Thermostat housings

[Bren]

Why do manufacturers make these out of plastic?

 

The fiesta's is leaking less than two years after replacement - surely a plastic housing against an alloy block will never work due to different rates of expansion.

 

The rubber seals inside the housing have obviously failed - I will have to spend on a genuine ford one this time.

[sierraman]

Had a similar problem on my old mans mondeo. K-seal did an admirable job at stopping it. Been a year now still no leaking

[Conrad D. Conelrad]

My last two cars have had the thermostat housing fuse with the studs and in both cases required an entire afternoon of heat, plus gas and violence to remove. I wish they'd been made of plastic. 

[Station]

Felicia had a problem with these, the innards cracked because the spring in the thermostat was too strong.

[lisbon_road]

The question asked was why they're made of plastic.

 

Because it is cheap.  A plastic moulding will be a fraction of the price of an aluminium casting.  Used to be all nylon I think, now more and more polypropylene.  It is also light, but cheap is the main reason. 

 

At a guess, I'd say about 1/3rd the price, that is a guess though.

[Mr_Bo11ox]

Plus, plastic is a good material for these, it costs nowt and weighs hardly owt. Its easier to get off after a few years and theres no reason at all why it should be more leak prone, you can design an O-ring seal that will accept the relative expansions of the housing with no problems. If you have bought a cheap ass one that’s not had its seal designed/tested properly, thats probably your problem.

[vulgalour]

I'd expect the housings to be better in plastic for the reasons Mr B points out.  You should see the state of the metal casing on the Princess, and what's worse is that "they all do that, sir"!  I already have plans laid out for a replacement thermostat housing and it'll likely be a plastic thing because it'll just be easier to  keep in good order.

[Noel Tidybeard]

angyl a thought- if you can get an elbow that fits the head you could check the set up on an old clio where the stat actually sits in the hose and maybe adapt that

[Angrydicky]

Plastic thermostat housings? You're obviously buying cars that are too modern and newfangled. Having said that, alloy thermostat housings are a pain in the arse when they weld themselves to the metal studs and you end up having to take chisels, molegrips and angle grinders to them to get the flipping things off.

[Bren]

Plastic thermostat housings? You're obviously buying cars that are too modern and newfangled. Having said that, alloy thermostat housings are a pain in the arse when they weld themselves to the metal studs and you end up having to take chisels, molegrips and angle grinders to them to get the flipping things off.

Modern, newfangled, and shit.

[vulgalour]

@Frank:  That's near as damn it exactly what I'm doing because it should all just swap in and out as needed.  Bags of room to modify and modernise what was a pretty appalling design from the factory.

[Junkman]

Mo matter which material thermostat housings are made of, they are made by the devil.