tyc

Upgrade thermostat

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Termostatul OE de la Smart CDI este proiectat inadecvat, doar OE-urile sunt perfect funcționale.
Acesta este motivul principal care ma determinat să înlocuiesc termostatul (ca sistem) cu cel din carcasa metalică. Încercările anterioare de a adapta un element de ceară de etanșare din cauciuc au avut un efect limitat - și în versiunile DIY și AM.
Prin urmare, vreau sa schimb tot corpul termostatic, alegerea a fost totul, de la aluminiu si element de ceara cu garnitura din cauciuc.
Cel mai apropiat element este motorul WV T5 / 2.5TDI, Topran 112244.
Corpul viitorului termostat este fabricat din mai multe bucăți de aluminiu care necesită multe ore de frezare. Diametrul tăvii principale a elementului de ceară este de 40 mm. Diametrul suportului arcului este de 52 mm.
Anvelopa principală este cu garnitură de cauciuc fără supapă.
Opiniile despre lucrarea prezentă?

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Edited by tyc

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From Above;

"OE thermostat from Smart CDI is inadequately designed, only OEs are perfectly functional.
This is the main reason that has prompted me to replace the thermostat (as a system) with that of the metal casing. Previous attempts to adapt a rubber sealing wax element have had a limited effect - in both DIY and AM versions.
Therefore, I want to change the entire thermostatic body, the choice was everything, from aluminum and wax element with rubber gasket. The closest element is the WV T5 / 2.5TDI engine, Topran 112244.
The body of the future thermostat is made of several pieces of aluminum that require many hours of milling. The diameter of the main tray of the wax element is 40 mm. The diameter of the spring support is 52 mm.
The main tire is with rubber gasket without valve. Opinions about the present work?"

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Impressive work and workmanship there tyc. Obviously man will shift mountains to stay warm. 

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OEM Thermostat from Smart CDI is inadequately designed, only OEs are perfectly functional.
This is the main reason that has prompted me to replace the thermostat (as a system) with that of the metal casing. Previous attempts to adapt a rubber sealing wax element have had a limited effect - in both DIY and AM versions.
Therefore, I want to change the entire thermostatic body, the choice was everything, from aluminum and wax element with rubber gasket.
The closest element is the WV T5 / 2.5TDI engine, Topran 112244.
The body of the future thermostat is made of several pieces of aluminum that require many hours of milling. The diameter of the main tray of the wax element is 40 mm. The diameter of the spring support is 52 mm.
The main tire is with rubber gasket without valve.
Opinions about the present work?

 

English translation is not the best, sorry. I hope, however, to understand the idea I want to convey.

You're right. I'm intolerant to cold - probably from a motorcycle.
I think if the engine works properly and the temperature is the right one. In the sense of optimization, I want to do something simple on the diesel cooler ...

We did the leak test and the result was 0.00ml leakage.
Test liquid - water, laboratory - washbasin. I filled the elbow and for 5 minutes I recorded 0.00ml leakage, the tissue paper was not moistened.
So far everything is fine, but what can I expect?
This thermostat opens faster (87C vs. 90C OE Smart) and more brutal (1257mm2 vs 177mm2 OE Smart, in section).
The engine for which the Topran was designed is a 2.5 liter but knows a 1590mm2 thermostat made for a 1.9 liter engine ...

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I must just be lucky with this car, but 136,000 km in the Canada 1 and the original thermostat still functions perfectly.  Holds 82-85 C all the time, even down long hills.

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So you really lucky.
At me, the temperature did not pass 2 bullets @ 134,000km. I changed the thermostat to a new one but ran only 30,000km.
Now the car runs with the empty thermostat housing but gets very hard at 80C (in 25km).

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Today I made a key for fixing the thermostat housing.
I also fit the thermostat.
The role of the bypass circuit in the cooling circuit is to protect the engine
 in the event of the heating matrix clogging - until the thermostat opens.
This also leads to difficult heating in cold weather.
Tolsen solved the problem by restricting the bypass flow. Restriction leads to valve closure.
My thermostat has no valve (I can see how the air blows out!) And the efficiency of the Tolsen restrictor is limited. I am thinking of a presostatic controlled solenoid valve - if the pressure in the circuit increases to a certain preset value then the solenoid valve opens. The same situation and if the temperature reaches 100C - anyway, do not want cracked hoses. Installing the solenoid valve and the electronic control circuit will be stage 2 and will only occur if the results are poor.
For the time being, I will only handle the thermostat - I hope the next winter is true. I'm looking for material for the new bottom of the wax element

1-DSCF6725.JPG

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The place where the plug is mounted on the wax element through the thread (M8x1.25) .

