Alfa Romeo Forum banner

1 - 14 of 14 Posts

·
Registered
Joined
·
989 Posts
Discussion Starter #1
Hi, sorry to open another thread about thermostat but I'm a bit unsure. I have a 06 plate gt, 58k miles. I only do short trips, like 3 miles so car doesn't really get upto proper temp. Recently I have noticed a drop in mpg from about 27mpg to 24mpg, although 3mpg isn't much, it is when only doing 27mpg in the first place! Anyway, went for a 20mile round trip today and noticed after the car got to 90 degrees as normal, it dropped back to about 70 degrees and stayed there. My heating was on high to warm car up, not air con, when my interior warmed up and the fans were blowing less, I noticed the temperature slowly creeping back up to about 80-85 degrees. I can't decide if this is normal or not, I'm noticing lately in a morning, it's blowing more out of exhaust, not smoke but steam/water. Is this a sign the stat is on its way out or just because of colder UK weather? Only had car for 6 months and not really had heating on prior to last 2 weeks so don't know what's normal or not! Had a 156 previously and changed the stat but it was more clear cut than this time. Any ideas if I need to change it or not and if so, is it the same procedure as on my old 156? Thanks in advance.
 
G

·
Guest
Joined
·
0 Posts
Hi Matt.

On a JTD that kind of scenario would be normal working conditions for a diesel thermostat.
On a V6 it's only a matter of 5-7 miles to get to 85 degrees and sitting in traffic, 92 degrees before the fans kick in to return it to 85, that's regardless of interior heating settings.

The JTS is very similar to a TS in terms of thermostat temperature and IIRC with my old TS it was within 8-10 miles and 83 degrees and rarely got above 90 degrees even in summer traffic conditions. I did notice with it though that if the heater was on full it would take a little longer but would never drop below 80 degrees on the temperature gauge in the winter.

I would hazard a guess that you have some air trapped in the system and it simply needs bleeding. Many owners forget to turn the heater up to maximum temperature during the bleeding process and as a result the matrix can have a small air lock in it as when the temp is set to low. it cuts off the flow to the matrix. Then when you come to use it on high temp, that trapped air now travels throughout the system giving a false reading.

Try bleeding the system first mate... I would hate for you to waste money if there is nothing wrong with the thermostat.
If you are not too sure of the process let me know and I will take you through the process step by step ok:thumbs:
 

·
Registered
Joined
·
989 Posts
Discussion Starter #4
Thanks graemeo, how would I bleed the system exactly? Just went for another drive after the engine had cooled down and noticed it warmed up a lot quicker and stayed on 88-90 with no heating on!
 

·
Registered
Joined
·
9,912 Posts
after it cools down just take cap off, should sort it
ps if engine warms up and you got heater on ,obviously engine will take longer to heat up
pps no valve on matrix its constant flow and heat is changed by the way of flaps
 

·
Registered
Joined
·
989 Posts
Discussion Starter #8
I will let it cool down tonight and take cap off tomorrow when cold and see what happens. What I don't understand is today I did a 20 mile journey and got about 25mpg, stop start traffic. My normal drive is a 5 minute drive at 2.8 miles, 4 times a day.I'm getting the same mpg whether it's a long journey or short journey but in the summer that 20 mile journey would have got about 30mpg so it's 5mpg down. Would having the heating (not air con) and also the colder weather have such a negative impact on mpg?
 

·
Registered
Joined
·
9,912 Posts
I will let it cool down tonight and take cap off tomorrow when cold and see what happens. What I don't understand is today I did a 20 mile journey and got about 25mpg, stop start traffic. My normal drive is a 5 minute drive at 2.8 miles, 4 times a day.I'm getting the same mpg whether it's a long journey or short journey but in the summer that 20 mile journey would have got about 30mpg so it's 5mpg down. Would having the heating (not air con) and also the colder weather have such a negative impact on mpg?
yes
 

·
Registered
Joined
·
989 Posts
Discussion Starter #10
Can I ask a real newbie question! I'm going to do the check in the post you mentioned tomorrow morning about starting from cold and feeling the top pipes to see when they get hot. I'm a bit unsure what pipes you mean, do you mean the top pipe that goes to where the coolant is stored?
 

·
Registered
Joined
·
989 Posts
Discussion Starter #13
Ok, I think my stat is ok. Did the test this morning and stat opened about 87 degrees and then dropped down to 70 before climbing back upto 90 ish. Took 15 minutes to get upto temp thought. Funny thing, when it was upto temp, I switched heating on and it dropped down to 80-84 degrees. Must just be the cold weather?
 

·
Registered
Joined
·
989 Posts
Discussion Starter #14
To finish this topic off, I did a 80 mile round trip yesterday and averaged 37MPG!! Wow, never seen them figures before so cannot be running cold. Stat opened correctly and temp fluctuated between 80-86. Never went to 90 unless I turned the heating off!
 
1 - 14 of 14 Posts
Top