Bongo Fury

Hi all....
A couple of months ago i replaced the rear heater matrix,re plumbed it in and got my air-con fixed and regassed.
Since all this was done i seem to have a more varying temperature reading on the secondary gauge which is fitted to my van.The mazda gauge always sits at 11 o`clock.
The sensor is tapped into the small bore hose that goes into the expansion tank.
The temp seems to sit around 76-78 degrees when moving and the bottom hose to the radiator can often be "just warm" and not "hot".
The heaters always blow hot when turned up and to be fair the van runs fine.
I have never seen the gauge drop below the 76ish mark when moving.
If the stat was at fault it would either be cold or overhating??
Can this fluctuation be caused by me always using the air-con as the fans cut in and out?
When the rear heater was bypassed and the air-con did not work the secondary temp gauge always sat at around 82 when moving,only rising when stationary.
Hopefully its nothing to be of concern and it deffinately would not have been noticed if the secondary gauge was not fitted as the Mazda gauge always sits at 11o`clock.
Thanks in advance for any replies.....

The standard temp gauge sits at 11 O'Clock pretty well permanently as it is heavily damped.

Did you bleed the system after working on the rear matrix? Possibly an air lock?

Sounds pretty good to me.
In the position you currently have the sensor, coolant leaving the head has a fair length of large bore pipework to travel through before it reaches the sensor, so it will loose heat.
If you had the sensor taped to the top hose as it leaves the cylinder head, you would get a more meaningful reading as in this position you would get a reading MUCH closer to what the thermostat is seeing (which should be around 82/86).
Having said that, IMHO, your system appears to be working exactly as it should.

Bear in mind we're talking V6 here, so running temperatures & thermostat opening may be slightly different to the diesel. If I remember, I'll check the spec of the thermostat when I get home later.

From the engine manual, V6 'stat should open thus:

Start temp: 81.5 - 84.5
Full temp: 96
Full lift (mm): 9 or above

Bob wrote:The standard temp gauge sits at 11 O'Clock pretty well permanently as it is heavily damped.

Did you bleed the system after working on the rear matrix? Possibly an air lock?

Yeah,she was all bled afterwards...

Cheers for the replies folks,studying the replies you guys have posted i think its just me being paranoid.
THANKS ALL.......

just for the record i have a good gauge fitted in the same place on my diesel, and get exactly the same readings.
sounds good to me. .

Simon Jones wrote:From the engine manual, V6 'stat should open thus:

Start temp: 81.5 - 84.5
Full temp: 96
Full lift (mm): 9 or above

Thought so Simon. Basically the same as the diesel. What is the part number for the petrol stat - do you know?
Petrol engines do run at slightly lower temperatures I've heard, but basically the same system as a diesel (coolant wise).

widdowson2008 wrote:What is the part number for the petrol stat - do you know?).

V6 'stat Mazda part JF0115171