325i Running Cold

[Riley]

i have a 1991 325i motorsport and the temp gauge does not get up to the centre, i have just replaced the thermostat, but it has made no difference. does anyone know why it is running cold?

[kam-325i]

How far up does the needle go ?

Just below halfway is normal...

[Riley]

about half way between centre and the mark before. How can that be normal? surely centre is normal?

[kam-325i]

about half way between centre and the mark before. How can that be normal? surely centre is normal?

Anywhere just above the quater mark and upto the halfway mark is "Normal". Mine runs just below halfway. But if i am driving hard i can get it to just go over halfway....

If all things are ideal......then halfway is normal....but they are not......

[stevetigger]

I once owed a 325i Sport that always run at 1/4, never did me harm!

[Morat]

What we're saying is that the gauge is often a lying git. If you're worried about the temp your engine is running at then you're probably going to have to investigate the gauge first, then fix any problems that come to light.

[pnd]

The difference between a quarter and halfway is tiny in temperature terms also there are different thermostats. Given the choice I'd prefer lower than halfway.

[Fushion_Julz]

Sounds like either the gauge isn't very accuarate or the sender is giving dodgy readings....

I bought one of these http://www.maplin.co.uk/module.aspx?Tab ... 3&doy=29m8

(only they were half price last month) and it shows the temperature accuarately on the sender and at any point on the cooling system so you can see if the gauge is inaccuarate or not...

[Riley]

What is the correct temperature menat to be anyway?

[Fushion_Julz]

From memory....Thermostat starts to open @ 82C fully open @ 92C

I would expect around 92-99C at "normal" with a fully warmed up motor at the top (inlet) of the rad and significantly cooler at the outlet...
And no major hotspots on any part of the water jacket....

Can't recall what the presurisation factor of the system is, but I wouldn't be expecting to see a boiling coolent (assuming you have the correct coolect cap and the correct amount of antifreeze in the ssytem) until 108C at least....

[kam-325i]

what the presurisation factor of the system is

The wierd effect that cause's a higher boiling point of water/water mix.....

[Fushion_Julz]

cheers, Kam...what I meant was I can't remember how much the system gets pressurised by...or, in other words, how high the new boiling point of the presurrised system is!

[kam-325i]

If i remmeber rightly, (but dont qutoe me !!!)the boiling point of a "normal" summer water/anti-freeze mix in a M20 is 110°C, so you was not far off.....

[Fushion_Julz]

cooool...my memory isn't so bad after all!!
(or yours is as bad as mine )