has my themostat failed in open?

[Darkstar]

drove about 52 mile this morning, on main roads average 50mph, heater on full 32'.

temp gauge only just starting to rise on arrival at destination, heater barely warm and tm2 stating engine temp 55'

i assume this is not normal? any other suggestions would be helpful

thanks

[The Great Pretender]

Not sure but if your heater is only just warm there is a problem. When I was monitoring my system I had a sensor in the coolant flow on the outlet from the head reading real time temperature and the Mazda gauge doesn't move until the coolant gets to virtually 70c.

[Northern Bongolow]

bit strange this one really.is it a diesel?.
i think the short answer is possibly.
the long answer could be,how old is the stat and coolant,is the coolant up to strength,(if its mostly water not antifreeze it will be a better coolant than anti /water mix,) how old is the rad/pump.
the heaters should warm quite quickly,then later the rest of the system,it sounds like its having to warm all the system in one go.your tm2 and mazda temp gauge sound like they are saying the same thing,both are telling the proper temps,and saying possibly something is wrong.
i can think of no other cause that would give the above symptoms,apart from both heaters on full blast from the minuite you jumped in and start the motor,and your heaters are super efficient at removing the heat from the system,and you drive with a very light right foot.try putting the heater on recirc,see if they warm up quicker.
air lock/bad flow in rad,pump failure,all would show an increase in temps.

[Darkstar]

sorry
yes its a diesel, had it 6 months now,
got up to temp fairly quickly during summer as far as i can remember
antifreeze strength ok down to -17
no problems with water loss and radiator looks ok, cant tell age looks clean

[mikexgough]

Strange symptoms...... my diesel at yesterdays -1 early 2c during the day.....went 4 miles to get to normal temp (Mason modded gauge), obviously when the engine stopped it cooled very quickly due to the ambient temperature......
I wonder if indeed your thermostat is open or you actually have one installed....... only one way to find out.....that is open it up...

[BongoMTBer]

I suspect thermostat stuck open allowing flow to the radiator from cold. If you are getting full circulation through the rad, on a cold day, you are unlikely to ever reach running temp. It shouldn't start to open until the high 80's and then it should modulate to control coolant at that temp.

I would be changing mine with your symtoms.

[widdowson2008]

From your description, this is exactly what would happen if your thermostat is stuck open. Engine not getting a chance to warm up properly.
Where is your TM-2 sensor located?

Not quite true BongoMTBer. Stat actually begins to open in the LOW 80's (82/84). But I agree totally with everything else you say.

[mikexgough]

From your description, this is exactly what would happen if your thermostat is stuck open. Engine not getting a chance to warm up properly.
Where is your TM-2 sensor located?

Not quite true BongoMTBer. Stat actually begins to open in the LOW 80's (82/84). But I agree totally with everything else you say.

82 is the spec Tama make 'em to.....

[Darkstar]

From your description, this is exactly what would happen if your thermostat is stuck open. Engine not getting a chance to warm up properly.
Where is your TM-2 sensor located?

Not quite true BongoMTBer. Stat actually begins to open in the LOW 80's (82/84). But I agree totally with everything else you say.

TM-2 mounted on engine head as per fitting instructions from Haydn

looks like a new stat then, cant chance it deciding to close and staying close

[widdowson2008]

Best option IMHO. If the stat IS stuck open, then your engine will not reach ideal running temp and until it does it's bloody inefficient - less mpg.
AND, as you say, if the stat isn't working correctly, I suppose there is a risk that it could close and stay closed and that could have a disaterous effect - engine overheat.

[skater]

Get a genuine Mazda one.

I had mine changed as part of bigger job just for peace of mind ( new rad etc anyway ).
The mechanic showed me the old one, it had rub marks on middle " bit " .
I assume some sticking was starting to happen.

Don't know if old one was Mazda or not.

James.

[widdowson2008]

Get a genuine Mazda one.Definitely IMHO
The mechanic showed me the old one, it had rub marks on middle " bit " .
I assume some sticking was starting to happen. Rub marks are normal (and acceptable). Its caused when the inner bronze bit moves within the cage. (VERY tight tolerance between the two, and NEEDS to be.)

Don't know if old one was Mazda or not.The main difference between a genuine Mazda stat and a non Mazda is that the genuine Mazda has a rubber seal around the fixed steel stem (Blueprint)

James.

[Darkstar]

Rang Steve at outback autos he's going to have a look next week,

he 'll do an engine flush and coolant change at the same time, hopefully there is a thermostat in place as otherwise could point to a other hidden problem,

but as i did a 300mile drive in the summer and had no problems i think there will be one.


thanks all for your ideas

[Northern Bongolow]

if its stuck open,and you need the motor,try giving the stat housing a few sharp taps(dont break it in this cold weather.)the spring pressure should close it.but then watch the temps like a hawk ,in case it sticks shut.
usuall not my fault if it blows up disclaimers apply

[The Great Pretender]

And to state the obvious, use your data logger to test the stat.
Your 5 lil pinkies wrapped around the return from the rad as the engine is warming up but not hot will let you know if the stat is stuck open.