Does thermostat opening temperature matter?

[Tomscar]

Maybe a strange question but I still haven't worked out yet whether it makes much difference.
Here is the back story … earlier in the year I discovered that there was a small leak from where the thermostat housing meets the engine block … not that surprising as the thermostat was still the original and now almost eighteen years old.
I ended up shearing both of the bolts that hold the thermostat cover on but at least I knew for certain that I had the plastic cartridge type that opened at 87°.
I decided to go for an aftermarket replacement thermostat housing by Topran, complete with 87° thermostat and G62 sensor, advertised as being the correct one for my 2002 1.4 petrol BBY.
I installed the pre assembled unit when it arrived and checked the the coolant temperature on VCDS Lite ... a consistent 82°. I checked the new thermostat and found that I had been supplied with an 82° thermostat made of metal and certainly not as advertised.
So does it make much difference?
... the car appears to start and run normally with no fault codes showing ... the only thing I have found is that the hot air doesn't get much above 24° from the vents as verified using a thermometer and HVAC module on VCDS Lite.
Anyone else replaced their thermostat housing with an aftermarket one or had similar issues?

 

[Tomscar]

Well folks, I'm one step closer to solving the riddle of two different thermostats.
I've been emailing back and forwards to the nice man at VWSpares.
He has convinced me that the thermostat housing with the Audi part number 032121111AM and made by Himmermann is directly compatible with the Topran 110350 version and is common to both the Himmermann metal 83° thermostat (with the Himmermann thermostat cover, part number 032121121G) and the Henschel plastic 87° thermostat (with the Henschel thermostat cover 032121121K).
Anybody that's come across this will realise that the metal one twists into and is held in place by the cover and the plastic version clamps between the cover and a circular socket within the housing.
Next job is to remove my metal thermostat ... the wrong one for my car ... and test this information!!
I'll keep you posted in case anyone is unsure and considering doing this job.

 

[Tomscar]

Today I took off the thermostat cover to help solve the riddle of the two thermostats ... hopefully this will be useful information for anyone planning to replace their housing on a 1.4 Petrol BBY with an aftermarket Topran 032121121G.

1. Pre-drained 1.5 litres of coolant by taking off the top narrow pipe from the expansion tank and feeding into a cola bottle ... just idled the engine and let it pump out ... job done in less than a minute.
2. Put plenty of rags under the thermostat cover and disconnected the hose .... much easier with angled hose pliers!
3. Disconnected the upper gear cable from the linkage and moved it out of the way ... no tools required,
4. Pulled the wiring harness from it's mount ... it was in the way.
5. Unscrewed the two hex bolts from the thermostat cover ... it's an 8mm socket or spanner, with enough room even on the bottom bolt for a socket with a 1/4" drive.

I knew I had been supplied with the wrong thermostat but is the housing with Audi (32121111AM) and its direct replacement from Topran (032121121G) really common to the metal (83° Himmermann) and the plastic cartridge (87° Henschel) considering that they are physically not only different sizes but held in position two different ways?

Well the answer is .... yes, the housing is common ... now without a shadow of doubt.
The Topran housing contains the fitting for the plastic cartridge and is redundant if the traditional metal one is fitted.
The thermostat covers are different as most of you will know ... the cartridge version uses the Henschel 032121121K cover and the traditional metal uses the Himmermann 032121121G ... but both fit to the housing in the same way.

All I have to do now is buy a new 87° cartridge thermostat and reuse my original cover ... and hopefully back to original spec!!

Here is a photo looking inside the housing and you can clearly see the part where the plastic cartridge sits. I tried my non working original thermostat and all fits back together as it should:

All the best and I hope the information is useful ... Tom

 

[Tomscar]

I was going to buy all genuine replacement parts but surprised by the quotes that have come back from my local Skoda dealer, am I so far out of touch with reality, maybe these are the going rate ... can anyone give me a heads up?

£38.57 + VAT - G62 Temperature Sensor 059 919 501 A
£19.39 + VAT - Thermostat 032 121 110 B
£10.78 + VAT - Thermostat Cover 032 121 121 K

Many thanks ... Tom