Temp gauge suspicious

[Aleskoda]

Morning guys,

 

just drove I’ve to work in my SDI. Each trip is around 20 min or so. Today I’ve noticed my temp gauge reaching middle, then drop then go back up. Could this be standing in traffic 5 min and a combination of having heaters on full? Only noticed about a 5 mile drop on MPG but it is 3 degrees 

 

cheers  

[JWvrs25]

Needs a new thermostat

[KenONeill]

@Aleskoda - Yes: the interior heater uses the same engine "waste" heat as goes to the radiator and is reported by the gauge.

[Breezy_Pete]

Sounds normal in the circumstances.

[JWvrs25]

Maybe the SDI is different, but i had same issue in my TDI, also happened cruising gently on motorway, gauge would drop slightly. Turns out thermostat was stuck and once changed it will now come up to temp and stay there even when heaters are on etc.

 

[bmbmdmb]

Diesels are thermally efficient (don't produce a lot of waste heat).

 

From experience (with a 1.9TDi vrs) engine coolant had reached 90C after 3 miles. Car was idling in car park and heater switched on (about 2 on full heat). 

Exterior temperature was around 0-5C 

The coolant temperature started to fall.

 

I have never had this happen on a drive with the heater blowers on, however.  I suspect the thermostat is on its way out, like JW suggested, if you have never had this happen before.

[Aleskoda]

Thanks guys, I will see how it is on way home today. I’m assuming a thermostat change is difficult? 

 

I will let you know how I go on the way home. Is there a risk that the engine could over heat, I’ll just take it slow on the way back incase? 

[Breezy_Pete]

40 minutes ago, bmbmdmb said:

Car was idling in car park and heater switched on (about 2 on full heat). 

Exterior temperature was around 0-5C 

The coolant temperature started to fall.

 

I have never had this happen on a drive with the heater blowers on, however

 

The OP can maybe confirm, but I read it as he drove a little way, the temp got to 90C, then he sat in traffic for 5 mins (idling, more or less, presumably) with the blowers on full, and the temp dropped a little. That seems entirely reasonable to me, and not really any different to what you saw in your car park?

 

38 minutes ago, Aleskoda said:

I’m assuming a thermostat change is difficult?

 

Not really.

[KenONeill]

Well, OK this is a TDi, but even so...

 

A few weeks ago it snowed, and the drive in to work was slower than usual, with the turbo mostly "off". The engine never quite got up to temperature. On the way back the snow had melted, and the engine came up to temperature and stayed there, running on boost but never above peak torque.

[Aleskoda]

Seemed alright on the way home, must have just been low outside temp. I’ll keep an eye on it 

 

cheers guys 

[Chris Berry]

It may not be the thermostat; it may be the Coolant Temp Sensor. This is what I had to replace on mine.

 

My symptoms were that the temp needle was going up, then straight back down (as if engine wasn’t on) then up again; basically, having a little dance around!! If yours does this, then it’s more likely it’s the Sensor & not the thermostat.

Edited 1 February, 2018 by Chris Berry

[stuart vrs]

My vrs has recently started this, the temp goes upto 90 then starts falling abit then back up to 90. Is it easier to change the whole coolant bottle or the coolant temp sensor I've got a price of £10 for the sensor from TPS. 

 

[JWvrs25]

16 minutes ago, stuart vrs said:

My vrs has recently started this, the temp goes upto 90 then starts falling abit then back up to 90. Is it easier to change the whole coolant bottle or the coolant temp sensor I've got a price of £10 for the sensor from TPS. 

 

The coolant bottle sensor is a level sensor, the temp sensor is on the right hand side of the block in a plastic housing. 

Its fairly easy to change although make sure you buy new coolant as you will loose alot.

Drain the tank first then remove sensor and have something to soak up coolant that leaks

[bmbmdmb]

Do you have an update? Replace any parts?

[rum4mo]

21 hours ago, stuart vrs said:

My vrs has recently started this, the temp goes upto 90 then starts falling abit then back up to 90. Is it easier to change the whole coolant bottle or the coolant temp sensor I've got a price of £10 for the sensor from TPS. 

 

 

As said earlier, ie forget the tank with its level sensor, but as I don't like having problems, I tend to order in a new O-ring seal and plastic retainer, just in case the old O-ring seal has aged and the plastic clip flies away into an unknown location - it is black so losing it might be easy.

[JWvrs25]

1 hour ago, rum4mo said:

 

As said earlier, ie forget the tank with its level sensor, but as I don't like having problems, I tend to order in a new O-ring seal and plastic retainer, just in case the old O-ring seal has aged and the plastic clip flies away into an unknown location - it is black so losing it might be easy.

