Thermostat in or out?

[axe]

Hey gang,

I dropped my car in the garage to finally resolve the idling problem and so far so good, it is smooth as a sleeping cat... however when getting warm, the engine will tend to choke and stall if left too long without giving it a bif of "POWER" (Jeremy Clarckson fav word)...

Anyway, the dude in the garage knows the Ford V6 engines (or so he says) and he told me that removing the thermostat will allow the car to run a lot cooler than it does. The temperature on mine will reach the last white bar on the gauge but never goes over it, stays about 1 to 2 mm under (which I think is right).
So what you all think? is he talking BS or anyone done it already?

aXe

[apple]

If you remove the thermostat then there is nothing stoping the coolant from passing through the system into the expansion bottle and then on to the road! Its there to maintain system pressure and to help the engine warm up during the winter.

apple

[tvrgit]

Eh????

This bit is right:

apple said:

Its there ... to help the engine warm up during the winter.

Not so sure about the rest - the thermostat does not seal the system nor does it help maintain system pressure.

[axe]

I knew about the heater and in summer, no need for it...
But I am a bit like the dude above re the coolant dripping on the road

aXe

[GreenV8S]

The thermostat has got nothing to do with controlling the pressure. It just determines whether the water pumped out of the engine goes through the radiator or the bypass. You should definitely retain the thermostat, without one fitted the engine will take longer to warm up and will suffer from overcooling in most conditions. In the situation where overheating occurs, the thermostat should be fully open anyway.

The stat does provide a small restriction even when it is nominally fully open, and if the cooling system is very marginal the extra flow from removing it may be the difference between finishing the race, and not. But this is not a situation you should be in with a road car.

[honourablepickle]

seems obvious but make sure the stat has the right opening range and that it works
reb

[tvrgit]

axe said:

...however when getting warm, the engine will tend to choke and stall if left too long without giving it a bif of "POWER"

When you say "when getting warm" do you mean

(a) "while it's warming up from cold" or

(b) "when it's been idling for ages and starts to get a bit hotter"?

If (a) then it's nothing to do with the thermostat - in fact removing the thermostat will make it take longer to warm up so the problem will be worse. It's more likely to be an engine temperature sensor (not the same one as used by the gauge - the one used by the ecu) or something in the fuel management system - Idle speed control valve, fuel enrichment, something like that.

If (b) then, if the engine is already hot, removing the thermostat will not make it run cooler if the car is standing still - well it might, but the difference would be marginal and not noticeable enough to make a difference to that kind of problem. Again, more likely to be a fuelling problem (such as plugs fouling slightly due to over-rich idle mixture or even slightly more oil being drawn past the piston rings under the high engine vacuums at idle.

It could be something as simple as spark plug gaps... very hard to say.

You need to have it looked at by somebody with both a fault code reader (which should identify if any sensors are "out of range" ) and a fair idea of what they are doing.

Edited by tvrgit on Friday 28th July 16:53

[ijbd]

At idle the thermostat has no control over temperature. Because there s no airflow through the radiator.
Thats what the otterswitch/fan is for, necessarily at a higer temperaure.
Only when driving, say 60 km/h in summer, the fan switches off, and the thermostat controls again.
If your idle temperature is limited by a running fan, your system seems to work correctly.

If your fan is not switching on, you need to check, because you might have trouble if the weather becomes hotter.
The temps are in the bible, I think 82 C for the beginning thermostat opening (below 90 C on my gauge) and 90 C for the otterswitch, might be your 2 mm before a white line, and long before red on my gauge.
If you are worried, you can check the opening/switch temps by removing them from the car and immersing them in a pan of water on the stove.
If you do not a thermometer, 80 C is when the first (air) bubbles come out. Boiling is 100 C.

mvg Boudewijn

[ijbd]

Oh, and never take the thermostat out only.
In most cars that means the waterpump flow gets splitted to radiator AND bypass.
A wide open thermostat shuts off the bypass, and directs the flow to rad only.
There are special blanks for this (a cylinder covering the bypass hole), but you do not need that.

mvg Boudewijn

[axe]

Thanks for you input all of you
The thermostat out was an idea of the dude that dide tune the car. He put the mixture to 2% (was set to 4%) and told me the sparks need to be changed for better quality ones. Dunno which one I could put, any advice here?

I still have the same old problem about the car choking slowly to a stall but that had nothing to do with removing the thermostat, sorry if I explained myself in a twist
When I take the car from home to work or work to home, arriving at destination (max 5 miles), the engine has reached his below 90 deg temperature and if I push a little bit the gears, I would notice a choking effect when stopped at a red light... I know it doesn't make much sense... It is better to see and hear the car than trying to describe with words...
Actually, I might make a video tomorrow to show you what the pb is...
And maybe you can also explain to me why it takes so long to start when engine is hot... Have to keep the key turned for a while before it springs to life.

aXe

[Le TVR]

From the symptoms I would start with the airflow meter.
They do tend to slowly get stiffer from dirt and dust.

Spray some WD40 on the airflow plate hinge bearing, clean the plate and recentre it.

What happens is that as you give it a bit of 'stick' the plate no longer drops back to the same position. As the plate is underdamped it can drop lower than it should for idle and stick there under you give it a bit of gas.