Car running very slightly hotter, why?

[ClareQuilty]

I always keep a very close eye on the engine temperature when driving in Thailand - in this brutal climate it seems the number one car-killer. A couple weeks ago my Peugeot developed a fluctuating temp - about 90° around town but still the normal 72° on the highway. Turned out to be one of the two radiator fans & was quickly fixed for a few hundred baht.

 

Now the car's temp no longer fluctuates, but city or highway, air on or off, it holds at 79°. Now - my question is, why didn't the fix return the running temp to 72°? The thermostat wasn't changed, so why the change in temp? Any advice?

[stubuzz]

Was the fan fixed correctly or was some sort of bypass/bodge done?

[Denim]

Maybe fan works but not as fast as before. Or  temperature sensor on new fan set differently to old sensor ?

 

[Pdaz]

Check that a plastic bag or some other road debris isn't blocking the front of the radiator. 

[NanLaew]

5 hours ago, ClareQuilty said:

Turned out to be one of the two radiator fans & was quickly fixed for a few hundred baht.

...is probably the reason.

 

How old is the Peugeot anyway?

[ben2talk]

27 minutes ago, NanLaew said:

...is probably the reason.

 

How old is the Peugeot anyway?

1991 Peugot 405

 

We're talking a seriously loved bucket here. Good luck with it! I had a soft spot for the Peugot 406 when I had my 306 turbo back in the day. The 2.0 turbo was a real go-kart, went around greasy roundabouts in the rain faster than the standard 306 could do it in the dry.

 

Edited July 2, 2017 by ben2talk

[ClareQuilty]

17 hours ago, NanLaew said:

...is probably the reason.

 

How old is the Peugeot anyway?

Nonsense. It was cheap because it was the connection, nothing to it. I asked him to set both fans running continuously, just like before. The age of the car has little relevance to running hot, but it's a 1997.

 

The fan speed or fan temp sensor couldn't be the issue because as I said the car runs the same temp on the highway as in town driving.

 

No plastic bag in other obstruction. 

[tonray]

Check your coolant levels , losing without any apparent leakage ? When you turn on the heat (yes you need to do this) do you smell coolant ? Upon Visual inspection, do you see oil in coolant....if yes to any of these...maybe head gasket leak.

[bontang]

14 minutes ago, tonray said:

Check your coolant levels , losing without any apparent leakage ? When you turn on the heat (yes you need to do this) do you smell coolant ? Upon Visual inspection, do you see oil in coolant....if yes to any of these...maybe head gasket leak.

Yeah Old Bomb however if it has being reliable Love of your Life, Check if the Cooling Fans are running in the right direction 

Have you removed the Radiator cap when the engine is cold & then start the Engine

you can see if there is any serious movement in  the Coolant in the radiator you may have to let the Engine warm up to for a few Minuets  this will tell you if there Emission leakage, (head gasket)

When the engine gets HOT have you checked the Temp between Top Radiator Hose & the Bottom Hose

Speck is 8dgs difference,  you could have circulating issue i.e blocked Radiator,  Regulator not operating properly or Water pump impellor issue,

Good luck

 

[iang]

The wiring to there replacement fan could be connected the wrong way around. I.e. the fan is blowing instead of sucking, or sucking instead of blowing- depending on whether the fan use in front of our behind the radiator!

[ClareQuilty]

The fan wrong way round sounds like a good suggestion, especially given that's what they were just recently fiddling with (usually it takes 2-3 tries to get something done right here.

 

As for the coolant in the radiator & overflow tank, yeah of course I checked that - first thing I did. Full like always.

[Foozool]

In highway radiator cools down by getting airflow, but on streets fan only cools down.

It could be sensor that kicks on higher temp. It could be aftermarket part (fan sensor). Get an OEM. 

Edited July 4, 2017 by Foozool

[ClareQuilty]

1 hour ago, Foozool said:

In highway radiator cools down by getting airflow, but on streets fan only cools down.

It could be sensor that kicks on higher temp. It could be aftermarket part (fan sensor). Get an OEM. 

Yes the temperature is exactly the same on the highway or driving around town.

[1FinickyOne]

Did you go to the Peugeot dealer?

 

I have found that though it might be more expensive than some shop, there is nothing as good as going into the dealer... 

[paddyjoe41]

CHECK TO SEE IF THE RAD CAP VENT HOLE MAY BE PARTIALLY BLOCKED,BIT OF RUST WATER UNDENEATH OR SOMETHING SMALL JUST SLIGHTLY BLOCKING THE RELEASE.MAYBE NEED TO FLUSH OUT THE RAD,SOMETHING SMALL ARE MY THOUGHTS.GOOD LUCK.

Edited July 5, 2017 by paddyjoe41

[transam]

Does sound like the stat though as the engine temp stays constant. There will be times when the engine gets all the cooling it wants so the temp would drop to the 72 you say the stock stat is. Are you sure the stock stat is 72...?