Most sensors come with the O ring, sensible to get the clip ordered although if your careful its possible to remove without it pinging off. It cant go that far even if it does but saves spending the rest of the day fishing around the back of the subframe where all these bits seem to 'collect' 

[Aleskoda]

Hi guys,  no issues I think it may be just the outside temp and sitting in traffic combined together. No parts replaced, just done the rear shoes and new release springs nice to have a handbrake that means I don’t roll down a hill

[rum4mo]

18 hours ago, JWvrs25 said:

Most sensors come with the O ring, sensible to get the clip ordered although if your careful its possible to remove without it pinging off. It cant go that far even if it does but saves spending the rest of the day fishing around the back of the subframe where all these bits seem to 'collect' 

 

I was meaning if the main dealer was used as a source for the new sensor.

 

Buying a new clip, I learned the hard way years ago when I was refurbishing the auto adjuster on wife's old Fiesta clutch cable/pedal, the extremely strong clip flew off and disappeared down behind the bulkhead sound proofing, I had to fit a Jubilee clip to get the car ready for the next day.  After that I bought 2 new clips and tied a length of dacron lacing to the next clip, it went on without any drama, still got the spare clip maybe 20 years later! I had done that job a few times before on other cars without that problem!

[TMB]

5 hours ago, rum4mo said:

 

I was meaning if the main dealer was used as a source for the new sensor.

 

Buying a new clip, I learned the hard way years ago when I was refurbishing the auto adjuster on wife's old Fiesta clutch cable/pedal, the extremely strong clip flew off and disappeared down behind the bulkhead sound proofing, I had to fit a Jubilee clip to get the car ready for the next day.  After that I bought 2 new clips and tied a length of dacron lacing to the next clip, it went on without any drama, still got the spare clip maybe 20 years later! I had done that job a few times before on other cars without that problem!

 

I had a Fiesta too. I remember laying on my back with my head under the dash to replace the auto clutch cable adjuster. Haha

[KenONeill]

On 2/3/2018 at 19:15, Aleskoda said:

Hi guys,  no issues I think it may be just the outside temp and sitting in traffic combined together. No parts replaced, just done the rear shoes and new release springs nice to have a handbrake that means I don’t roll down a hill

Yeah; that's the combined point of my earlier posts is that this time of year it may just be the weather.

[Aleskoda]

Hi guys, 

 

could this his problem be leading to poor fuel economy or could it still be weather related ... temp gauge seems a little different to normal just done my 25 min commute and temp reached optimal temp then after a bit of city driving it has began to drop 

[Aleskoda]

Just now, Aleskoda said:

Hi guys, 

 

could this his problem be leading to poor fuel economy or could it still be weather related ... temp gauge seems a little different to normal just done my 25 min commute and temp reached optimal temp then after a bit of city driving it has began to drop 

Just done 43.6 MPG ... a like 10-15 lower than normal 

[JWvrs25]

try changing the coolant sensor first, sounds like it could be dodgy causing the car to think its cold. Would advise thermostat change as well as the original will be a bit past it best by now

[LB123]

Seems to be a number of posters thinking it's just the very cold for UK weather were having. Do you remember the olden days when cars wore radiator muffs in winter? Overcooling of the water in the rad despite the stat. Theory was that when it's very cold the water in the rad can get down into single figures, especially with a diesel and an SDI doesn't make much heat. The stat opens, a big slug of cold water enters the pipes, makes it way through the engine before hitting the stat and causing it to close again. Maybe stats were more open/closed digital rather than linear/analogue in the olden days but it was a common trick.

A trial of partially blanking off say 1/3 of the rad while the weather is so cold might restore your comfort and peace of mind.

[Aleskoda]

7 hours ago, LB123 said:

Seems to be a number of posters thinking it's just the very cold for UK weather were having. Do you remember the olden days when cars wore radiator muffs in winter? Overcooling of the water in the rad despite the stat. Theory was that when it's very cold the water in the rad can get down into single figures, especially with a diesel and an SDI doesn't make much heat. The stat opens, a big slug of cold water enters the pipes, makes it way through the engine before hitting the stat and causing it to close again. Maybe stats were more open/closed digital rather than linear/analogue in the olden days but it was a common trick.

A trial of partially blanking off say 1/3 of the rad while the weather is so cold might restore your comfort and peace of mind.

So maybe a sheet of cardboard infront of it overnight?