Technical temp gauge

[rc822]

When I have to inside fan on max temp the engine temp gauge never gets to half way, but when I turn the temp down from max, the engine temp gauge goes to half way. Any ideas why it does this??

 

[Ziggy122]

So it only does this when its on temperature

You dont have the fans running?

With how cold it is outside - the extremem cold air been blasted past the radiator and heater matrix - the cooling system is been tooo effective

But its also a sign of the thermostat no longer adjusting how it should to engine temperature
It should get upto temperature (half way) and stay there regardless

Ziggy

 

[fingers99]

Heater matrix is, in effect, a second radiator. But you may have an incipient thermostat issue.

Halfords ones are OK, branded ones are generally OK, beware of anything that does not have a manufacturer's stamp on the thermostat.

 

[rc822]

Well I noticed this today, be driving the car for 30mins and yes the fan was on speed 4. The engine is a 1.2 8v if this helps, also could it be air in the system?

 

[fingers99]

Unlikely.

 

[Ziggy122]

as said the cabin heater is a 2nd radiator and a fan
the fan pushs air over the heater matrix and out the vents

the extra cold air flow cooling the coolant down means it drops

i have done this before - when the fans are on high - the engine is running at idle at the lights or after a roll down a hill the temperature often drops a little, but should regenerate within about 1minuite i would have thought

Ziggy

 

[rc822]

Ok so ive just sat in the car and run it at idle, when the fan temp is not on max its all ok, the temp gauge stays at half, but as soon as the fan is on max temp the temp gauge moves down two notches. It never goes over half.

 

[fingers99]

Seems fairly normal -- if mpg is an issue, though, I'd change the stat. Easy job, stat is £15 or so.

 

[rc822]

I might be replacing the stat soon, just a few questions, do I need to put some gasket sealant between the engine block and the stat gasket and what torque do I tighten the 2 bolts on the stat at? Thanks

 

[fingers99]

A lottle sealant helps, but isn't strictly necessary.

I've no torque figues for the stat -- just do it by feel, remember, the fasteners are pretty small.

 

[rc822]

Also would I need to remove the coil pack or can I get away with not removing it?

 

[fingers99]

You can get away without removing it, depending on what tools you have available.

Removing the coil pack holder certainly makes access easier.

You'll loose a little coolant, so bleeding and top up advised.

 

[Ziggy122]

if no history of a coolant change - a stat change is perfect time todo it too!

I like removing the coil pack - it makes it 10x easier to re-align them back up as you face it up and do the bolts up

ziggy

 

[rc822]

Ok I think I'll remove the coil pack, also what your technique in bleeding the system

 

[homeward]

Ok I think I'll remove the coil pack, also what your technique in bleeding the system

This guide should help...! Just be very, very patient; and, if possible, have the car facing upwards a little....

 

[Ziggy122]

when i do a stat change - which i could forwell end up doing a guide for - as yes
mine is failing again!!

I like to drain the system and spend 10mins cleaning the block up while its soft and squishy and easy to pull off

I like the coil pack out - makes access ALOT easier

Sealing wise - i put some sealant on the new stat - then fit the cork gasket you get with it - let it set a little so it cant move as easily

Then i seal the other side up and then stick the bolts through - remove the sealant off the bolts btw

When fitting - make sure its correct way up
I do it up by hand till i cant do hand no more
Then the ratchet comes in - pulling it in as flat as possible
i dont torque these bolts - as thats asking for trouble - there small and subject to abuse
So i get them to a firm - once the sealant has gone off - just nip them a little more - make that nice thick gasket squish and make a perfect seal
No leaky stats for me

Bleeding can be a pain in the ""Horse"", it takes some bleeding sometimes

Ziggy

 

[rc822]

Ok thanks also how do you get coolant out of the rear bleed screw, when I open it nothing comes out?

 

[fingers99]

Ideally you want the heater (but not the heater fan) on full.

It can be worthwhile doing the bleed on the front screw with the engine off and cold, replacing the front screw and coolanr pressure cap, then running the car up to temperature with the rear screw a little bit open. Close it when water starts to come out.

 

[randomizered]

ALso, a few revs helps speed up the water pump and therefore pressure up to the bleed screw.

 

[rc822]

So ive fitted the stat and is now perfect, its sorted out the fan problem. But im am having trouble with the bleeding process, I cant get any coolant out of the rad screw :/