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cavedweller

Running with no thermostat

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cavedweller

I'm currently running my engine without a thermostat. This doesn't seem to bother the car in any way but I was just wondering if there's anything I should know.

 

Basically the car seemed to randomly get hot a few times for no reason and I suspected a sticking thermostat. The fan works fine and comes on when it should. It's a 1.0 engine with around 50000 miles and most of it looks like it's hardly ever been changed or tampered with so I took the thermostat out and replaced the small amount of lost coolant with a substance called "water" that seems to do the trick, and I have been running it like that for a couple of months without any problems. And yes I will probably fix it properly at some point but for now the car seems quite happy and It's not winter so I'm in no need of a strong heater at the moment.

 

The temperature reads at the lowest end of the guage most of the time and only ever creeps up to almost normal if the car is stuck for ages in heavy traffic on a hot day but even then the temperature still doesn't seem to get high enough to even trigger the fan so I've not been too concerned. However, if the car was still like this at MOT time would the cooler running temperature possibly cause a fail on emissions or does the ECU still sort that out even at low running temperature?

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dvderlm

Should be fine. MOT test prescribes minimal oil temp of 60 degrees C.

https://www.mot-testing.service.gov.uk/documents/manuals/class3457/Section-8-Nuisance.html#section_8.2

 

Just water for coolant - especially tap water not de-mineralised - will allow block to begin to corrode.

But a small amount added to antifreeze will be okay.

 

 

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steveo3002

i think it should pass okay unless its really cold weather and the car wont be up to  temp 

 

however you will running around alot with the engine too cold , long warm up etc , probably wasting more fuel than the cost of a stat , id also suggest when you do buy one make sure its top quality ,ive has issues with the rubbish ecp sells

 

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caretakerplus

I would recommend a 50% coolant 50% water mix for the cooling system. This not only provides frost protection, but more importantly at this time of year when there isn't any frost, it prevents corrosion.

As said above, plain water is never a good idea, especially where aluminium parts are involved, as these are the first to suffer from corrosion.

 

Running the engine without a thermostat, should be thought of as a 'first aid' procedure only.

Cold running not only produces  acidic sludge to form in the engine, but the working clearances are affected also - obviously, metal expands when heated, so running the engine at (say) 30°C rather than 90° can make a big difference.  You will almost certainly be using too much fuel as well.

 

Regards

 

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dvderlm
13 hours ago, steveo3002 said:

i think it should pass okay unless its really cold weather and the car wont be up to  temp 

Nah, tester's manual says hold engine at 2000 to 3000rpm until oil temp is 60C.

Exhaust manifold is easily 300C. Bonnet down, no airflow will probably take under 10 minutes -

less if it arrived warm. It would need to be freezing in the test bay. Coolant might not reach 60C but oil will

with probe down dipstick or on the filter.

 

And if they can't get it to temp a sensible garage will replace the stat and charge for 

diagnosis time, draining, flushing, refilling. bleeding, stat, o-ring, coolant,  environmental disposal of the old coolant, labour at ££ after first informing the customer

of the estimated bill including VAT. A bad or unscrupulous garage may also want to fit a new radiator and water pump, hose-clips and not be able to source the correct

stat for a week.

 

 

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cavedweller
On 17/05/2019 at 22:23, dvderlm said:

 

And if they can't get it to temp a sensible garage will replace the stat and charge for 

diagnosis time, draining, flushing, refilling. bleeding, stat, o-ring, coolant,  environmental disposal of the old coolant, labour at ££ after first informing the customer

of the estimated bill including VAT. A bad or unscrupulous garage may also want to fit a new radiator and water pump, hose-clips and not be able to source the correct

stat for a week.

 

 

Some things never change. Sounds just like the sort of friendly honest service you could expect from any garage in the 1970's.

 

I do intend to replace the thermostat at some point before the next MOT, actually the whole plastic housing thing as the screws snapped off when I tried to remove the old thermostat and I've just temporarily bodged it back together but it's holding up just fine for now. I've already got a new housing and I'll probably do the main hoses as well when I finally get round to it. Only had to replace a couple of liters of coolant with water so I think that'll be fine for now.

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nige8021

Those self tapping screws for the cover of the thermostat are such a crap idea, at best you've got two removal/refits before there is nothing for the screws to bite into, I was going to drill the hole out and fit a rivnut, but after two complete housing failures (ECP pattern parts) the engine cooked itself and was only fit for the scrappy 

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