Why DO people remove/keep thermostats open?

[bull996]

Chap at work just changed his thermostat as it was running a bit cool. When he took the old one out, someone had removed the stat bit, so it was permanently open, hence the cool running.

Now I have heard that people do this when they overheating issues, but I JUST cant work out why!

The stat is closed when cold, so that the water dosent circulate in the radiator so it warms up fast.

When warm, the stat opens, sending water rond the radiator, keeping it cool.

Now, if someones car is overheating, then why remove/force the stat to stay open, when it would be open anyway (as the car running too hot)?

FWIW, he drove the car for 20 mins and left it idling for 20 mins and temp gauge stayed bang on half.

Am I being thick? (Not unusual)

[Stu R]

It's an easy way to see if the stat's the problem. If it is and they remove / 'adjust' it, water circulates as normal and no overheating. I guess if it cures the problem, swapping it out for a working one will be placed firmly towards the bottom of the 'important stuff to do' list and get forgotten about.

They can be fickle little things too of course.

[Cotty]

bull996 said:

Now, if someones car is overheating, then why remove/force the stat to stay open, when it would be open anyway (as the car running too hot)?

Mine jammed in the closed position so overheated, if it had jammed in the open position I probably would not have noticed.

[bull996]

Cotty said:

Mine jammed in the closed position so overheated, if it had jammed in the open position I probably would not have noticed.

Yep, I understand that-makes sense.

But I dont understand why you want it permanently open.

[Mr2Mike]

People often seem to think a thermostat is a undesirable restriction to coolant flow and that removing will magically cure overheating problems, without understanding the implications.

[Dab of oppo]

Seems on the pointless side to me, as already said its not a magic cure, it just takes the already faulty car longer to warm up.
I change mine along with the water pump when I change the cam belt and tensioners on my vehicles - so cheap, but soooo much trouble if they go wrong!

[bull996]

Dab of oppo said:

Seems on the pointless side to me, as already said its not a magic cure, it just takes the already faulty car longer to warm up.
I change mine along with the water pump when I change the cam belt and tensioners on my vehicles - so cheap, but soooo much trouble if they go wrong!

Thats the way I think. However, there doesnt seem to be problem now its repplaced, so why do it in the first please?

(Unless there was other problems that have been fixed AFTER trying the stat?)

[Mr2Mike]

Dab of oppo said:

Seems on the pointless side to me, as already said its not a magic cure, it just takes the already faulty car longer to warm up.

They likely will never warm up properly without a thermostat, especially in cooler weather. Without a 'stat, the coolant temperature is effectively controlled by ambient air temperature.

[redstu]

If the coolant stays cooler then the pressure will also be lower, this can hide fluid leaks when it comes time to sell.

[Fish981]

They're normally the same people who think a piece of cardboard in front of the radiator will make the car warm up faster.

[mcford]

I think that on the E series engine as used in the Maxi and Allegro, that removing the thermostat interfered with the coolant flow to such an extent that there would be no coolant flow around one of the cylinders, leading to the demise of the engine.

[Tunku]

Won't a colder engine run richer, meaning a bit more power? Assuming the missing thermostat fools the ECU?

[Ozzie Osmond]

They are, quite simply, idiots. Fiddling about with thermostats shows a lack of understanding of the basics.

[crolandc]

This used to be the thing to do in ages past when the engine was about goosed ( using oil and breathing heavy ) it keeps engine cool and can give you a good few thousand more miles before scrap yard beckons.

[HedgehogFromHell]

Tunku said:

Won't a colder engine run richer, meaning a bit more power? Assuming the missing thermostat fools the ECU?

I thought it was run lean to get more power but with greater risk? Saying that it's been a hard day running up rivers... So I could be wrong.

[wolf1]

Or the engine was overheating due to a stuck thermostat and was temporarily removed/opened by a breakdown mechanic so they could get home or to the garage and they never bothered to get it fixed properly.

[Dracoro]

Tunku said:

Won't a colder engine run richer, meaning a bit more power? Assuming the missing thermostat fools the ECU?

Colder AIR improves performance (air density), not colder engines. That's what I remember anyway

[Alfanatic]

Because the removed one failed in the closed position, causing the overheating. Way back in the days of carbs and points and dizzies it was common to remove the thermostat and not bother to replace it, because it was one less thing to go wrong and an overheated engine is very bad but noone cared about an engine running too cold.

EDIT: Oh, as for testing one, stick it in a pot of water, then bring the water up to the boil on the hob and see if it opens.

Edited by Alfanatic on Tuesday 4th October 19:01

[redstu]

Tunku said:

Won't a colder engine run richer, meaning a bit more power? Assuming the missing thermostat fools the ECU?

It will use more fuel as it will take longer to get to operating temp, if it manages it at all. But not give more power as it won't be burning it efficiently.