coolant header tank expansion tank

[Grapes]

It might be coincidence since a lot of them look alike but has anyone ever compared the Alfa 33 one with the one in the Murena? I stumbled upon a picture by accident and am now looking at several pictures from the ones on Politecnic, Simon and Matra Magic and random examples of Alfa 33 ones and to the eye they look completely identical. However price wise the Alfa one costs about a third of the ones from the Murena specialists... For example: https://www.alfashop.co.uk/products/5031001-sud and https://www.simon-auto-shop.de/06033

Also, I read on Roy's alternatives list that the 10 psi filler cap is kind of unique to the Murena but when I google around I see plenty of other 10 PSI rated caps that are short reach. They're all 60mm and around 25-27mm high though so maybe that's where the difference lies?   <<EDIT:: I misquoted here because of this website:
https://www.asap-supplies.com/products/driveforce-pressure-cap-short-reach-10-psi-206910 where 10PSI is followed by 80kPa which as Roy kindly pointed out is incorrect!!>>

It would be really nice is the Alfa tank is a match though. Those seem to be relatively common.

[roy4matra]

It might be coincidence since a lot of them look alike but has anyone ever compared the Alfa 33 one with the one in the Murena? I stumbled upon a picture by accident and am now looking at several pictures from the ones on Politecnic, Simon and Matra Magic and random examples of Alfa 33 ones and to the eye they look completely identical. However price wise the Alfa one costs about a third of the ones from the Murena specialists... For example: https://www.alfashop.co.uk/products/5031001-sud and https://www.simon-auto-shop.de/06033

Also, I read on Roy's alternatives list that the 10 psi filler cap is kind of unique to the Murena but when I google around I see plenty of other 10 PSI rated caps that are short reach. They're all 60mm and around 25-27mm high though so maybe that's where the difference lies?

Please don't mis-quote me.  My website says the cap pressure was given as 80 kPa which is 11.6 psi.  That is what makes it rare. 
70 kPa (or 10 psi) and 90 kPa (or 13 psi) caps are common, but ours is halfway between the two.

It would be really nice is the Alfa tank is a match though. Those seem to be relatively common.

The Italian one is the same, which is reasonably well known.  It's the same as on some Lancia too.

Roy

[Grapes]

Apologies Roy, I amended my post.

I'm surprised but happy to hear that the tank similarity is common knowledge. I looked at your site http://www.matraclub.org.uk/Murena.html but didn't see it mentioned...

I've done some further research into these caps and I get the feeling websites sometimes convert these pressures incorrectly. I found some people on forums mention 24mm deep 0.8 bar caps for other cars (e.g. early X19 apparently) but they also came to the conclusion they are very hard to find.

Then I looked for pictures on the Matra specialists and found that the ones at Matra Magic are 4lbs according to the picture: https://www.matramagic.co.uk/2020/02/01/eu-no-change-here/Header-Tank-Cap-Murena-p381275839 I'm not quite sure what to make of that.

[Matraman]

The expansion tank on my 2.2 looks very different from the Alfa 33 one. In the Simon catalogue it's this one: https://www.simon-auto-shop.de/epages/Simon-Auto-Anlasser-Lichtmaschinen.sf/en_GB/?ObjectID=164208210
It's a used one, so does that mean there are no new ones now and the Alfa one can replace it if necessary? Presumably using the original cap.

[Grapes]

Looks like that alfa/lancia one is only the same as the 1.6 murena... I wonder how much shape matters as long as it has the right amount of hose connections in the right places and can hold enough coolant...

[roy4matra]

Apologies Roy, I amended my post.

Thanks.  Yes you should never take for granted conversions on websites as correct as I've come across so many over the years with incorrect information and inaccurate descriptions.  Many on eBay are even breaking the trades description act by advertising something they are not!  Recently something was advertised as 'Genuine' of a particular brand when in fact it was a cheap Chinese/far east copy.  I got my money back but it wastes time and leads you to be suspicious of everything.  Other incorrect items such as a torch being advertised as being an led version when it was actually a normal incandescent bulb type meant yet again getting my money back and more delays getting what I wanted.

Similarly don't take cross referenced alternative parts as being correct unless you've double checked them.

The Italian roughly 'triangular' header tank was fitted to the early Murena both 1.6 and some early 2.2, but later they all got the later type rectangular tank.  The Italian one was unavailable for some years which is why I never bothered with it on my website, but some have been remade recently it seems.

Roy

[Grapes]

Ah that makes sense, Is the newer rectangular one also used in other cars like the triangular one?

Those incorrect descriptions are really doing my head in. Especially when it comes to things that I simply don't know much about, it's extra annoying. And even on topics I am familiar with I still find it sometimes hard to determine if it is as advertised.

[roy4matra]

Ah that makes sense, Is the newer rectangular one also used in other cars like the triangular one?

It probably was but I never found out where it came from. (Does anyone else know where the larger rectangular header tank came from? Or what other car had it fitted?)  Matra usually bought parts that were being made for other manufacturers and cars, as that was far cheaper than having to design, and make their own, for many common items fitted to all cars, such as door handles, electric motors (wipers & windows) interior mirror, column stalk switch assemblies etc.  Even things like the radiator came from another car but with slight modification (brackets added) for the Murena.

Those incorrect descriptions are really doing my head in. Especially when it comes to things that I simply don't know much about, it's extra annoying. And even on topics I am familiar with I still find it sometimes hard to determine if it is as advertised.

Never rely on photos for one thing as many use a 'stock' photo in their adverts.  Unless it says that the photo is of the actual part, then treat it as possibly wrong.  And many who advertise their parts as 'will also fit...' are very often wrong simply because they regularly do not know a specific car, like ours, and just assume it will fit.  They are simply trying to make it seem like it fits lots of things to increase their sales.

Roy

[Oetker]

Bit late reply.
Confirmed fitting the 1.6 and for 6 years on the cr now.
The cap is 0.5 bar so i used the original and that fit fine.

[roy4matra]

Bit late reply.
Confirmed fitting the 1.6 and for 6 years on the cr now.
The cap is 0.5 bar so i used the original and that fit fine.

Whilst the cooling system will run with only a 0.5 bar pressure cap, the correct one is a 0.8 bar pressure cap as stated in the official Matra workshop manual.  A reduced pressure will mean the boiling point of the fluid is reduced so the coolant will start to boil earlier which is important on this mid-engine configuration.  Even the front mounted 1.6 and 2.2 engines in the Alpine/Solara/Tagora had a 0.6 bar pressure cap.  With the radiator a long distance from the engine and the engine being more enclosed than a normal front engined car, it will probably reach boiling point too early and any bubbling in the engine can cause damage similar to cavitation, or local hot spots where the coolant is no longer against the metal for direct temperature transfer, because there is steam there.  I recommend sticking to the correct rating.

Roy

[Grapes]

Bit late reply.
Confirmed fitting the 1.6 and for 6 years on the cr now.
The cap is 0.5 bar so i used the original and that fit fine.

Yep, that's what I did as well. The original is 0.5 so I simply used the old cap which indeed is a good fit.

I do believe I seen an 80kpa short reach cap on a tractor supply site somewhere during my search... 🤔 I wonder why I didn't link or haven't mentioned it previously. Maybe I misremember it.