[zenmaster]

Hi all☺
Alfa 156 JTS selespeed 2003.
I love this car.
I know it's getting old.
Changed thermostat last week because temp was very slow to climb, cabin heat non existent and nasty burning smell from thermostat area when warm. Oil was getting black so assume engine not cooling properly?

Very pleased with myself (I am no mechanic/engineer but I sort of know my way round an internal combustion engine and how it works) Big thumbs up for the "how to change your thermostat guide" found on this forum.

So to test. Ran engine up to temp. Cabin heat was amazing and engine was reaching temp nice and steadily. Then it went past 90 and carried on steadily and did not stop!!!. Turned off engine.

No leaks. No loss of coolant
Rad top hose warm
Expansion tank hot
Rad fins cold resulting in no cooling fan kicking in.

Read a lot here about air locks so detached small hose from thermostat to expansion tank (removed tank cap) and blew down hose.
Coolant rose in the tank from bottom hose connection. No idea why I did this but it seemed like a good idea at the time just to check fluid was circulating around the cooling system.

Ran engine still same issue.

Is it likely my new thermostat is not working?
Has water pump broken? How do I know?

Couple of other pointers. It does emit "disco steam" from exhaust whilst warming up. Opened bleed screw on top of rad and that emitted cold coolant from rad.

Thank you in anticipation

 

[Ex Alfa man]

Just a couple of thoughts off the top of my head.

You don't mention whether you ran the engine up to to temp whilst bleeding the system on changing the thermostat? Also assuming you bled the system did the radiator remain cold to the touch all the time? Maybe you have a blocked rad?

I

 

[zenmaster]

Hi ex Alfa man.
Thank you for your consideration.
I didn't run up to temp and bleed.
Will try and do that this week if I get time.
I think I'm concerned about running engine to temp with bits of hose disconnected but I'll try anything to get it right.
Thanks again

 

[David C]

Rad fins cold resulting in no cooling fan kicking in.

The fans are triggered by the ECU using the temperature sensor on the thermostat.
A cold rad wouldn't prevent the fans from running.

 

[David C]

.
I didn't run up to temp and bleed.
Will try and do that this week if I get time.
I think I'm concerned about running engine to temp with bits of hose disconnected but I'll try anything to get it right.
Thanks again

You don't disconnect any hoses.
Just run up to temperature with the cap off of the coolant expansion tank.

 

[Pud237]

You can also bleed these using gravity - fill the coolant expansion tank up to the brim then open the bleed nipple on the radiator. Air will come out first, pushed out by the coolant rising up the radiator. Eventually pure coolant will start to come out, at this point you can close the bleed nipple. As long as the level of the coolant in the tank doesn't drop below the height of the bleed nipple this will work. If you're left with excess coolant in the tank you can divert the return into a suitable container and then start the engine and let it pump itself out.

 

[yellow horse]

You can also bleed these using gravity - fill the coolant expansion tank up to the brim then open the bleed nipple on the radiator. Air will come out first, pushed out by the coolant rising up the radiator. Eventually pure coolant will start to come out, at this point you can close the bleed nipple. As long as the level of the coolant in the tank doesn't drop below the height of the bleed nipple this will work. If you're left with excess coolant in the tank you can divert the return into a suitable container and then start the engine and let it pump itself out.

air lock for sure,had the same problem with my 2.0l t spark after timing replace,a ******* to bleed the air out, run the engine and keep the bottle full and open,it will eventually blow the air out.ps important did you had the heat up maximum in the car wher running the engine?if not air will be in the hoses and the internal radiator.

 

[jwq]

.....ps important did you had the heat up maximum in the car when running the engine?if not air will be in the hoses and the internal radiator.

actually, shouldn't make a difference as there is no valve in the interior heater, it's always in-circuit.... air temp is regulated by air mixing flap....

 

[zenmaster]

The fans are triggered by the ECU using the temperature sensor on the thermostat.
A cold rad wouldn't prevent the fans from running.

Thank you for this. That's excellent info

 

[zenmaster]

You don't disconnect any hoses.
Just run up to temperature with the cap off of the coolant expansion tank.

Thank you for that. Very useful

 

[zenmaster]

You can also bleed these using gravity - fill the coolant expansion tank up to the brim then open the bleed nipple on the radiator. Air will come out first, pushed out by the coolant rising up the radiator. Eventually pure coolant will start to come out, at this point you can close the bleed nipple. As long as the level of the coolant in the tank doesn't drop below the height of the bleed nipple this will work. If you're left with excess coolant in the tank you can divert the return into a suitable container and then start the engine and let it pump itself out.

