Rubbish plastic thermostats

[Maxfly]

I have been lucky in that only one thermostat has failed on me over 13 years and so far, 4 KV6 engined cars. (It was replaced on the ZT just before i got it though).
I thought Kaisers thermostats were still available and i 'think' dmgrs have a form of upgraded thermostat in stock?!

[SD1too]

Originally Posted by Maxfly

I have been lucky in that only one thermostat has failed on me over 13 years and so far, 4 KV6 engined cars.

Thank you Gary for sharing your experience with us. It demonstrates that the original thermostat is not inherently unreliable.

I'm told by another member that the DMGRS "upgraded" thermostat has aerospace epoxy resin applied around the welded seam. This is pointless since, contrary to common belief, the seam does not leak (although I cannot vouch for the "keyhole" method of installation when it may well suffer undue stress); it's the 'O' rings which are responsible.

Kaiser's metal parts use the same 'O' rings as the MGR plastic parts. Now there's a clue!

Simon

[Dorset Bob]

Originally Posted by SD1too

Kaiser's metal parts use the same 'O' rings as the MGR plastic parts. Now there's a clue!

Simon

If the Kaiser one doesn't leak but the OEM plastic ones do, and if the 'O' rings are the same, then it can't be a problem with 'O' rings.

[Mr Toad]

Exactly. If the plastic ones were not such rubbish they wouldn't fail. I am afraid that I am not convinced that it is just the seals. I am not mucking about any more I have ordered a metal one which I hope will be fit and forget. The only problem is they are out of stock till March April however iI can wait.

Martin

[trikey]

Best in mind the plastic stats will now be moulded using Chinese plastic, I guarantee that will be a much cheaper alternative than the material that was supplied by DuPont.

[marinabrian]

Originally Posted by Maxfly

I have been lucky in that only one thermostat has failed on me over 13 years and so far, 4 KV6 engined cars. (It was replaced on the ZT just before i got it though).
I thought Kaisers thermostats were still available and i 'think' dmgrs have a form of upgraded thermostat in stock?!

You have been lucky, only a 25% failure rate !

The worst I've seen is three failures on one car in six months, and none were fitted using the keyhole method either.

In two cases the straight pipe burst, and another was running constantly at 78 degrees.

All three were the "improved" Chinese variant masquerading as "genuine" Rover

The fourth thermostat fitted to the car is still in operation now five years later, and it is a Kaiser metal variant, that in itself must say something

Brian

[SD1too]

Originally Posted by Dorset Bob

If the Kaiser one doesn't leak but the OEM plastic ones do, and if the 'O' rings are the same, then it can't be a problem with 'O' rings.

Ahh, the answer lies in what happens to the 'O' rings when mounted on two very different materials.

Originally Posted by trikey

Best in mind the plastic stats will now be moulded using Chinese plastic, I guarantee that will be a much cheaper alternative than the material that was supplied by DuPont.

The plastic is not the issue Andy, it's the 'O' rings which leak.

Simon

[Dorset Bob]

Originally Posted by SD1too

Ahh, the answer lies in what happens to the 'O' rings when mounted on two very different materials.

Yes, I agree the answer lies in the two different materials.
The answer is that the plastic ones are prone to leaking and the metal ones are not.
I think everyone can draw their own conclusions.

Originally Posted by SD1too

The plastic is not the issue Andy, it's the 'O' rings which leak.

Simon

If it is true that the only failure is the 'O' rings, I will ask you the same question again.
You state that the 'O' rings are the same on both types, so why do they leak on the plastic ones and not the metal?

[Maxfly]

Originally Posted by marinabrian

You have been lucky, only a 25% failure rate !

The worst I've seen is three failures on one car in six months, and none were fitted using the keyhole method either.

In two cases the straight pipe burst, and another was running constantly at 78 degrees.

All three were the "improved" Chinese variant masquerading as "genuine" Rover

The fourth thermostat fitted to the car is still in operation now five years later, and it is a Kaiser metal variant, that in itself must say something

Brian

Yep definitely, when the stat went on my pbt ZS I can’t honestly say which part went, it had an AA warranty so once I spotted it was leaking it was called in, garage repaired it and I picked it up fixed, for the next 3 years it was fine till I wrote the car off.
My Goodwood Green ZS was fine on its original stat till the next owner blew the engine.
My xpg ZS, I cannot say for sure but the first owner may have had to change the stat and I’m not sure where that car is now but have checked and one of the subsequent owners had to replace the stat on that.
But while I personally have been lucky I have seen many owners on various forums over the years who haven’t been when it comes to thermostat failures. What I haven’t looked more into is the type of failure but I know I have seen mention of the o rings failing, but I have also sent owners saying the plastic housing was leaking at the joint

[steve-45]

Originally Posted by trikey

Best in mind the plastic stats will now be moulded using Chinese plastic, I guarantee that will be a much cheaper alternative than the material that was supplied by DuPont.

Surely not, I can’t believe that the Chinese would use lower grade materials