling about this topic for the last week..my problem was quite opposite the cab never came up to the half mark in 3 years of owning it except on the highway and recently been passing the half mark after a short 6k mark, checked everything except for a radiator block and thermo which i left for this weekend. Any clue on how to check if the thermo works fine ? like cold start will you see coolant circulating when you pop the radiator cap or do i need to take it apart and do a test.

[YALA]

Also anytime a bass says to take off something that its not really necessary i always tell him there is a reason behind that item been put there in the first place so if its removed due to non functioning then replace it

[trinity]

I just can't believe the above explanation coming from a place like U***O. Now that you have the gadget in hand see if the water path is open. Then drop it into a jug filled with boiling water and observe the valve opening slowly. If you have a thermometer you can measure the temperature and see if begins to open at around 50C and fully open when the temperature gets to around 70 - 80C (these figures may vary depending on the thermostat model). For an animation go to

Yes machan.. if i hadn't read about the importance of the thermoastat here, i would have defa trusted their word. Thanks for your suggestion machan. I'm unable to view the video as the office has you tube blocked. Will go home and give it a try.

[VVTi]

Yes machan.. if i hadn't read about the importance of the thermoastat here, i would have defa trusted their word. Thanks for your suggestion machan. I'm unable to view the video as the office has you tube blocked. Will go home and give it a try.

What I would suggest is to replace it with a brand new part. Testing as Rumesh said will confirm the the operational condition of the thermostat. YOu might as well drop in a new one while you are at it. If its 7K at the agents, it is surely much less outside. It is a DIY job anyway.

[VVTi]

ah been haggling about this topic for the last week..my problem was quite opposite the cab never came up to the half mark in 3 years of owning it except on the highway and recently been passing the half mark after a short 6k mark, checked everything except for a radiator block and thermo which i left for this weekend. Any clue on how to check if the thermo works fine ? like cold start will you see coolant circulating when you pop the radiator cap or do i need to take it apart and do a test.

Without removing the stat, you can actually check. On a cold start, open the radiator cap and watch and wait. If around the normal halfway point on the gauge you see the water churning that means the thermostat opened. Depending on your vehicle, the fans should come on soon after this point. Or track the hose that comes from the thermostat housing and touch it and see if its warm. Ideall it should be cooler than the rest of the hoses if the thermostat is there.

Make sure you replace the water that spilled during this test.

[VVTi]

I just can't believe the above explanation coming from a place like U***O. Now that you have the gadget in hand see if the water path is open. Then drop it into a jug filled with boiling water and observe the valve opening slowly. If you have a thermometer you can measure the temperature and see if begins to open at around 50C and fully open when the temperature gets to around 70 - 80C (these figures may vary depending on the thermostat model). For an animation go to

I couldn't test mine this way as it was never there in the first place. LOL.

Don't be surprised with UNIMO's comment, I got the same harrang from my agents. They dont even stock it saying no one buys. Can you beleive it??? And I am still waiting for Borella Motors to get beck to me with a new part... LOL. I already got it delivered from SGP and is running with it.

[trinity]

What I would suggest is to replace it with a brand new part. Testing as Rumesh said will confirm the the operational condition of the thermostat. YOu might as well drop in a new one while you are at it. If its 7K at the agents, it is surely much less outside. It is a DIY job anyway.

Yes machan if i can find a brand new part from the out side for a lesser amout, will definitely replace it. I doubt whether these are available outside though. Anyway, need to do something soon as the car drinks petrol these days. Earlier i was suspecting the carburator but i should tick this ok and then see if she is still thirsty.

Just sharing, after removing the thermostat, it took around 10 minutes to fans to kick in. This was checked at the workshop before they let me take the car.

Edited March 5, 2014 by trinity

[VVTi]

Yes machan if i can find a brand new part from the out side for a lesser amout, will definitely replace it. I doubt whether these are available outside though. Anyway, need to do something soon as the car drinks petrol these days. Earlier i was suspecting the carburator but i should tick this ok and then see if she is still thirsty.

What is your vehicle? Chek on Ebay. If you have the sample a small walk around Panchi might sort you out.

[trinity]

What is your vehicle? Chek on Ebay. If you have the sample a small walk around Panchi might sort you out.

Lancer CS1 2001 model. will do. thanks

[Rumesh88]

Yes machan.. if i hadn't read about the importance of the thermoastat here, i would have defa trusted their word. Thanks for your suggestion machan. I'm unable to view the video as the office has you tube blocked. Will go home and give it a try.

Before you set out to replace the thermostat as VVTi has quite correctly suggested it is worth having a look at the operating point of radiator fan motor as well, particularly if the fan motor thermostat switch is a aftermarket one. Ideally this would not matter if the radiator thermostat operate correctly because the coolant flow begins only after the temp reaching a certain point. But still it may be worthwhile checking if the fan motor kicks in well before the coolant reach half mark.

