Car overheated, would it have killed the thermostat?
Car overheated, would it have killed the thermostat?
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jimmy156

Original Poster:

3,834 posts

216 months

Wednesday 6th April 2011
quotequote all
Hi all, just a quicky.

To cut a long story short, my car overheated RAC man diagnosed a broken thermostat so "smashed" (his words) the thermostat out of the housing. Turned out it was the water pump not the thermostat. He claimed the thermostat would have been knackered by the car overheating anyway, which seems doubtful to me. New thermostat and housing has cost me £50 so I wanted to know if i would have had to replace it anyway.

Cheers, James

FranKinFezza

1,073 posts

208 months

Wednesday 6th April 2011
quotequote all
A failed thermostat can "cause" overheating but i doubt hot water would damage
the stat seeing as that is the environment its supposed to operate in!

I'll not get in to mr AA mans treatment but if it were mine i would not be best pleased!

The Wookie

14,209 posts

257 months

Wednesday 6th April 2011
quotequote all
It's pretty unlikely, or at least I've certainly never heard of an overheat causing a thermostat to fail, only vice versa

E30M3SE

8,493 posts

225 months

Wednesday 6th April 2011
quotequote all
Agree with the above.

jimmy156

Original Poster:

3,834 posts

216 months

Wednesday 6th April 2011
quotequote all
That what I thought to be honest. The whole situation has been a total nightmare (I'm in Surrey, the cars in Leeds along with half my luggage 'cos i forgot to put my tax disc in, but that's kind of my fault!). I would have hoped that a trained RAC bloke would have to be pretty sure with his diagnosis before irreparably breaking a part! Maybe a quick email to the RAC will help.

Gandi69

85 posts

191 months

Wednesday 6th April 2011
quotequote all
Sounds like they are taking you for a ride. "Smashing" the stat out of its housing?

jimmy156

Original Poster:

3,834 posts

216 months

Wednesday 6th April 2011
quotequote all
Gandi69 said:
Sounds like they are taking you for a ride. "Smashing" the stat out of its housing?
That was the word he used, I think it wasn't a case of unscrewing it it actually had to be broken to get it out.

shouldbworking

4,801 posts

241 months

Wednesday 6th April 2011
quotequote all
On the other hand in the course of the investigation of the cause of overheating odds are any garage would have had to check it anyway and smashed it then - assuming it really was the only way to gain access to it.

Buzz word

2,028 posts

238 months

Wednesday 6th April 2011
quotequote all
I assume it wasn't diagnosed at the road and you were towed but the guy didn't return the parts? It could have just been an oversight on his part. He may not have meant he literally smashed the thermostat housing as that would have done no one any good. If the stat was bad he could have refitted the housing and got you on your way.

jimmy156

Original Poster:

3,834 posts

216 months

Wednesday 6th April 2011
quotequote all
shouldbworking said:
On the other hand in the course of the investigation of the cause of overheating odds are any garage would have had to check it anyway and smashed it then - assuming it really was the only way to gain access to it.
You could gain access to it easily, well the housing unit anyway. He broke the thermostat out to allow me to drive home. i.e. to fix the issue.

ETA: it didn't fix the issue, it was the water pump.

Edited by jimmy156 on Wednesday 6th April 17:19

jimmy156

Original Poster:

3,834 posts

216 months

Wednesday 6th April 2011
quotequote all
Buzz word said:
I assume it wasn't diagnosed at the road and you were towed but the guy didn't return the parts? It could have just been an oversight on his part. He may not have meant he literally smashed the thermostat housing as that would have done no one any good. If the stat was bad he could have refitted the housing and got you on your way.
Yeah i was towed in the end, he originally said it was the 'stat and when that didn't fix it he said it was the water pump (which it was) .

He didnt smash the housing but broke out the internal gubbins to try and fix the problem with the plan of refitting the housing and me driving home with no thermostat. Obviously it wasn't broken until this point (unless the car getting hot could have broken it, which is what this thread was about.)

littleredrooster

6,371 posts

225 months

Wednesday 6th April 2011
quotequote all
If it had boiled dry, then yes - I've seen wax-type thermostats shagged by overheating.

jimmy156

Original Poster:

3,834 posts

216 months

Wednesday 6th April 2011
quotequote all
littleredrooster said:
If it had boiled dry, then yes - I've seen wax-type thermostats shagged by overheating.
The was still plenty of water in the system, hadn't lost a drop!

Buzz word

2,028 posts

238 months

Wednesday 6th April 2011
quotequote all
jimmy156 said:
Yeah i was towed in the end, he originally said it was the 'stat and when that didn't fix it he said it was the water pump (which it was) .

He didnt smash the housing but broke out the internal gubbins to try and fix the problem with the plan of refitting the housing and me driving home with no thermostat. Obviously it wasn't broken until this point (unless the car getting hot could have broken it, which is what this thread was about.)
I don't think it would have broken due to the overheat but it would be just the order of diagnosis. Arguably he should have checked it before he broke it but he may not have had a kettle or a way to make it open in the van.

I would attack an overheat like this:

inspect for damage of the system
check hose temps
squish hoses to ccheck for airlocks
check thermostat
check pump.
sniff test.

I would guess that was what he did but got to check the thermostat and decided to bypass straight away rather than check it. He got to the point where he had done all that could be done at the roadside without specific parts. If the housing and stat were intergrated somehow I guess nothing was recoverable. It's probably a little cavilier to have not checked the stat before breaking it but I would accept what he did as I can see the logic and that he may have had no way to test it. Telling you it would have been broken smacks of fobbing you off a bit I guess.

davepoth

29,395 posts

228 months

Wednesday 6th April 2011
quotequote all
jimmy156 said:
The was still plenty of water in the system, hadn't lost a drop!
With no water pump, it would have been quite possible for it to have been dry with water in the system.

saxxeblt

87 posts

235 months

Wednesday 6th April 2011
quotequote all
I can understand what's gone on here, if you were overheating the thermostat may have been jammed shut stopping the water circulating. By removing the 'stat, you can possibly unblock the flow. I've had a 'stat stuck in it's seat and had to "break" it to get it out. Then he could have tested the flow without the 'stat and then found the waterpump was u/s, it's exactly what I would have done.
HTH

Eggman

1,253 posts

240 months

Wednesday 6th April 2011
quotequote all
If it's your 156 we're talking about then it's usual to replace the thermostat at the same time as the radiator once the cooling fins have disappeared due to rust. Running hot for any length of time seems to cook the thermostat, but they fail in the open position and the result is that the engine doesn't get up to temperature with the new rad. That's what happened to mine, and as far as I've been able to establish it's the norm for Alfas. Haven't heard of them failing closed, but wouldn't rule it out.

NHK244V

3,358 posts

201 months

Thursday 7th April 2011
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Had it a few times, WP fails so we replace it only to descover the stat has colapsed shut and the temp sender is shagged sometimes along with the ECU temp sender and the rad switch.
Pug 106 last DEC had all these after a WP failier.