Does a vehicle in our sub-saharan Africa need a thermostat ?
Hallo all, To the vehicle gurus... we have been having this debate after a vehicle overheated. At first we thought it was a faulty sensor, so we removed that... Then the situation got out of hand and the mechanics advised that the Thermostat was the problem, and it is common knowledge to remove the thermostat when it comes from winter countries to our good old sub-sahara.. This overheating problem occurs in rainy or cold situations - dont know why. But never when its hot, so on a level, the mechanics could be right. After removing the thermostat and reinstalling the heat sensor, the vehicle seems fine and does not overheat - however, I came across the article below on the net [who do we believe? experienced mechanics, or those who know why the thermostat was installed in the first place?] : Q: Can running without a thermostat cause overheating I was told that if the water circulates too fast it will not cool properly Is this possible and how? Running your engine without a thermostat will cause it to run hot. An engine will run cooler initially without a thermostat. After that IT WILL NOT! Why you ask? Again, physics. An engine running without the restriction of the thermostat in the system (remember, even when it's wide open there's still some restriction in the system caused by the thermostat's small opening) will not keep the coolant in the radiator long enough for the radiator to 'radiate' the heat. That is, the coolant must stay in the radiator for a certain amount of time to dissipate some of the heat it has absorbed from being in the engine block. The coolant is in the block. It's hot. It moves to the radiator and gets rid of some of the heat. If it moves through the radiator too FAST, without the restriction of the thermostat body, it won't get rid of as much heat. Basic Thermodynamics at play. http://wiki.answers.com/Q/Can_running_without_a_thermostat_cause_overheating...
*Disclaimer: I am not qualified enough in mechanics to be quoted here, but let me give my 2cts* Thermostats are there to detect when temp goes beyond a limit lets say to cold or too hot. in a car its for too hot. now if you car was built fo winter it might actually have both. that is when temps are below 1.(C) to warm up the coolant and allow combustion on engine start-up. Flow restriction; as you have mentioned thermo dynamics, the little i know tells me the decipation of heat needs the temperature difference to be large, thus the flow restriction you mention. Constant flow will mean coolant will evenly warm-up and stop cooling altogether. To have it or not: I don't know? but if your thermostat is for blocking coolant flow removing it is safer than having it faulty. if you have bypassed the thermostat then you have to watch your driving to keep the engine from burning out. recall some cars use the same thermostat to protect the engine from that. Important: mechanics will always opt for the quickest / cheapest solution that will make you happy, not the right one don't fall for this famous quote "*baba hiyo hai hitajiki, tunaweza toa ndio iache kukusumbua*" {translation: "*Sir that is not necessary we can remove it so that it stops bugging you*"} Ashford K. 2009/10/30 ndungu stephen <ndungustephen@gmail.com>
Hallo all,
To the vehicle gurus... we have been having this debate after a vehicle overheated. At first we thought it was a faulty sensor, so we removed that...
Then the situation got out of hand and the mechanics advised that the Thermostat was the problem, and it is common knowledge to remove the thermostat when it comes from winter countries to our good old sub-sahara..
This overheating problem occurs in rainy or cold situations - dont know why. But never when its hot, so on a level, the mechanics could be right.
After removing the thermostat and reinstalling the heat sensor, the vehicle seems fine and does not overheat - however, I came across the article below on the net [who do we believe? experienced mechanics, or those who know why the thermostat was installed in the first place?] :
Q: Can running without a thermostat cause overheating I was told that if the water circulates too fast it will not cool properly Is this possible and how? Running your engine without a thermostat will cause it to run hot. An engine will run cooler initially without a thermostat. After that IT WILL NOT! Why you ask? Again, physics. An engine running without the restriction of the thermostat in the system (remember, even when it's wide open there's still some restriction in the system caused by the thermostat's small opening) will not keep the coolant in the radiator long enough for the radiator to 'radiate' the heat. That is, the coolant must stay in the radiator for a certain amount of time to dissipate some of the heat it has absorbed from being in the engine block. The coolant is in the block. It's hot. It moves to the radiator and gets rid of some of the heat. If it moves through the radiator too FAST, without the restriction of the thermostat body, it won't get rid of as much heat. Basic Thermodynamics at play.
http://wiki.answers.com/Q/Can_running_without_a_thermostat_cause_overheating...
