Temp Gauge seems to flucuate more since new thermostat

[jason1987]

i changed my thermostat on saturday and now when im driving along around 40 it goes from 80-90c, im sure it used to stay at about 70 constantly then got warmer when i was stoppped.

[lozz]

Might be a slight air-lock
or false reading, Temp sensor issue,

as a guess,

[keppler]

im having the same problem as you had before the thermostat change. i can't get my temp above 70 when cruising but when I stop its goes to about 75. My thermostat has been playing up since I bought my car and Im going to change it tomorrow or next day.
Tbh, I would have thought that a fluctuation between 80 and 90 degrees was fine as the thermostat is designed to open at 83 degrees

[jason1987]

maybe it wasnt working properly before and now it is and thats why its different

[Gary406]

i changed my thermostat on saturday and now when im driving along around 40 it goes from 80-90c, im sure it used to stay at about 70 constantly then got warmer when i was stoppped.

as long as it doesnt go way over 90 it will be fine. if it does go over 90 say to 100 then stop and let cool down before continuing home

as lozz said you may have airlock from changing thermostat. did you bleed the system properly after you changed it ?

leave expansion tank lid off and let engine get upto temp so thermostat opens and lets any trapped air out. open bleed valves to let trapped air out ?

[jason1987]

i bled the system but i didnt do it with cap off, had cap on and bled the thermostat screw and then the one by top of engine bay near front

[steve_earwig]

That's not right. There should be 3 bleed screws (I can't remember what car you have but they all should be similar), the 3rd should be on one of the heater pipes. You need to bleed it with the cap off because there's a lot of the system as high as the expansion tank & if the level drops too far you're wasting your time.

Have a squint at this viewtopic.php?f=5&t=4482&p=43212&hilit= ... est#p43188 . I also did a how to on the Wiki here http://www.pug406.com/wiki/index.php?ti ... _System%29 . You don't really need the funnel but it makes the job idiot-proof, otherwise you've got to watch it like a hawk as the engine warms up.

[jason1987]

ive got an sri turbo,so where at the bleed screws? i did one on stat housing and one which i think is the heater at top of engine bay

[steve_earwig]

Right by the windscreen? (I'm guessing your car isn't hanging by its rear bumper...) I'd expect to see one on the rad. Somewhere.

[jason1987]

oh also ive only got one cooling fan working, the big one. will this effect it? im guessing the smaller fan runs slower and keeps it cool constant whereas the big fan comes on when it gets too hot? so my cars getting to the 2nd point of cooling each time.

[lozz]

ithink one of the fans is for air-con

most fans have two speeds, ive never seen or heard one cut in on a 406 so idont know what temp the fan shouid cut in or what speed it shouid run at,

[jason1987]

well just tried to bleed the system after my drive home and it squirted everywhere lol, guess youre not ment to do it once its been driven? also couldnt find a bleed screw on radiator, can only find the 2 one on stat and one by windscreen, heater matrix i think it is?

[steve_earwig]

I can't find it in the diagrams, but then I can't find the one on the heater hose either Maybe it never had one, maybe it's a pattern rad which lacks it, either way I reckon you'll have to bleed it as per and not worry about the missing bleed

[jason1987]

also i almost lost the screw cap, id be screwed if i lost that wouldnt i? wouldnt be able to use car and where am i gonna buy another cap that fits

[kevtherev]

I can't find it in the diagrams, but then I can't find the one on the heater hose either Maybe it never had one, maybe it's a pattern rad which lacks it, either way I reckon you'll have to bleed it as per and not worry about the missing bleed

i could only find 1 bleed screw on mine it is the 1.8 but you wouldn't have thougt there would be that much difference... i certainly havent got 1 on the stat housing as i replaced that with genuine dealer part. the haynes says there is 1 on the back of the head somewhere but buggered if i could find it and there aint 1 on the rad either.
the only bleed screw i could find was on the heater pipe right up against the bulkhead, it trickled out ,so i gave the top rad hose a good squeeze and that shifted the airlock i had. worth a try.

well just tried to bleed the system after my drive home and it squirted everywhere lol, guess youre not ment to do it once its been driven? also couldnt find a bleed screw on radiator, can only find the 2 one on stat and one by windscreen, heater matrix i think it is?

i just left mine idling for 5 or 10 mins, with the expansion cap off and got it warmed up. wouldn't it squirt because the system has pressurised and its being pushed through the bleed valve??

ithink one of the fans is for air-con

most fans have two speeds, ive never seen or heard one cut in on a 406 so idont know what temp the fan shouid cut in or what speed it shouid run at,

mine cuts in around 100.