Operation and purpose of the calorist / thermostat

The element that unites the cooling circuit, the calorostat, is a kind of "switch" that directs water along one path or another. Let's find out how it can be used ...

System purpose

The purpose of the calorstat is to be able to direct water into a small or large cooling circuit, depending on current needs. Indeed, the engine performs much better (on all levels) when it is warm. So when the car is cold (and especially the coolant) it's not necessary (or even annoying) for the cooling system to run at full speed, it will delay engine warm-up too much!

To shorten the heating time, the cooling circuit is deliberately shortened and water does not pass through the radiator. In this way, the calorostat prevents water from entering the radiator in order to return it to the engine as quickly as possible, a kind of shortcut / bypass that accelerates the heating of the water. See diagram below.

The engine is cold, only the small circuit is running

As soon as the water reaches the temperature quickly, it should not rise higher: the thermostat directs the water into a large circuit (on which the radiator stands).

The work of the colorist

How can this little element know that it should (or shouldn't) be passing water through the large circuit when it gets hot? Well, this element is made of wax, which reacts quite strongly to heat. Indeed, the latter expands, especially when hot, allowing the opening mechanism to be activated.

In summary, when the water is hot, the wax expands, which triggers the bypass mechanisms in the larger circuit. By the same logic, the wax is drawn in during cooling, which closes this bypass towards the large circuit.

Calorstat / thermostat malfunction?

Once you understand how this works, it is quite easy to deduce the problems that may arise. Thus, two cases should be expected

• Thermostat stuck closed : even hot water does not cool down to the radiator. In this case, the engine will quickly overheat due to the high pressure in the cooling system.
• Calorstat locked in open position : the car heats up much longer, which is not very good for the mechanics. Indeed, you know that the engine wears out faster when the engine is cold, and indeed, it stays cold there longer. So, let me conclude ...
• flight at the calorstat level: you lose water, which jeopardizes the engine if there is not enough water to cool the engine

Your support

Below are the latest feedback on the site's testlists:

Porsche Cayenne (2002-2010)

4.8 385 HP 300000 km'2008, discs 20; Cayenne s 385ch : At 300km spark plug starter sensor Pmh steering hose assists water pump caloristat

Skoda Octavia 2004-2012

2.0 TDI 140 ch 225000 km bm6 elegance : exhaust gas cooling, throttle valve.thermostat the block is open.

Ford Focus 2 (2004-2010)

1.6 TDCI 110 HP Manual transmission, 120000 - 180000 km, 2005 : Excessive oil consumption Wastegate (turbo) Starter Front and rear electrical harnessescaloristat Suspension triangle (wear) Exhaust gas recirculation valve

BMW 3 Series Coupe (2006-2013)

320i 170 kan 162000 : To begin with, I’ll tell you about what I had or had as a malfunction on a run of 157 km - engine mounts (the car vibrated above 000) - shock absorbers, silent blocks and rear cups are pierced with rust, the shock absorber crosses the trunk - exhaust braids - lambda probe after the catalyst - front and rear brake hoses, rear pipes and left rear caliper - oxidized cradles, which I ran through a rust converter and repainted (snowy road due to the fact that it comes from Belgium) - trunk lock -driver's belt-entrance -radio pixel erased at the bottom - a reminder of the ventilation of the BMW Changed the former owner

-injector-coil-thermostat-lambda-sensors -seat preparation And this is as far as I know and those that I mean.

Dacia Logan (2005-2012)

1.5 dCi 85 ch MCV 7 seats Laureate, 300000 km, 2009 : - central locking motors for driver and trunk, failed at 300000 km and 11 years (10 for 2) - steering wheel wear I sewed a leather steering wheel cover that looks good for 20.

Mercedes A-Class (2012-2017)

250 ch 211g auto 7 km urban (germany) : Frame thermostatic controls the coolant. Orange light.

BMW Series 5 (2003-2010)

525d 197 HP Automatic transmission, 240 km, 000 y., Premier finish : Bva reverse gear first gear second and third skid verdict bva hs gear shift fortunately found used cheap thermostat

Peugeot 308 (2007-2013)

1.6 VTi 120 HP premium version, 150 km, aluminum rim : the engine is generally unreliable lambda probe, caloristat then misfires = damaged valve

Volkswagen New Beetle (1998-2011)

1.9 TDi 100 HP 220-speed manual transmission, Year 000, cara cabriolet trim : there would be egr, thermostat, radiator, rear window cable (convertible), which produces very modern, see normal for newbeetle convertible, rear door lock, glove box handle fart 0_o (note after purchase -_-). It's not serious if you are a little handyman (poor like me hahaha) doing well.

