Do I have a thermostat problem?

[PaddyB]

Good morning  - Looking to get some assistance in diagnosing a suspected problem with the thermostat on the 156 Selespeed.

The 156 Selespeed temp gauge does not show an operating temperature that you would expect to see in a car that operates normally. ie I owned an MX5 and after a few km's it showed an operating temp of sitting exactly mid way on on the gauge. The heater was effective also.

My observations are that the Alfa takes longer to warm up, i.e. 30 minutes of driving and only then the needle moves marginally from the cold indicator.... the heater takes a long time to blow heat.... Should I sit still in traffic after the 30min period the needle rises a little more however when I drive off.. the needle falls to the minimum again.

I understand that I may require a new thermostat? however it could also be a temperature sensor? Based on the above, can any one advise me as to what the problem may be?


Manythanks in advance

[John Hanslow]

The car should warm up in a few minutes of driving with the heater kicking in.  In reality it does take a km or 2.

In my experience of 156/146 TS vehicles, the temp guage only goes up to 90 degrees afer the car has been idyling for an extended period of time and the thermo fan then kicks in and it is back to 70/75

If that is not the case, I would have it looked at. Perhaps it is a issue with the thermostat and at the same time flush out the radiator as well.

[Steve S]

Faulty thermostats are common on these cars and you have all the symptoms of a stuck open thermostat. They only seem to last 5-10 years. The dealer may say it is "within limits" but they go by some very loose limits!

One test is to leave the car idling, wait for the radiator fan to cycle on and off. If the gauge shows 90 or somewhere in the middle then that confirms the thermostat is stuck open. If the gauge stays where it usually does it could be a faulty gauge or sender.

[colcol]

I have a 10 year old 156 JTS, and its on to its 3rd thermostat, yours has the classic symptoms of a stuck open thermostat, when you are in traffic it will go up to 90c, but driving on the freeway or suburbs, it drops back to halfway between 90c and 0c, you will have more fuel consumption when its cold as it will be running a richer mixture to cope with the colder temperatures, the engine wear will go up due to the less than ideal temperature, and the heater won't work as good, there are many thermostats to choose from and prices vary greatly, the ones that are a bit cheaper, most likely won't have a temperature sender, so you will have to use your old one, they are quite expensive as the thermostat comes in a housing with pipes coming off it and a sensor, the thermostat itself is built into the housing and cannot be replaced on its own, the twin spark, JTS and V-6 have all different thermostats, Colin.

[AndrewK]

I had exactly the same symptoms in my 147 TS and a stuck open thermostat was the cause. Got one in from EBSpares and it works a treat - temp goes up to 90 degrees after about 5 mins on the road and stays there. Fuel consumption noticeably reduced.

[colcol]

And engine life is extended it, because its heating up quicker and running hotter, therefore getting better combustion, but thats not important, whats important here in Melbourne during winter is that the heater comes on quicker and hotter, surely thats got to be worth the price of a new 'stat', Colin.

[Navman]

I would just change the Thermostat as the symptom you describe point to this.It is a relative simple task, just make sure you replenish the coolant as you will lose some.. The 156 thermostat seems to fail quite often. I am speaking as one who recently just completed this task..
Hope this answer has helped you.
   

[colcol]

Hey Navman, what brand of thermostat did you use? i have gone thru 2, both genuine BEHR brand, the one in now is a non genuine Italian brand, interesting to see if it outlasts the Genuine Alfa ones, they should last longer than they do, after all, i don't think of a thermostat as a consumable, the twin sparks and JTS 'stats' are different, Colin.

[alfagtv152]

Hi All,
I have the same symptoms with my 166 and am certain it is the same stuck thermostat,is there any way to free them?.
Any suggestions as where to buy them,online sires?.
Cheers
Andrew

[colcol]

If you got a stuck thermostat, then replace it, get on the 166 Ebay site, try the UK, The Alfa Workshop, EB Spares, there are so many, The Spare place in Adelaide, Turin Imports in South Australia, have a look in your club magazine for Alfa Wreckers, the choice is yours and tell us how you go, the only way to free them is to take out the housing and replace the housing with a new thermostat, what usually happens, is that they have a gas or bi-metal spring in the thermostat, and when it gets hot, it opens the valve in the thermostat, and lets the water thru, when it gets cold the valve closes, and stops the water flow and diverts it, as the water pump is still pumping, you could take the thermostat out and cook it in a saucepan with a cooking thermometer, and see if its opening and closing, a stuck open one when cold is faulty, but if you find its faulty, then you have to wait while the new one turns up in the post, which means you can't drive the car, just get a new one, put it in, drive the car and test the old one to confirm whether it has to be stored in the round filing cabinet, [rubbish bin], Colin.

[trippytipo]

Is it a big job to replace the thermostat on the 156? Would like to have a go at it myself if I don't need any specialist tools, that is.

Should you just replace the thermostat or the entire thermostat block?

i.e. http://ebspares.co.uk/alfa_156/25_and_32_thermostat/info.cfm vs http://ebspares.co.uk/alfa_156/25_thermostat_block_complete/info.cfm

Thanks!

[colcol]

The thermostat only comes in a complete assembly, as a lot of thermostats do in the current era, if you are talking 4 cylinder, it bolts onto the end of the cylinder head, a bit fiddly, as its a bit hard to get to, remove the flexiable air pipe that goes to the aircleaner to give you room, drain the coolant first, by removing the bottom radiator hose, then remove all the hoses from the thermostat housing, undo the retaining bolts and remove the thermostat, Colin.