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Erratic temperature

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erratic
3K views 43 replies 11 participants last post by  Alecto28 
#1 ·
Hey guys,

Just drove 130 miles tonight. The temp on my 1.6 156 ts kept going up and down.

It often went up to 110, and then suddenly dropped down to 70-75.

Don' t think it should be going as high as 110 and wait there for any length of time.

Do you think the thermostat is gone? I replaced it last year but the way it drops so quickly suggests that the thermostat is opening late.

What do you guys think?

M
 
#36 ·
Hi!
Did you get this problem fixed?
I have the same problem in my 1.6 TS.

I can drive it many miles and the temp is about 70º and then it just goes up to 110º or, in some times, to max! I turn it of for a minute or so and turn back on, rev it up and it goes to 70º again in like 2 seconds! I have noticed that the temperature some times goes near 110º and all of a sudden drops to 70º again! It drops very quickly!
 
G
#37 ·
Check the temperature via independent means, i.e. the ones which don't depend on the gauge.
Plug in some diagnostic software (Alfadiag, Unidiag, FiatECUscan) and see what the sensor really reads AND/OR
take the expansion cap off and measure the coolant temperature with a thermometer.
As you can probably tell, I hate my temperature gauge - after its decalibration made me spend 100+ EUR on a new thermostat.
 
#38 ·
The reading on the dial is correct, just replaced the temperature sender and the reading is exactly the same.

When the gauge reads around 100º, 105º, the water boils, so it is reading correctly.

I have already ordered a new water pump, thermostat, and a head gasket.

This problem started when some weeks ago a water tube broke and the temperature went to max because the coolant got out. I fixed it and it drove fine for 4 days and then started to do this.

When the coolant got out the car's tempearture went to max and it shut of, so I think I may have blown the head gasket.
 
#41 ·
Yes, the fan works. It kicks in at 95º or so.
If I disconnect the plug from the temperature sender it then starts to work in the lower speed and after a few seconds it goes full speed, which indicates it is working properly.

The radiator appears to be in very goos shape. The fins are clean and very rigid all through the entire radiator.

Also, when the temperature rises I still have warm air blowing inside the car.

Thank you for the replies! :)
 
#43 ·
I'm beginning to think that this problem is no big deal, I found this on Alfa156 net

The water temp rises too slowly, hitting 90c° only after 10Km (driving
about 90Km/h with 5c° outside), when temp reaches 90 it suddenly drops
to 75-80 and then rises a little but usually is always below 90c°.

Reason:
Alfa uses a different way of showing the temperature compared
to i.e. Opel, Audi, VW. I guess Seat is VW so......
The difference is that in fact the temperature always goes up and
down because there is a thermostat (in all cars!!) that opens when
the cooling circuit reaches a certain temperature like 90dgr.
When the thermostat opens, a whole lot of relativaly "cold" cooling

drops from 90 to 70-75dgr.
Alfa shows this immediately on the temperature indicator whereas many
other cars measure an AVERAGE temperature that goes up and down very
slowly and certainly will not show the peaks like the Alfa way.
I guess this is done because the "normal" car driver will get in panic
and goes and see their dealer to check if nothing is wrong and Alfa is
of the opinion that Alfisti, as real, true car drivers, as enthousiastic
and knowledgeable car dirvers and can "see through" this.

So, forget about bothering the dealer, just enjoy your Alfa and keep
a regular eye on all engine fluids; don't forget the fuel tank ;-)

Thanks to Gert-Jan from Holland for this info!
 
#44 ·
Hi!

Just to let you know that it was the head gasket.
Replaced it and now its perfect!

I replaced the Head gasket and new head bolts, water pump and thermostat.

Since I had the head out I had the variator replaced and installed the Alfa retention valve to solve the variator problem for good.

Here it is:





 
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