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Discussion Starter #1
As the title says I just changed the Thermostat on my 1.6 twinspark.

It was fairly easy apart from getting the original Alfa clips of the hoses :rant: things!!

So. my questions are:

How much coolant should the system take? I put 2litres of anti-freeze in the expansion tank and it was full! I ran the engine up and went for a drive, it got up to temperature quickly, almost reaching 100 before the stat opened (Or the fan come on?) then it cooled down to about 75-80. I will recheck the level with the cap off tomorow morning and top up if needed.
The problem is my system is currently 100% Coolant, which I'm guessing isn't ideal?
Would it cause a problem if I can only put in say another half litre tommorow?

Also, I read about the bleed screw on the rad, should I use this to help bleed the system?

Thanks.
 

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first and foremost you dont go for a drive until stat opens:rolleyes: as any air locks will get replaced and could remove all coolant from your tank or beltch it out of tank
 

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when i changed my stat i dropped bottom hose off of rad so that i could change most of the coolant, took about 5 litres. 2.5 water & 2.5 anti freeze.

if just changing the stat it would be alot less than this as the rad would still be nearly full
 

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when i changed my stat i dropped bottom hose off of rad so that i could change most of the coolant, took about 5 litres. 2.5 water & 2.5 anti freeze.

if just changing the stat it would be alot less than this as the rad would still be nearly full
2 litres stat change on jtd16v
 

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Discussion Starter #5
first and foremost you dont go for a drive until stat opens:rolleyes: as any air locks will get replaced and could remove all coolant from your tank or beltch it out of tank
I waited until the guage read 90 and the top rad hose was hot to the touch, then I went for the drive.... the rolly eyes were not necessary :tut:

Thanks for the info AVaflaTI, I will take the cap off and check it tommrow morning, as long as there is other coolant ie water in the system it should be ok?
Just worried about running 100% anti-freeze
 

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Hi it is actually written somewhere in the manual , how much coolant your system contains,if only the thermostat has been removed without the lover hose at the point of the radiator has been off , there shold bee a lot of coolant left in your system.
The head of the engine where thermostat is in one end , the water pump in the other, can hold spaces of air trapped ,it is outmost important to get rid of that air or the waterpump wont work!!!!!:(
Så yes bleed the radiator upper plastic screw until coolant comes out and not air,close and proceed!
AND pump using your hand on the upper hose to the radiator.
I think this very useful link is just what you needed :https://sites.google.com/site/alfaromeo156thermostat/
look at foto 156.23 it´s my hand !!!!! and
https://sites.google.com/site/alfaromeo156cooler/
Ps you can drain enough coolant out at the went screw and add calcium free water.

William Lütken:cool:
 
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A pair of re-useable clip pliers and those silly alfa clips become easy... And easy to re-fit :)
 

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Discussion Starter #8
So when you use the radiator bleed screw, leave the engine running, undo the screw until water comes out, then tighten up again?
 

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I waited until the guage read 90 and the top rad hose was hot to the touch, then I went for the drive.... the rolly eyes were not necessary :tut:

Thanks for the info AVaflaTI, I will take the cap off and check it tommrow morning, as long as there is other coolant ie water in the system it should be ok?
Just worried about running 100% anti-freeze
you stated you ran engine up and went for a drive then said stat got up to temp quickly .....

reason stat opened at 100c was air lock in system at stat not allowing coolant to be in contact with it:thumbs:
 

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Hi,
Coolant system takes 6.9 litres, replaced my thermostat and radiator recently, drained about 6.5ish litres out (measured and marked line on inside of bucket to catch old coolant), when filling up with new coolant, take note on how much has come out before you replace with new, that tells you how much air is trapped!
When filling up, unscrew radiator bleed screw, water should trickle out.
When confident you have max coolant in, start her up! But turn on the heater to HOT! And fast, when gets up to running temp, (after thermostat has opened) (88 - 90deg) unscrew radiator bleed screw a little so that water trickles out, the pressure will force air out immediately!

Then stop engine, wait 5-10mins and unscrew expansion tank cap to free trapped air from the air bleed pipe next to cap, wait till engine is cold and top her up!
 

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Hi,
Coolant system takes 6.9 litres, replaced my thermostat and radiator recently, drained about 6.5ish litres out (measured and marked line on inside of bucket to catch old coolant), when filling up with new coolant, take note on how much has come out before you replace with new, that tells you how much air is trapped!
When filling up, unscrew radiator bleed screw, water should trickle out.
When confident you have max coolant in, start her up! But turn on the heater to HOT! And fast, when gets up to running temp, (after thermostat has opened) (88 - 90deg) unscrew radiator bleed screw a little so that water trickles out, the pressure will force air out immediately!

Then stop engine, wait 5-10mins and unscrew expansion tank cap to free trapped air from the air bleed pipe next to cap, wait till engine is cold and top her up!
dont see point of heater on hot as there is no control valve on 156's as far as im aware just flaps that control heater temp/cold flow
 

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I thought that, but it's a comforting sign I guess that the air is bled from the heater matrix when hot air is pumping through.
I did try it once without the heater on and there was an airlock in the heater matrix, it went soon as I turned heater on, it's no harm in trying it if it does or doesnt make a difference.
 

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OK I'm feeling a bit paranoid now... I replaced my stat two weeks ago. I bled it but I'm not sure if i did it properly.

The car is running at around 87deg as reported by AlfaDiag... Ive driven about a 1000kms in 35 degree celcius weather and the water level is constant..

What, apart from teh obvious engine failure, are the symptoms of an air lock?
 

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OK I'm feeling a bit paranoid now... I replaced my stat two weeks ago. I bled it but I'm not sure if i did it properly.

The car is running at around 87deg as reported by AlfaDiag... Ive driven about a 1000kms in 35 degree celcius weather and the water level is constant..

What, apart from teh obvious engine failure, are the symptoms of an air lock?
air locks seem to be apparant when temp gauge sweeps back and forth as if system is breathing
 
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you will never get ALL the coolant out of the system even if you drain the coolant rad & the heater matrix, the reason is that there would be at least a litre in the engine block.

after a stat change I always drive with the heater on FULL HOT & the coolant cap loosened but only drive 0.5 miles from my house & then back into the yard, doing this 3 times, checking coolant level in between each trip.

My advise would be to check the coolant level in the morning, when its cold, & top upto the MAX level. You should grand after that, unless there are any minor leaks.
 
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you will never get ALL the coolant out of the system even if you drain the coolant rad & the heater matrix, the reason is that there would be at least a litre in the engine block.

after a stat change I always drive with the heater on FULL HOT & the coolant cap loosened but only drive 0.5 miles from my house & then back into the yard, doing this 3 times, checking coolant level in between each trip.

My advise would be to check the coolant level in the morning, when its cold, & top upto the MAX level. You should grand after that, unless there are any minor leaks.
 

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No need to panic! There are many return pipes and air bleed pipes returning back to the expansion tank, as long as you make sure all the air is bleed from the radiator it's a no brainier, after an engine run, unscrew the expansion tank cap to release excess air, you may hear some bubbles as the fluid is gulping the coolant, this means all the air is getting out.
87deg is correct running temp, I thought mine was right temp at 75deg when someone said the thermostat had gone!
 
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