1-DSCF6727.JPG

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I wonder is there is suficient room for your big  thermostat to fit.

 

My Cdi is currently running with an old not particularly good original Wahle thermostat and takes a long time to warm up.  I might therefore fix my poor Gates that came apart last winter leaving my wife stranded in the cold with a steamed up Smart and no heat. I came to her rescue riding my 1998 Yamaha 50 cc BWS scooter driving through snow and sleat.  A very cold and miserable experience. I nearly froze my balls off.

 

MotoRad2.jpg~original.jpeg

The weakness is the threads holding the two housing pieces toghether so I intend to add some sort of external metal C clamp around.

 

A few more photos to benefit those that have not seen this type of thermostat:

MotoRad3.jpg

 

MotoRad4.jpg

Above disc is home made from marine bronze.  Has O ring seal which fits snugly into the groove.

 

MotoRad6.jpg~original.jpeg

Wax element is original Gates.

 

Bleeding air out requires a special procedure since this modified Gates does no longer have the infamous check valve in the disc.  I simply vacuum bleed.

 

The only purpose of the check valve is to allow air to escape to temperature sensor when bleeding cooling system.  Without a check valve and disc fully sealing against its seat, the air contained in coolant flow pipe to radiator cannot be bled out the normal way.

of course there are many ways to skin a cat.  One can fill up coolant to the highest point on cylinder head before fitting termostat.  Vacuum bleed is still my prefered method.  Quick and easy.  Got a very good China vacuum bleed kit on Ebay.  Cheap as chips.

 

The orientation of the check valve is main reason why we have trouble getting our wee engines up to operating temperature.  Traditionally, the wax element in thermostats were sitting with disc orientation horizontally and check valve sitting verically in its hole in disc.  Just a tiny pressure differential was sufficient for check valve to seal.  On our Smart engine the disc is orientated in the vertical plane.  Check valve then drops to the side of its hole and won't seal thereby valuable heat is constantly lost and engine struggles to warm up.

ThermostatDiscReduced.jpg

Disc and check valve from an original Wahler thermostat.

 

 

 

 

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Vacuum bleed kit in action:

DSC03450.jpg

Had to make a short riser pipe to allow kit to fit without having to remove the front body panels.

DSC03454.jpg

Kit contains a venturi type air pump so you need an air compressor to benefit from this kit.

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This procedure I will apply. The device they have is different (on a principle different from Venturi).DSCF6193.JPG

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The wax element works, and yet we have encountered problems with temperature regulation.
The plastic materials used in the manufacture of the casing are not good for the proposed purpose - they have succumbed due to temperature and mechanical stress.
That's why I chose the metal.
I have the possibility to make the new plastic case but I do not want a plastic thermostat!
Cracked plastic thermostat I know, recently happened on a hard road, the car is Smart 450 CDI Brabus and the road is a difficult one.

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I am confident my Gates will work fine once I have added the metal clamps to hold it together. My modified Gates worked very well for two years until its two halves came apart. 

The plan is to fit multiple C clamps made out of stainless steel plate and hold them on with a hose clamp strapped around the belly of my Gates. Should not take long to sort out. 

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I increased the hole in the case for matching the thermostat.
Also a thread on the end of the wax element.

Thermostat size (comparative)

 

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When are you fitting your new thermostat in your Smart?

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As soon as possible, if I find the rest of the material, namely:
- nipple for bypass
- nipple for cabin heater
- aluminum bar (or PTFE) for the end of the wax element
- lathe available.
The most important thing is the time ... I work on the thermostat "between drops"

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Last night I put an aluminum bolt at the end of the wax element .

DSCF6737.JPG

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To compensate for the exaggerated play of the bow, I carefully gripped the first and last springs of the stainless steel spring.

DSCF6738.JPG

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