[VVTi]

Before you set out to replace the thermostat as VVTi has quite correctly suggested it is worth having a look at the operating point of radiator fan motor as well, particularly if the fan motor thermostat switch is a aftermarket one. Ideally this would not matter if the radiator thermostat operate correctly because the coolant flow begins only after the temp reaching a certain point. But still it may be worthwhile checking if the fan motor kicks in well before the coolant reach half mark.

Funny you should mention the radiator fan operation. My stat starts to open at 78, and fully opens at 96. However, the fans come on at around 99-100 degrees. I am playing it safe and ordered Coolant Temp sensor as well. Should be getting it deleivered tomorrow. It is a 3 wire uinit where each wires is connected to the ECU, gauge and fan relay. Either of the 3 circuits failing will cause an issue. So getting that done as well.

[trinity]

Before you set out to replace the thermostat as VVTi has quite correctly suggested it is worth having a look at the operating point of radiator fan motor as well, particularly if the fan motor thermostat switch is a aftermarket one. Ideally this would not matter if the radiator thermostat operate correctly because the coolant flow begins only after the temp reaching a certain point. But still it may be worthwhile checking if the fan motor kicks in well before the coolant reach half mark.

Thanks Rumesh.. at the risk of sounding stupid, does normal dignostic scanners indicate these figures?

[c1nder]

I don't know about other engines but the 4age 20v Blacktop it's quite another story. When the 20v is cold the thermostat shuts off the path to the radiator and the water pump circulates water within the block. When it's hot and fully open it shuts off the internal circulation path from the rounded part at the bottom of the thermostat. So it draws water from the radiator.

This means that without a thermostat the 20v tends to overheat since the pump finds it easier to circulate water within the engine block and cannot run, just builds up heat.

And this is what I found sometime back when I bought the car . A maka baas had forced it open to get around this issue.

Edited March 5, 2014 by c1nder

[Rumesh88]

Thanks Rumesh.. at the risk of sounding stupid, does normal dignostic scanners indicate these figures?

Of course you can read ECT sensor for engine temperature on OBD port but you need not go that far. You can just observe the radiator fan as the engine warms up and see at what point the fan kicks in.

[VVTi]

I don't know about other engines but the 4age 20v Blacktop it's quite another story. When the 20v is cold the thermostat shuts off the path to the radiator and the water pump circulates water within the block. When it's hot and fully open it shuts off the internal circulation path from the rounded part at the bottom of the thermostat. So it draws water from the radiator.

This means that without a thermostat the 20v tends to overheat since the pump finds it easier to circulate water within the engine block and cannot run, just builds up heat.

And this is what I found sometime back when I bought the car . A maka baas had forced it open to get around this issue.

That's more or less the manner it works elsewhere too.

ROFL on the toothbrush.. Recommended by dentists I suppose.

[trinity]

Okay..

Yesterday I tested the thermostat as suggested. Valve started opening at the point when the small water bubbles started to come. Then it kept opening right to the boiling point and kept open. Then I mixed cold water to see if the valve is closing and it did. Unfortunately I did not have a thermo meter with me to check the figures. So does this mean thermostat functions as it should?

Or is it better to change it anyway (if I could find a one outside for cheap)

Also below are the temp guage indications before and after running with thermostat removed. Appreciate if you could share your thoughts on 1, 2, & 3.

Edited March 7, 2014 by trinity

[VVTi]

Ideally it should start opening before water starts boiling. Opening at the point means the coolant ahs reached boiling point. Mine starts opeing at 78-80 and is fully open by 96 degrees.

Put a new one in.

I was thinking, if UniMo said 7k for replacing, is that with the coolant and labour also? If that is so, then it might be a good deal.

Update on mine : Just collected the genuine Coolant Temp sensor. Will be putting it in tomorrow morning as to replace it is a PITA. Need to remove the alternator to reach the CTS. Not advisabe when engine is hot.

[Davy]

Okay..

Yesterday I tested the thermostat as suggested. Valve started opening at the point when the small water bubbles started to come. Then it kept opening right to the boiling point and kept open. Then I mixed cold water to see if the valve is closing and it did. Unfortunately I did not have a thermo meter with me to check the figures. So does this mean thermostat functions as it should?

Or is it better to change it anyway (if I could find a one outside for cheap)

Also below are the temp guage indications before and after running with thermostat removed. Appreciate if you could share your thoughts on 1, 2, & 3.

As per the engine workshop manual for the 4G1 engine series, the opening temperature of the thermostat valve is 88 ± 1.5 Celsius and come to a fully opened state at 100 Celsius. The amount of lift should be 8.5mm or higher. If any of the above parameters are not upto spec, the thermostat valve should be replaced. A visual inspection alone will not cut it in my opinion.