Excellent walk through. Many thanks

 

[zenmaster]

air lock for sure,had the same problem with my 2.0l t spark after timing replace,a ******* to bleed the air out, run the engine and keep the bottle full and open,it will eventually blow the air out.ps important did you had the heat up maximum in the car wher running the engine?if not air will be in the hoses and the internal radiator.

Yes I had the heat up but I was only testing for leaks at the time. Great news though keeping my fingers crossed that I can manage it. Brilliant

 

[zenmaster]

actually, shouldn't make a difference as there is no valve in the interior heater, it's always in-circuit.... air temp is regulated by air mixing flap....

Good to know. Thanks a mil

 

[kandlbarrett]

It could still be as simple as thermostat not opening. What make of stat fitted?

 

[Mystic]

If you can hear it gurgling and belching with it stopped it'll be an enormous air lock but sounds too much like classic knackered thermostat. It should open at about 88 degrees and at that point the top hose to radiator should get properly hot as the water is allowed to go through, and of course the temperature gauge shouldn't keep going up.

I'd get yet another thermostat from somewhere else. If water is coming out of the top bleed valve on the end of the radiator then the radiator is full so you can't have much air in the system. Shouldn't be enough to cook it anyway. Sounds like a damaged or faulty thermostat.

 

[zenmaster]

It could still be as simple as thermostat not opening. What make of stat fitted?

Still my gut feeling
See reply below

 

[zenmaster]

If you can hear it gurgling and belching with it stopped it'll be an enormous air lock but sounds too much like classic knackered thermostat. It should open at about 88 degrees and at that point the top hose to radiator should get properly hot as the water is allowed to go through, and of course the temperature gauge shouldn't keep going up.

I'd get yet another thermostat from somewhere else. If water is coming out of the top bleed valve on the end of the radiator then the radiator is full so you can't have much air in the system. Shouldn't be enough to cook it anyway. Sounds like a damaged or faulty thermostat.

I think you maybe correct.
Tested again last week. No air airlocks or gurgling or dropping off of coolant level.
Had it idling for about 1 1/4 hours with expansion tank cap off. Temp gauge sat between 110 and red line the whole time. Guess what the rad fan started to work! A bit. To be fair engine didn't boil or steam or do anything wrong. But rad was still cool.
Conclusion must be thermostat issue but I find it hard to believe that a new (admittedly generic) thermo that fits perfectly and was ordered as per vehicle reg is so wrong.
Any how will try a different thermo and report back.
Have to say you folks have been stirling in your support and advice and cannot thank you all enough
Hopefully conclusion soon and I can yet again show everyone else who doesn't own an Alfa what a great car they are.?

 

[blis]

Thermostat change should just work... i own a golf gti 1990, 16v, and those are notorious for air locks.

Whenever a thermostat is in question, i feel the temps of the bottom hose to start.

Then you might have the option of peeking into the collant temp port, but I think it easier to remove it completely.

When i changed the one on the jts 2004 2.0 16v, it was calcified due to tap water and electolysis caused by the collant temo. So be sure to finish this job withndeminerlaised water.

I also flushed the heater matrix out with a hose fitting and flushed theough the block via the collant reservoir. All indicators seem that your thermostat is stuck shut, if you remove it qnd placemit in a pot of boiling water you might get some results. Also from my experience with the golf, the fan thermo switch on it is on the rad, not sure where the one os on the alfa. But my old radiator had seen better days and when I replaced it, the fans behaved more like they should have. I guess there wasnt enoigh flow pasg the thermoswitch that triggered the fans.

The thermostat in the alfa originally had a rail, the afte market was a plane jane mounted in a housing. The original with the rail was subject to the calcification and im happier with the after market. In would get the thernostat back off, pain I know and check there isnt something stuck inside preventing it opening, then check and replace if it doesnt open in the pot test

Dont keeep overheating the engine either, bad things happen as the prssure inceeases

 

[jwq]

did you try a comparison between the temp displayed on the gauge, and temp measured via OBD ?
gauge and obd (=ECU) use different temp sensors, and temp as displayed on gauge is sometimes quite far off..... Temp as measured by ECU is the one used to switch the fans.

 

[plastic penguin]

Had a similar problem with my 2002 Sportwagon.

Have you inspected the radiator carefully? The fins could be blocked. This'll result in the water not circulating (the previous owner could have used some sort of sealant)