Thermostat Is It Really Needed

[Guest big kev]

Been doing some basic mok ups for plumbing the rad to the dohc.

 

Got me thinking.

 

Why can't I just do away with the thermostat and fit a switch on the dash for the fan. Simple get in start engine when it's warn turn the fan on .

 

Was thinking it would save some plumbing wiring and bring the budget down. some plus another nice switch on the dash board

 

Thoughts please

 

Cheers

[Guest NantLladron]

I put a manual fan switch on my essex V6 powered land rover ........yep one day forgot to switch it on ............talking .........talking ......steam !! head gasket

[Longboarder]

Can you think of any cars that don't have one? It's a very simple device that controls the running temperature of the engine 99% of the time all by itself and without any action from the driver or electronic boxes and it's very reliable. Only needs fan assist under in stressing situations like jams on hot summers days. To save cash try to use the ford one that comes free with your engine. Use a rail as a second choice only. Whatever you use must have a stat in it.

 

Nigel

[Guest paulrrh2b]

Yep,

 

Definitely keep the stat., otherwise you will encounter a whole host of issues, not to mention the risk of a knackered engine. If cost is an issue, try local breakers yards and the like, then upgrade later on.

 

Paul

[Guest paulrrh2b]

 

Yep,

 

Definitely keep the stat., otherwise you will encounter a whole host of issues, not to mention the risk of a knackered engine. If cost is an issue, try local breakers yards and the like, then upgrade later on.

 

Paul

 

[BigLee]

I have run for last 5 years without one - just to stir thing sup a bit... Car needs cooling as gets very hot under bonnet so i left it out - It gets warm v quick anyway ...

[Longboarder]

But you have a cooling problem Lee. Too little rad capacity, rad size, rad airflow ducting, exit points for air from under-bonnet or whatever. Removing the stat removes a slight flow restriction and will get you a little more flow through the rad. Very marginal extra cooling and slower warm up. Just enough I guess to help you. As a general principle 999 cars out of 1000 will run better, more economicaly, lower emissions and with less engine wear with the correct stat. Yours just needs sorting! You can't get away with it on a modern engine like a zetec or duratec.

 

Nigel

[ibrooks]

People get confused between what the stat does and what a thermostatic switch for a fan does. Understand what they do and you can make your own informed decision.

 

Number one concept. Obviously there is a maximum temperaure for the coolant in an engine above which damage will occur. There is also a minimum temperature. Engines runnng cold don't tend to suffer sudden and dramatic failures but they will have a reduced life and they will not run as efficiently and make as much power as they might.

 

The cooling system needs enough capacity to take the excess heat out of the engine under the worst conditions - whether that means when it's running at full chat around a circuit or sat in a queue of traffic (likely on a hot day in both cases).

 

Adding airflow to the system increases that capacity. That's why some cars are perfectly happy when moving along but bubble up in traffic - not enough airflow. Hence fans.

 

This means that the cooling system has too much capacity for most of the time and is robbing heat that should really be left in the engine. That's why we want fans that can be switched off (or slowed) when the engine is cold. Electronic switches are used on leccy fans or thermo-viscous couplings can be used on mechanical ones (like the original on the Pinto in a Sierra).

 

OK so we've switched the fan off but when driving along we still have airflow through the rad so it's still sucking heat out of the engine. How do we stop that? Basically we reduce the flow of coolant through the radiator and that's what the thermostat does. As the temp goes down the valve closes and the flow through the radiator drops. As the temp goes back up the valve opens again and flow through the radiator goes back up.

 

BigLee - if your car runs at a proper temp without a stat and also doesn't overheat you're very lucky.

 

Iain

[BigLee]

Yes I agree with all but my philosophy is if it aint broke I appreciate the marginal extra flow through the lump to try and keep it cool. But if you are planing with new engine etc. leave it it and ensure rad is suited to cooling it.

[Guest chris brown]

Yes fit a stat but don't rely on a manual switch for your fan - very embarrassing to turn up at a meet or show with water and stem emitting from under the bonnet. I know I did at Stafford some years back and it took a long time to live it down

[speedtripledan]

My v8 has no stat and runs approx 85 - 90deg i have an electronic fan switch set for 95deg and to be safe i have a manual override switch as i had a fan switch fail once.

[Dave R]

Yes fit a stat but don't rely on a manual switch for your fan - very embarrassing to turn up at a meet or show with water and stem emitting from under the bonnet. I know I did at Stafford some years back and it took a long time to live it down

 

who says you have yet????