I'd say go genuine to ensure proper operation. A friend of mine told me that he got down one from amayama.com for about 2600 LKR with just 5USD shipping.

[Rumesh88]

Your thermostat should be OK IMO ( 4G13 specs say it begins to open at 82C and go on until 95C. I'm sorry I was a bit too lazy to read things earlier). Does your radiator fan kick in (if not already operating after a run) when you keep the car idle for about one minute after a run assuming your temp gauge is at quarter mark? Temp gauge is a completely independent mechanism (I mean electrically from the radiator fan and ECU) and hence if the fan comes on even at the quarter mark it means that the gauge calibration must be a bit off. There are three things here - the thermostat, ECT sensor and the ECT gauge unit. We have to make sure two of them are OK before passing judgement on the remaining. Hence the point at which the fan starts is necessary. (While typing this comment happened to see Davy's reply and strange why some of the figures differ from mine but that's trivial).

[trinity]

Ideally it should start opening before water starts boiling. Opening at the point means the coolant ahs reached boiling point. Mine starts opeing at 78-80 and is fully open by 96 degrees.

Put a new one in.

I was thinking, if UniMo said 7k for replacing, is that with the coolant and labour also? If that is so, then it might be a good deal.

Update on mine : Just collected the genuine Coolant Temp sensor. Will be putting it in tomorrow morning as to replace it is a PITA. Need to remove the alternator to reach the CTS. Not advisabe when engine is hot.

No machan, its for the valve only. Coolant and labour charges are additional. However they didn't charge me a cent for removing the part. Refilled water and asked me to run about a week without with the thermostat and come back to put in a new one if not satisfied with the results.

[trinity]

As per the engine workshop manual for the 4G1 engine series, the opening temperature of the thermostat valve is 88 ± 1.5 Celsius and come to a fully opened state at 100 Celsius. The amount of lift should be 8.5mm or higher. If any of the above parameters are not upto spec, the thermostat valve should be replaced. A visual inspection alone will not cut it in my opinion.

I'd say go genuine to ensure proper operation. A friend of mine told me that he got down one from amayama.com for about 2600 LKR with just 5USD shipping.

Davy

Thanks for the info machan.. Did receive your text also sorry couldnt reply. Could you ask your friend how long did it take to receive the part. Cuz at the rate i'm burning fuel, i really need to put a solution to this as soon as possible to prevent me from going bankrupt.

On a side note, although valve opened till boiling point, i doubt it opened 8.5mm cuz the visible gap was like 4 - 5mms.

Edited March 7, 2014 by trinity

[VVTi]

No machan, its for the valve only. Coolant and labour charges are additional. However they didn't charge me a cent for removing the part. Refilled water and asked me to run about a week without with the thermostat and come back to put in a new one if not satisfied with the results.

Ok, will they fix a part you bring from the outside? Actually, you can DIY...

[trinity]

Your thermostat should be OK IMO ( 4G13 specs say it begins to open at 82C and go on until 95C. I'm sorry I was a bit too lazy to read things earlier). Does your radiator fan kick in (if not already operating after a run) when you keep the car idle for about one minute after a run assuming your temp gauge is at quarter mark? Temp gauge is a completely independent mechanism (I mean electrically from the radiator fan and ECU) and hence if the fan comes on even at the quarter mark it means that the gauge calibration must be a bit off. There are three things here - the thermostat, ECT sensor and the ECT gauge unit. We have to make sure two of them are OK before passing judgement on the remaining. Hence the point at which the fan starts is necessary. (While typing this comment happened to see Davy's reply and strange why some of the figures differ from mine but that's trivial).

Rumesh

This i wii check today and confirm machan. But on a cold start it took lot of time to kick in (say abot 10 15 mins) as observed after removing the thermostat at the agents. At that time gauge was nearing quarter point.

P.S VVTi I hope you dont mind me highjacking your thread

[trinity]

Ok, will they fix a part you bring from the outside? Actually, you can DIY...

Once i went to them to paste an emblem thinking that they will do it to manufacturer spec, although emblem was not bought from them they undertook to do the job. Pasted it like shit and charged Rs.400/- hi hi hi.. This however i have to ask. Anyway as you said, its a simple thing.

[VVTi]

Rumesh

This i wii check today and confirm machan. But on a cold start it took lot of time to kick in (say abot 10 15 mins) as observed after removing the thermostat at the agents. At that time gauge was nearing quarter point.

P.S VVTi I hope you dont mind me highjacking your thread

LOL, not at all. I am glad this discussion has got people thinking.

I hope our maka baases wont start removing 'stats off Hybrids too... ha ha ha ha!