Car Temperature fluctuating from 90--> 70 when driving? What could it be?? and also..

Danny_G

Car is Peugeot 406 SALOON 2000, petrol.


[See picture attached]



When driving around, letting the engine get heated the temp gauge it is usually on 90, constantly.

Recently when driving, for 30minutes+ it has recently started to go to 80,

and then back up to 90.

It went to 70 too.


Other things noticed.

* Oil is Not milky

* Exhaust shows no fluid coming out, and is clear, odorless

* No white smoke

* Sometimes water escapes the coolant cap

* Petrol seems to be burning more quicker

*No milky oil

*Radiator has recently been replaced so is new.

* Cambelt/ water pump has recently been replaced

* Petrol burning quicker!
(the level on the petrol gauge seems to be getting less at a quicker pace - burning petrol quicker)

1) Is 90 degrees a common temperature for the car to be at, while driving? (which it is, it is on 90 often)

2) What does it sound like, from all the symptoms I have presented?


3) after a long drive, with the engine still on, When parked idle,

..... then going to the back of the car, and smelling the exhaust pipe, it doesn't smell of anything. Is this normal? Shouldn't it smell of petrol? (it is visibly clear, no smoke)

See picture attached.

Thanks everybody,

patman99

Air lock in water system maybe?.
Try the following -

Take cap off expansion bottle,
Start engine and let it run up to temperature,
When cooling fan kicks-in turn heating to maximum, open all vents and turn blower on full.

Watch the expansion bottle to see if any bubbles appear as temperature rises again. If there are bubbles, keep engine running/heater on until bubbles stop.
Turn off engine, allow to cool, then top up fluid in expansio tank before replacing cap.

BeenThroughItAll

I'd go for either the water pump has failed (having been replaced recently, you might think not likely, but I bet it was a cheap aftermarket pump used and they can be utter crap), or more likely that the thermostat has failed and the engine temperature isn't being properly maintained.

Or, third possibility, the coolant temperature sender might be on its way out - I don't know the engine so it may be that the ECU and clocks share a single CTS, in which case the ECU won't get fuelling right, potentially causing lower MPG, and the dash won't display the temperature correctly.

And 90degC is a perfectly sensible engine temperature. I'd expect that gauge to sit bang in the middle under normal use.

For reference, the thermostat on my wife's petrol Audi is rated at 87degC and live mapping data shows the coolant generally is around 88-91degC once fully up to temperature.

Danny_G

patman99 wrote: »

Air lock in water system maybe?.
Try the following -

Take cap off expansion bottle,
Start engine and let it run up to temperature,
When cooling fan kicks-in turn heating to maximum, open all vents and turn blower on full.

Watch the expansion bottle to see if any bubbles appear as temperature rises again. If there are bubbles, keep engine running/heater on until bubbles stop.
Turn off engine, allow to cool, then top up fluid in expansio tank before replacing cap.

Thanks.

Using your suggestion, as the cap will be Open (to let bubbles escape) will that let more are to enter, through the hole, and enter into circulation?

creating more air to enter the system?


how about the engine water taps/screws (which connect to the radiator pipe entering the internal heating system) and are sometimes used to bleed air/the system? should they be opened, and at what point

BeenThroughItAll

Hang on, is this the same car which loses half a pint of coolant overnight?

Have you fixed that problem yet?

It sounds like you need to employ the services of a diagnostician rather than blindly fumbling about in the dark.

Your dodgy temperature readings could all be down to the fact there's not enough bloody coolant in the thing.

Danny_G

patman99 wrote: »

Air lock in water system maybe?.
Try the following -

Take cap off expansion bottle,
Start engine and let it run up to temperature,
When cooling fan kicks-in turn heating to maximum, open all vents and turn blower on full.

Watch the expansion bottle to see if any bubbles appear as temperature rises again. If there are bubbles, keep engine running/heater on until bubbles stop.
Turn off engine, allow to cool, then top up fluid in expansio tank before replacing cap.

Thanks.

Using your suggestion, as the cap will be Open (to let bubbles escape) will that let more are to enter, through the hole, and enter into circulation?

creating more air to enter the system?


how about the Bleeding tap - engine water taps/screws (which connect to the radiator pipe entering the internal heating system) and are sometimes used to bleed air/the system?
should they be opened, and at what point, whilst doing your instructions ?

Danny_G

BeenThroughItAll wrote: »

Hang on, is this the same car which loses half a pint of coolant overnight?

Have you fixed that problem yet?

It sounds like you need to employ the services of a diagnostician rather than blindly fumbling about in the dark.

Your dodgy temperature readings could all be down to the fact there's not enough bloody coolant in the thing.

Yes coolant was put into the system, so it has been driving with coolant into it.

BeenThroughItAll

Danny_G wrote: »

Yes coolant was put into the system, so it has been driving with coolant into it.

Yes, but if you're losing enough coolant to need to top it up often, it's entirely possible that the level is dropping during use.

I have not had to 'top up' coolant in any cars I've owned in the last three years and ~100K miles of use, except my wife's Audi when it had a leaking coolant flange, and that lost about 100ml in the course of a month.

Danny_G

Would the temperature between 70-90 be a normal thing?

(as the marks on those points are thicker,
so the temperature between them points would be fine?

or it seems abnormal, and can indicate something?

forgotmyname

No its not normal. There is a lack of coolant in the engine.

oops no water ahh found some no its gone again.... As soon as you have a drive on a hot day your going to be back saying it boiled over and water came out everywhere.

Dont drive it get a garage to collect it and fix it.

BeenThroughItAll

Danny_G wrote: »

Would the temperature between 70-90 be a normal thing?

(as the marks on those points are thicker,
so the temperature between them points would be fine?

or it seems abnormal, and can indicate something?

Did you even bother to read my post (hint: number 3)? If you can't be arsed to read the answers I'll not bother replying any more.