 

[transam]

Just done a bit of research and it seems the old ride has an 80 stat......If so you are near spot on...

[bazza73]

The proposition that the thermostat is accurate has some flaws. It depends on when and how it was calibrated.

Check the workshop manual for the recommended operating temperature.

If the temperature gauge is showing the same temperature for city and country driving, I wouldn't worry. It means the cooling system is doing what it is supposed to.

Measuring in terms of 72 and 79 degrees is daft. The temperature gauges in most vehicles are only repeatable to + or - 5 degrees.

[VocalNeal]

One of the fans is for the cooling the other is for the AC.  90 is OK as is 79. But yes check the fan direction! 

 

 

[jacko45k]

72 or 79, both seem to be on the cool side.

I see you have set both fans to run when usually one kicks in and out as required.

 

Perhaps as someone was recently fiddling with it something has changed slightly, but is it really something to worry about?

[Mattd]

8 minutes ago, jacko45k said:

72 or 79, both seem to be on the cool side.

I'd say very much so, the whole purpose of having a pressurised cooling system is to allow the temperature to be hot, the hotter the better up to a point, obviously too hot is detrimental, but so is too cold, by pressurising the system the water can go to over 100 degrees C.

The thermostat is only there to allow the engine to warm up quickly, it is not there to regulate the temperature, all it does is stop the flow of water until the coolant reaches the set point temperature of the thermostat.

The whole design criteria of the engine will be based around an optimal running temperature to allow the differing metals to get to the correct clearances.

In Thailand there isn't a great deal of advantage in having a Thermostat, as the ambient temperature is never that cold and it is one more bit to fail.

[transam]

4 minutes ago, Mattd said:

I'd say very much so, the whole purpose of having a pressurised cooling system is to allow the temperature to be hot, the hotter the better up to a point, obviously too hot is detrimental, but so is too cold, by pressurising the system the water can go to over 100 degrees C.

The thermostat is only there to allow the engine to warm up quickly, it is not there to regulate the temperature, all it does is stop the flow of water until the coolant reaches the set point temperature of the thermostat.

The whole design criteria of the engine will be based around an optimal running temperature to allow the differing metals to get to the correct clearances.

In Thailand there isn't a great deal of advantage in having a Thermostat, as the ambient temperature is never that cold and it is one more bit to fail.

Rubbish......

 

[KNJ]

Fan problems, inconsistent, did they clean or replace the fan, with OEM  or from Somchais bin of parts.

Fans are mechanical and have bearings, ..........just a thought

[Mattd]

10 minutes ago, transam said:

Rubbish......

 

And why do you say that? A cooling system thermostat in a cold country makes perfect sense, however here once the coolant is at operating temperature then it will be fully open and therefore cannot regulate the temperature anymore, in Thailand the ambient temperatures mean that the engine or coolant never really get that cold, making the thermostat pretty much redundant after a few minutes.

The airflow over the radiator is the only way of keeping the temperature of the water consistently cool (regulated), cooling fans today are thermostatically controlled to give better cooling regulation, so would not be perhaps running when the car is blatting down the motorway, but would be full blast when the car is going slowly etc.

As the coolant expands due to the heat, so does the pressure in the system, hence the expansion tanks now seen.

The increase in temperature could only be caused by a difference in airflow across the cooling radiator, or a change in the ignition timing etc. (which is near impossible nowadays).

 

[transam]

1 minute ago, Mattd said:

And why do you say that? A cooling system thermostat in a cold country makes perfect sense, however here once the coolant is at operating temperature then it will be fully open and therefore cannot regulate the temperature anymore, in Thailand the ambient temperatures mean that the engine or coolant never really get that cold, making the thermostat pretty much redundant after a few minutes.

The airflow over the radiator is the only way of keeping the temperature of the water consistently cool (regulated), cooling fans today are thermostatically controlled to give better cooling regulation, so would not be perhaps running when the car is blatting down the motorway, but would be full blast when the car is going slowly etc.

As the coolant expands due to the heat, so does the pressure in the system, hence the expansion tanks now seen.

The increase in temperature could only be caused by a difference in airflow across the cooling radiator, or a change in the ignition timing etc. (which is near impossible nowadays).

 

I don't think you understand what a stat does in relation to an engines  temp requirement or the cooling system installed...

Tell me why different engines have different running temps controlled by a stat which open and shut at that engines temp requirement...?

[Mattd]

1 hour ago, transam said:

I don't think you understand what a stat does in relation to an engines  temp requirement or the cooling system installed...

Tell me why different engines have different running temps controlled by a stat which open and shut at that engines temp requirement...?

I fully understand what a stat does, 100%, I am a fully qualified marine engineer, so do have some background!

Different engines will have different optimal temperatures, hence the need for differing stat opening temperatures, this will be determined by the manufacturer of the engine, the whole reason that engines are built with 'loose' tolerances when cold is that when the engine reaches the optimal temperature these tolerances are now correct, hence why there are tappet clearances on an OHV type engine, or cam to bucket clearances, piston ring gags, big end bearings have a clearance etc. etc. if they were a close fit to start with, then the engine would seize when at temperature.