_______________________________________________ Skunkworks mailing list Skunkworks@lists.my.co.ke http://lists.my.co.ke/cgi-bin/mailman/listinfo/skunkworks ------------ Skunkworks Rules http://my.co.ke/phpbb/viewtopic.php?f=24&t=94 ------------ Other services @ http://my.co.ke Other lists ------------- Announce: http://lists.my.co.ke/cgi-bin/mailman/listinfo/skunkworks-announce Science: http://lists.my.co.ke/cgi-bin/mailman/listinfo/science kazi: http://lists.my.co.ke/cgi-bin/mailman/admin/kazi/general
@Ndungu, the thermostat is much debated.... :-) Am in a rush.....I'll give you my short opinion, why its needed and important : 1) Engine optimal temperature ensures less friction on moving parts 2) Engine Oil properties and correct viscosity are formulated for optimum temperature. 3) Fuel deposits. Cooler charge intake is better but achieved at optimum temperature. 4) On all Fuel injection engines, engine temperature sensor regulates excess fuel intake. Thus with no thermo, engine fuel intake will always be RICH until temp is reached, thus excess fuel burned and economy not much. More wear and tear at colder temps. 5) Your car front wind shield "defroster". You need the heater to remove moisture during rainy seasons. I've listed things in a very basic way.... :-)
@Ndungu, me thots..... you should get a professional to look into your query.. Try AA of Kenya. :-) On Fri, Oct 30, 2009 at 5:54 PM, aki <aki275@googlemail.com> wrote:
@Ndungu,
the thermostat is much debated.... :-)
Am in a rush.....I'll give you my short opinion, why its needed and important :
1) Engine optimal temperature ensures less friction on moving parts
2) Engine Oil properties and correct viscosity are formulated for optimum temperature.
3) Fuel deposits. Cooler charge intake is better but achieved at optimum temperature.
4) On all Fuel injection engines, engine temperature sensor regulates excess fuel intake. Thus with no thermo, engine fuel intake will always be RICH until temp is reached, thus excess fuel burned and economy not much. More wear and tear at colder temps.
5) Your car front wind shield "defroster". You need the heater to remove moisture during rainy seasons.
I've listed things in a very basic way.... :-)
Thanks for the info guys, i definitely will ... I thought that thermostat was put there for a reason - will opt to buy and replace it [since we think it went faulty].... That mechanic myth i think is officially busted, ama ?
On Fri, Oct 30, 2009 at 6:23 PM, ndungu stephen <ndungustephen@gmail.com>wrote:
Thanks for the info guys, i definitely will ...
I thought that thermostat was put there for a reason - will opt to buy and replace it [since we think it went faulty]....
That mechanic myth i think is officially busted, ama ?
@Ndungu, I;m sharing my personal opinion so nothing to go by....
Each time I've bought a car, 2 things are changed from the time of purchase. Thermostat and timing belt. And pls do buy a thermostat from the company to maintain original parts or get it brought in. To test a thermostat, you need a thermometer and get the reading of the thermo housing eg 72, 74 deg etc. Then boil water and let it cool to about that temp. Pour into a can and place thermostat and thermometer into the can. Slowly pour hot water, until the water in the can reaches the thermostat temp. You will see the valve lift at the correct temp. If you want to do semi-arid and desert stuff, then get a larger radiator fitted with twin fans. But a thermo would still need to be in engine. Lets start with the efi cold engine with a thermo : - Engine start, engine temp sensor sends a signal to ICU unit to enrich fuel. This action is similar to " pulling on the choke lever " on older engines. Sometimes, if you want better performance from an engine, you can cheat it by playing with the engine temp sensor, fooling it to think the engine is cold. The ICU unit will allow more injection of fuel. If you notice, engine revs are maintained at about 1400-1200rpm during the first few minutes of engine start. As the cyclinder head warms up, the temp sensor passes this info to ICU to drop engine revs and start reducing on enriched fuel mixture. This process happens over about 5 minutes-7 minutes. Engine temp reached, revs are reduced to normal ( 550-700 rpm ). Oil is also not too thick now so Oil pressure is optimum too. ( viscosity ) EFI Engine without a thermostat : Same as above but until the optimum temperature is achieved, extra fuel is being injected and also the revs are held higher. So you will find some mechs try and reduce on engine revs but never get it right, because if you reduce the revs, the enriched mixture will stall the engine. It can take 15-20 mins to reach optimum temperature, ICU unit now restores engine to normal revs and fuel mixture. BUT, the radiator fan now comes on, cooling the engine further. This starts the the process again. Problem with cold engines : - Start up friction is high because of very small tolerances between moving parts. Oil is thicker and creates a drag. If you really want to know the dangers of lack of thermostats, try driving a turbo engine from cold start. The first thing that happens is the turbo will not kick in quickly due to thicker oil viscoity ( first 2 minutes of ) and you end up stressing the turbine shat bearings. The engine coughs before the power kicks in. Best policy with such engines is to let the engine temp build up correctly, then floor as necessary :-) my amatuer views, pls check with an auto pro..... Rgds.
