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.