Fiat 500 (2007)

1.2 Meca gearbox 69 hp, convertible, white, drives in the south of France : thermostat coolant

Mercedes E-class (2002-2008)

270 CDI 177 channels : thermostat

Mercedes C-class (2000-2007)

220 CDI 150 channels : thermostat remains locked open Turbo crash

BMW Series 3 (1998-2005)

330i 230 chassis 330 xi Touring 2004 BVM6 145 km : Annoying topic... Without going so far as to say that the car is not at all reliable, it is still subject to a lot of failures that are not very tolerable given the price and reputation... which, as for many Germans, is very overpriced. A few immobilizing breakdowns, but a lot of details, some of which can have serious consequences, but the number of which, nevertheless, spoils the party a little. The car is more complex than the others, with thinner systems in some areas, but it comes at the expense of all those minor damages. So in bulk - Fragile cooling system. Moreover, the engine is clearly very hot, given the displacement, and that on an engine with a long block, for example, inline with 6 cylinders, it is easier to achieve catastrophic deformation. The expansion tank is cracking, the water pump often fails sooner than you expect, caloristat also fragile. We can solve the problem by taking preventive measures. Luckily, it's not very expensive and fairly easy to make. To believe that it is conceived from the very beginning - Different and varied hinges to change. Rocker Cover Gaskets, Power Steering Chain Gaskets, DISA Valve Seal – The front suspension inevitably shows weak signs. Front axle silent blocks, transverse levers, cardan bellows (on C, obviously not on the others) - damper pulley. This is something that also changes regularly on other cars - the HS oil level sensor. Moreover, a breakdown when the engine constructively consumes oil - Oil consumption from 0.5 to 1 liter per 1000 km. This is inherent in the M54 engines. It's not abnormal, it's just a bit of a pain and a bit of a myth dispelling - Oil Vapor Recovery System. The parts aren't expensive, but they're tricky to take apart, and overall it doesn't work very well. Some people replace this with a "trap" - a DISA valve that can end up throwing debris into the intake with imaginable consequences - headlight washers that won't come out anymore - a few very subtle movements when starting from 1st. Only occasionally, probably related to the transfer case of 4WD versions. – The flywheel is notoriously weak, like a lot of dual-mass flywheels. Fortunately, I have a rather progressive malfunction - VANOS, which can easily fail. Mine has been spared for now - Coils change frequently (well, it happens on many other models too) - Exhaust screw that very often ends up flaking and rusting. The result is a rattling noise when lifting the foot at 1500-2000 rpm. Repair costs nothing, on the other hand, troubleshooting is painful - one or more HP is disabled. A known problem… personally in BMW I have never seen this anywhere – scratches on the handbrake and gear lever. You can live with this, but this is a task in the interior, which greatly contributes to the interest of the model. New parts at an obscene price (+ - 150¤ each) is a lot for a car with the reputation of Deutsche Qualitat. It's too much, much more than what I've seen on other models, 406 V6s, 106s and even... AX (but there's nothing in the AX D). On these vehicles, maintenance was limited to batteries, shock absorber pulley and routine maintenance. Less refined, prone to gray tones, but really reliable. Actually, there is a price in all this, but also and especially the time spent looking for a breakdown that can end up ruining the fun, because we are always waiting for the next one in fear. big ticket to put it on the counter. However, the car has only 145 km, and I have had it for 000 years and 10 km. Should be taken into account.

DS DS3 (2009-2018)

1.6 THP 156 HP BM6, 96000 km, sporty chic 2013, Citroen Racing brakes : BSE box ( caloristat H / S at 90000 km 96) Leakage in the water pump at 000 km.

Renault Clio 4 (2012-2019)

0.9 TCE 90 ch manual transmission, 71 km, 000 g. : Leakage of coolant from the housing caloristat, which leads to problems with the cylinder head gasket and contamination of the oil with coolant. A circuit that needs to be redone completely.

Peugeot 208 (2012-2019)

1.6 THP 200 channels : Water pump leak - 50000km Power window motor - 80000km Defective 3rd brake light - 82000km Low pressure pump - 85000km Box caloristat – 90000km Ignition coils – 90000km

BMW Series 3 (1998-2005)

330d 204 HP Automatic transmission 330Xd (all-wheel drive) 4km year 250000 : Inside - 16/9 gps screen that gets old a lot, in fact it's not uncommon to find these screens with pixels that don't work anymore… - Average quality leather driver's seat worn on the blank as well as a ripped steering wheel. – The famous BM54 amplifier that burns regularly. Symptoms: a hissing sound when the sound is no longer heard and poor radio reception. Quite an expensive part in a new one, but fortunately there are other solutions if it is repaired. Let's get outside pretty good overall - the grille is loose, you have to go through the grille in the grille to fully open the hood. with a grate in hand? – headlights that dim due to the use of plexiglass, but a problem that is not inherent in this car. - front/rear emblem that comes off over time - Windshield plastic strip that cracks replaced under warranty.thermostat The EGR valve was replaced, the coolant escaping from the engine, the water jet ... I got the impression that I was walking along the shores of Lake Geneva in Geneva ... -Various problems with the HS transfer case, combing to ...

Citroën C3 (2002-2009)

1.4 75 ch Furio Essence 106 km / sec 000 : caloristat (thermostat water) HS - cylinder head gasket at 100 km, from which a little oil flows out on the distribution side (not too seriously, all TU engines do this, if it does not leak too much, no need to change) - 000 km remainder, only classic maintenance, emptying, filters...

BMW Series 3 (2005-2011)

325i 218 hp Manual transmission, 102000 km, 2006 325 xi, flexfuel conversion : Water pump + thermostat (102200) + ignition coils

Citroen C3 Picasso (2009-2017)

1.4 VTi 95 ch May 2011 110000km comfort : Unintentional start of the rear window washer The fuse for the interior heating fan must be replaced (once) The water block thermostat changed (not under warranty) incompetent Citroen in the garage, the problem was known and it was not changed. So breakdown (does not start). The gearbox is a bit tricky to maneuver. (do not leave in gear with the engine off).