Aki - you don't sound like an amatuer :) But i concur regarding the thermostat - incidentally one 'mechanic' bucked the trend and told me that it should stay in to regulate engine temperature.. -- Josiah Mugambi Charles de Gaulle<http://www.brainyquote.com/quotes/authors/c/charles_de_gaulle.html> - "The better I get to know men, the more I find myself loving dogs." On Fri, Oct 30, 2009 at 7:59 PM, aki <aki275@googlemail.com> wrote:
On Fri, Oct 30, 2009 at 6:23 PM, ndungu stephen <ndungustephen@gmail.com>wrote:
Thanks for the info guys, i definitely will ...
I thought that thermostat was put there for a reason - will opt to buy and replace it [since we think it went faulty]....
That mechanic myth i think is officially busted, ama ?
@Ndungu, I;m sharing my personal opinion so nothing to go by....
Each time I've bought a car, 2 things are changed from the time of purchase. Thermostat and timing belt. And pls do buy a thermostat from the company to maintain original parts or get it brought in. To test a thermostat, you need a thermometer and get the reading of the thermo housing eg 72, 74 deg etc. Then boil water and let it cool to about that temp. Pour into a can and place thermostat and thermometer into the can. Slowly pour hot water, until the water in the can reaches the thermostat temp. You will see the valve lift at the correct temp.
If you want to do semi-arid and desert stuff, then get a larger radiator fitted with twin fans. But a thermo would still need to be in engine.
Lets start with the efi cold engine with a thermo :
- Engine start, engine temp sensor sends a signal to ICU unit to enrich fuel. This action is similar to " pulling on the choke lever " on older engines. Sometimes, if you want better performance from an engine, you can cheat it by playing with the engine temp sensor, fooling it to think the engine is cold. The ICU unit will allow more injection of fuel.
If you notice, engine revs are maintained at about 1400-1200rpm during the first few minutes of engine start. As the cyclinder head warms up, the temp sensor passes this info to ICU to drop engine revs and start reducing on enriched fuel mixture. This process happens over about 5 minutes-7 minutes. Engine temp reached, revs are reduced to normal ( 550-700 rpm ). Oil is also not too thick now so Oil pressure is optimum too. ( viscosity )
EFI Engine without a thermostat :
Same as above but until the optimum temperature is achieved, extra fuel is being injected and also the revs are held higher. So you will find some mechs try and reduce on engine revs but never get it right, because if you reduce the revs, the enriched mixture will stall the engine. It can take 15-20 mins to reach optimum temperature, ICU unit now restores engine to normal revs and fuel mixture. BUT, the radiator fan now comes on, cooling the engine further. This starts the the process again.
Problem with cold engines :
- Start up friction is high because of very small tolerances between moving parts. Oil is thicker and creates a drag.
If you really want to know the dangers of lack of thermostats, try driving a turbo engine from cold start. The first thing that happens is the turbo will not kick in quickly due to thicker oil viscoity ( first 2 minutes of ) and you end up stressing the turbine shat bearings. The engine coughs before the power kicks in. Best policy with such engines is to let the engine temp build up correctly, then floor as necessary :-)
my amatuer views, pls check with an auto pro.....
Rgds.
_______________________________________________ Skunkworks mailing list Skunkworks@lists.my.co.ke http://lists.my.co.ke/cgi-bin/mailman/listinfo/skunkworks ------------ Skunkworks Rules http://my.co.ke/phpbb/viewtopic.php?f=24&t=94 ------------ Other services @ http://my.co.ke Other lists ------------- Announce: http://lists.my.co.ke/cgi-bin/mailman/listinfo/skunkworks-announce Science: http://lists.my.co.ke/cgi-bin/mailman/listinfo/science kazi: http://lists.my.co.ke/cgi-bin/mailman/admin/kazi/general
Ok, now the fear of thermostats has been put in me,,, can we find this particular thermostats at Piranha Mombasa road ?
participants (4)
-
aki -
Ashford Kuria -
Josiah Mugambi -
ndungu stephen