thermostat - yes or no

[jn86]

OK guys...
there's a debate about whether or not its good to take out the thermostat.

A lot of mechanically minded people and some well known forum members either promote no thermostat or are already running their cars without one to prevent overheating problems...
They say having it opened up all the time allows lower temps and that the fans sufficiently cool down the coolant as it circulates through the radiator and back into the engine...

Also, some others say that removing the thermostat will not prevent overheating...it will just delay it, but will inevitably overheat as there is not enough time for the coolant to cool down as it circulates through the radiator and back into the engine...

Post your opinions and personal experiences and or reasons.

Cheers

[Int3gra-T]

...
ever had your car with a broken thermostat?
its sucks.

[dsp26]

...
ever had your car with a broken thermostat?
its sucks.

yep!! and its coming up to winter now...

i had a seized thermostat and even with a slightly open hole my engine wouldn't warm up...


as for "Also, some others say that removing the thermostat will not prevent overheating...it will just delay it, but will inevitably overheat as there is not enough time for the coolant to cool down as it circulates through the radiator and back into the engine..."

i've read that in so many tech articles and the justification is quite sound... however on 3 different cars i've had where the thermostat seized and i had to remove it while i waited for the replacement, the engine never went to operating temp regardless how much i thrashed the cars and this was in peak summer...

[TODA AU]

I commented on this exact topic in this thread:
http://www.ozhonda.com/forum/showthr...97#post1593897

In reference to running without a thermostat.

For a track car this can be ok,
But bare in mind it can make the car a bit of a bugger to tune.
That is it won't easily maintain a steady temperature on the dyno, this tends to muck up the tune as you swing through the temp correction tables.
That said, if the temp correctings are bang on, you're laughing.
(But to start with, generally they're not... So that can mean more work)

Further to above,
If you do decide to run without the themostat,
You aught to block off the bypass from the head to the inlet of the pump on the thermostat housing.
The base of the std thermostat blocks this when open.
When the thermostat is removed, the bypass remains open & is effectivly just a radiator bypass which can potentially cause cooling issues.
(Welding the head & housing is probably the most effective way to acheive this if you've set on running no thermostat)
Also, try & keep the factory water oil heat exchanger, as it will help warm the engine up.

For proper flow, you may need to fit a restrictor / orifice of the same size as an open thermostat to aid in flow control.

All of the above said,
We generally tune with thermostat in place & fit a cooler one after the tune if required for track use.
But generally always run with a thermostat.
Talk to your tuner about this, He may want a thermostat in for the tune.

Hope that helps...

So, my opinion is to run with a thermostat.
If you have a cooling issue, it is likley related to the radiator,
Lack of an oil cooler or some other deficiency or issue.
A thermosat is not an expensive thing & it keeps the engine up to temp.
Running too cold can be as bad or worse than running too hot.
Cheers

Adrian

[Nath]

im sure you all know this, but a thermos stat is there for a damn good reason.

obviously staying shut while hte engine is cold, so that it warms to operating temperature quickly. engines are designed to run at a certain temperature. when they are bellow (or above) this, they do not run as efficiently as when that are at oper. temp. They use more fuel, change ignition timing, and everyone knows a cold block can get worn cylinders alot easier.

there for when the thermostat is removed, the radiator is constantly removing heat form the coolant. taking LONGER to heat up the engine.

i would strongly recomend NOT removing yours. they are there for a damn good reason. if they were more harm then good after 30 years, manufacturers would have removed them

[Nath]

adding cold water to ANY hot engine will damage it. whether yo uhave a thermostat or not. cos when the engine is at operating twmp. (HOT) the thermo is open to allow flow to teh radiator to cool it down

never add cool water to ANY hot engine. allow ATLEAST 20mins for it to cool down with the bonnet open.and obviously never open a radiator cap when hot.

water/coolant boils at a MUCH higher temp when under pressure (by a rad. cap) when yo usuddenyl remove that pressure, the fluid is suddenyl taken to atmo. pressure and RAPIDLy turns to steam which as we know, expand QUICKLY. lol i have seen this several times first hand.... not pretty

[JohnL]

i've read that in so many tech articles and the justification is quite sound... however on 3 different cars i've had where the thermostat seized and i had to remove it while i waited for the replacement, the engine never went to operating temp regardless how much i thrashed the cars and this was in peak summer...

Keep in mind that a cooling system in good nick has a lot of reserve capacity, so despite being thrashed on a hot day your cooling system had no trouble keeping the engine below 'normal' with no thermostat installed, even if this did cause the coolant to flow too quickly and thus reduce the efficiency of the system.

If however the cooling system had been more marginal, then (all else being equal) the increase in flow rate caused by deleting the thermostat might have been enough to cause the engine to run hotter than might otherwise have been the case with a thermostat fitted and a slower coolant flow...

I'd never run without a thermostat, there's just no point. Years ago I had a car fitted with a very modified Austin-Healy Sprite engine (about 100hp, a fair bit of power in a car that only weighed 500kg!), and I ran that motor with no thermostat for a while. However, it didn't take long before I fitted one, it worried me that the temp stayed so low most of the time, and it also affected drivability.

Note that when I didn't have the thermostat fitted that I didn't just delete it, I replaced it with a special blanking sleeve (sourced from the BMC 'Competition Department' would you believe!). This sleeve was expressly designed to slow the rate of coolant flow through the cooling system on racing engines where the thermostat had been deleted, though I still can't see any good reason to not use a thermostat, even on racing engines...