E36 328 overheating

A thermostat has 2 modes of action,one is to open up at the correct temperture to allow the coolant to be cooled, and 2  it restricts the amount of flow around the engine,ie if it is pumped to fast it would not have enough time to cool off so not fitting one is just as bad and will eventually get to hot.The flow has to be exactly right to stay at the correct temp.Also a lot of vehicles have a duel stage thermostat which allows one port to be shut while another opens at different tempertures so leaving one of these out is suicide.I can,t understand why when it was apart they never put one in,does,nt make sense,they have to take apart again to fit it.

yep - 328 so straight six...

got a bit worried when I saw it start to overheat again, but looked under the bonnet and saw coolant spewing out of the plug between the rad and the expansion tank... one way or another, then plug had started to shear, allowing coolant to bubble through the 'x' where you put your screwdriver...

still trying to find a replacement... hoping that my nightmare is soon over...

LuxAuto wrote: he's talking pure crap. why would a head require settling down? if it has been distorted by the heat, it will be distorted. Running it without a thermostat is not going to un-distort it.  A leaking head gasket is usually the first things to indicate a distorted head, but they are pretty tough so you shouldn;t have caused any damage if you turned the engine off straight away, unless of course you are running a straight six, in which case, it is probably easier to distort due to the length of the head.

agreed. Lol! what the hell else would a 328 be?!?

Well I got it back from the 'repair' shop, and it now seems to cool properly, so it seems that it was the thermostat which was the problem....

He acknowledged that it would make sense to put one in again, but that he wanted to make sure that the 'head settles down'... Given that the car was stopped as soon as the red light came on, I'm hoping that there wasn't any head damage, but I guess that time will tell... Or is it more obvious than that?

jonathanlewis19 wrote: I left it to the garage to sort out - they've just told me that they've taken the old thermostat out but not put a new one back in. They're telling me that the car will be fine without it, but will just take a little longer to warm up... Are they right? I'm worried

 

Thanks god for guys like these, and especially Lux. I wouldn't know what to do if they'd said I could drive the car without a thermostat.

Kin' Cowboy garages.

Well they've put it back together now, so that's kind of it done. The good thing is that I'll take it for a spin tonight - if it all stays at or below temperature, then I know that the problem was the thermostat - then I can just get them to put one back in... Expensive I know, but prob better than putting another one in, thinking it was fixed, bolting it all back up and then finding it was still f***ed...

Thanks for your advice though guys - will definitely get a new one put in once I know that it was just the thermostat that was the problem!!

You're all stars!

No!

They are just bodging!

An engine runs at its most efficient when it is at a certain temp, usually in the 90s, this is where you get optimum efficiency.  By taking the thermostat out, you no longer have any control over the temp of the engine.  it will always run overcooled and will cause more wear and tear on the engine, plus the engine will consume more fuel fuel. 

And in the winter, you can forget about having decent heating, especially if you drive on the motorway!

Other effects of overcooling will be an inability to burn off any moisture in the engine.  This will increase wear and tear as it will destroy the oil and can cause pitting of the components due to water ingress.

You have every right to be worried.

Why can;t they put a new thermostat in?  Don;t they have one?

Edited by LuxAuto

I think all thermostats are manuafactured that way, (wax) so BMW can't be blamed for being cheap. 

Apart from the lack of a fail safe, it's quite cleaver and very simple.  What i usually do, whenever I change the coolant, and depending how easy access is, is to replace the thermostat as well.  On non-bmws, they only tend to be £5-7 so it's worth it and saves having to drain the coolant out again.

 

The thermostat?

If it failed in the open position, the engine wouldn;t be overheating, it would be overcooled and the heater would never get warm.

Most thermostats fail in the closed position because a mechanical spring is used to return the valve to the closed position. 

A thermostat works on the principle of heat expanding the wax in the thermostat.  As the wax is in a sealed unit, it has nowhere to go and the resulting pressure pushes against the spring, which opens the valve. 

When the engine cools down, the wax contracts and spring pressure will force the valve closed.  that's why a thermostat hardly ever fails in the open position, but it does happen, but the symptoms at the moment doesnt suggest this.

Edited by LuxAuto

It's a late 1996 model which means (I think) that it got the metal impeller... Although I've seen conflicting information on this...