In a cold climate then yes, I would agree that the stat has a big part to play in the coolant (and therefore engine) temperature regulation, if it was in Siberia, then it would be critical, otherwise the engine could not get to the correct temperature, we are not in a cool climate, so the game changes quite a lot. 

When I was offshore, we used to operate a lot in SE Asia and removed the Amot valves (stats) to improve the cooling water flow, along with increasing the size of the plate coolers for the heat exchange, this was the ONLY way to keep the temperatures down, another vessel had keel coolers, which work fine in cooler sea water temperatures and when the vessel was moving, not so when the sea temperatures increased and / or the vessel was stationary, as the heat exchange could not happen and therefore overheating would occur, nothing to do with any stats, only do with an exchange of heat to dissipate the heat built up in the cooling water.

Whilst, conversely, in cold sea water areas, the Amot valves were critical and we would even partially close valves to keep the temperatures.

 

The cooling of an engine is all about the flow of a cool liquid around the engine, if the engine temperature increases, then the causes can be no or slower flow of the coolant, so the water pump deficient, a blockage in the water jacket, radiator or hoses, a failed closed stat (that should not happen with a wax type), or the exchange of heat is not correct, so in the case of a water cooled car engine the flow of air over the radiator.

It is unlikely that the stat would be causing this in this instance, given the fan issue prior.

Once running, it would be extremely rare for an engine to be operating at a lower than optimal temperature in this climate.

Edited July 5, 2017 by Mattd

[transam]

2 minutes ago, Mattd said:

I fully understand what a stat does, 100%, I am a fully qualified marine engineer, so do have some background!

Different engines will have different optimal temperatures, hence the need differing stat opening temperatures, this will be determined by the manufacturer of the engine, the whole reason that engines are built with 'loose' tolerances when cold is that when the engine reaches the optimal temperature these tolerances are now correct, hence why there are tappet clearances on an OHV type engine, or cam to bucket clearances, piston ring gags, big end bearings have a clearance etc. etc. if they were a close fit to start with, then the engine would seize when at temperature.

In a cold climate then yes, I would agree that the stat has a big part to play in the coolant (and therefore engine) temperature regulation, if it was in Siberia, then it would be critical, otherwise the engine could not get to the correct temperature, we are not in a cool climate, so the game changes quite a lot. 

When I was offshore, we used to operate a lot in SE Asia and removed the Amot valves (stats) to improve the cooling water flow, along with increasing the size of the plate coolers for the heat exchange, this was the ONLY way to keep the temperatures down, another vessel had keel coolers, which work fine in cooler sea water temperatures and when the vessel was moving, not so when the sea temperatures increased and / or the vessel was stationary, as the heat exchange could not happen and therefore overheating would occur, nothing to do with any stats, only do with an exchange of heat to dissipate the heat built up in the cooling water.

Whilst, conversely, in cold sea water areas, the Amot valves were critical and we would even partially close valves to keep the temperatures.

 

The cooling of an engine is all about the flow of a cool liquid around the engine, if the engine temperature increases, then the causes can be no or slower flow of the coolant, so the water pump deficient, a blockage in the water jacket, radiator or hoses, a failed closed stat (that should not happen with a wax type), or the exchange of heat is not correct, so in the case of a water cooled car engine the flow of air over the radiator.

It is unlikely that the stat would be causing this in this instance, given the fan issue prior.

Once running, it would be extremely rare for an engine to be operating at a lower than optimal temperature in this climate.

You ain't on a boat............

[Mattd]

Just now, transam said:

You ain't on a boat............

Exactly the same principles apply.

[transam]

Just now, Mattd said:

Exactly the same principles apply.

A stat is fitted to a road car engine set at a temp that ride needs to operate at optimum performance and protection, that's why rides can have a different stat temp...YOU stated don't need a a stat in LOS cos it's warm which is total misinformation..

[Mattd]

Just now, transam said:

A stat is fitted to a road car engine set at a temp that ride needs to operate at optimum performance and protection, that's why rides can have a different stat temp...YOU stated don't need a a stat in LOS cos it's warm which is total misinformation..

We will have to agree to disagree, the engine coolant temperature can and often will be hotter than the stat opening temperature, as once open it can do no more, it's job is done, the rest is up to the exchange of heat, i.e. airflow and coolant flow.

In Thailand the engine would get up to operating temperature quite quickly without a stat, I am certainly not saying you should operate without one, just that you could, try it in a cold climate and that would cause issues due to operating temperature possibly being too low in circumstances, that ain't happening here.

The protection of the engine temperature wise is the PRV to the expansion tank and the the operator monitoring the temperature gauge. Trust me, if the airflow or coolant flow is restricted in anyway, then the engine will overheat with or without the stat.