Classic Alfa Forums

I'm well happy with my £15 Ebay new thermostat purchase.
Somebody really needs to come up with a way of repairing these.

That looks good. It it brand new or reconditioned? I spent most of Sunday sitting on the garden bench trying to clean mine up, gave up, found the spare and cleaned that instead but neither look as good as that one. My son cleaned the alternator housing for a pound. What was wrong with the oldun.

Mine must be the earlier one.
The cover is held by 2 bolts, and I presume there is an old fashioned thermostat inside, but it works, so I've never opened it.

Ah I had not noticed - yep mine are the bolt together one too and I assumed this one was - I wasn’t looking for no bolts so to speak.

They do have and old fashioned thermostat inside and I believe you can take them out and buy a replacement - although I’ve never tried. My housings are rough and dragged up off the seabed quality.

Andrew Fitton wrote: ↑Wed Jun 03, 2020 8:28 am That looks good. It it brand new or reconditioned? I spent most of Sunday sitting on the garden bench trying to clean mine up, gave up, found the spare and cleaned that instead but neither look as good as that one. My son cleaned the alternator housing for a pound. What was wrong with the oldun.

It's a brand new one. Well new old stock. They are really hard to find now.

alfadave wrote: ↑Wed Jun 03, 2020 6:37 pm Mine must be the earlier one.
The cover is held by 2 bolts, and I presume there is an old fashioned thermostat inside, but it works, so I've never opened it.

I think I'm right in saying the top of the housing is the thermostat and they are also very hard to find

The sealed one is the later design, thermostat is indeed inside it.
The old original Sud design had a two bolt housing top that allowed the 'stat to be changed.
Just if you attempt be really careful, the steel bolts sitting in the alloy housing for years are extremely reluctant to come out...

There’s been 3 types over the years a Removable cover (2 bolts) with a regular stat inside then they went over to a removable top with integral stat and the final incarnation was the unserviceable pressed together POS That had a habit of splitting if you don’t quite have enough antifreeze in the winter

LooLooSud33Spider wrote: ↑Wed Jun 03, 2020 8:29 pm There’s been 3 types over the years a Removable cover (2 bolts) with a regular stat inside then they went over to a removable top with integral stat and the final incarnation was the unserviceable pressed together POS That had a habit of splitting if you don’t quite have enough antifreeze in the winter

HI loo. Have you ever come across a way of fixing the later types. The ones that come up for sale usually are going for big money

I’m glad I just cleaned the mating surfaces with nothing more than my fingers - I think I’ve got the bolt together but ‘stat pressed inside sort.

The bolts on mine came out no prob. We’ve got some lovely light flint gravel round the house and I proceeded to drop the bolts in the gravel and spent a full hour on my hands and knees until I found them.

A magnetic pick up stick is a great tool.
Or just kick them in the gravel, and use new ones!

Hi,
in forums I have see some modifications to rebuild alfa 33 thermostat as a serviceable one;
one of the most simple mod. I think was one I have see photos posted by Yuri on a Fb group:

After opening the alfa 33 thermostat and removing top and inner worn out cartridge,
he welded an alu flange/plate and added a top cover with integrated cartridge/valve from
alfa 75 type ( start open at 83° degree instead of at 86° degree as modern alfa 33 but fit easily
as cartridge is same small dimension of original alfa 33 /sud ) with two bolts

Sealing can be by gasket, o-ring, or sealant;
I think you just have to be accurate about best height/relative position when maching pieces,
the cartridge have a lower smaller disk that moving vertically (3? 4? millimeters)
act as a second valve when descending in the lower part of alfa 33 thermostat housing,
you have to calculate millimeters so that when the disk will be in lower position
possibly it will almost close the lower inner pipe in the housing but possibly
still don't impact with it too much ( theres is a small coil to compensate for such
eventual impact but for more long lasting of the wax acting as actuator in the cartridge
I think it is better if avoiding that, if possible best choise could be leave about 0,5 millimeter free gap )

Ps.: with the same starting point of welding an alu plate at the alfa 33 thermostat housing,
I searched for alternatives using separate top cover and inner cartridge with various temperatures
from other cars, I still have not try directly, probably need a bit more work than the alfa 75 thermostat,
but if someone want try the mod I can share some possible compatible top cover and inner cartridge

Would it be easier to use an early Sud type housing, with removable thermostat?........if that is possible

.........or maybe have it refurbished by Sudshop for £40?