Engine temp oddity

[KarlD]

Evening gents. I have recently purchased a lovely 2010 RCZ 156 GT and it already has me scratching my head

On starting and idling there are no bubbles in the expansion tank.

The engine pulls and sounds fine, no mayo under the oil filler cap. No white smoke.

Sat idling the temp gauge will go up to 90 and sit there perfectly normally. No heat out of the vents.

When moving the temp gauge goes steadily down and will either stay at rock bottom or hover around rock bottom. No heat out of the vents.

On turning the car off and checking the radiator pipes both top and bottom are equally warm/hot.

On start up I get the engine fault needs service message every time, which I hope is related.

This sounds like a dodgy heater matrix, thermostat or temp sensor right…or all three of them?

Confusion is that I do not understand how both top and bottom radiator pipes can be warm/hot and still not get any heat out of the vents?!

Any ideas guys?

Thanks in advance
Karl

 

[Pedro]

Matrix could be knackered?
Temp gauge fault is normally the sensor also the Thermostat tank housing the sensor are a known generic failure on all the variants

 

[KarlD]

Thanks Pedro. Before posting I did have a thorough search through the site and the wider web so as you say these are likely culprits. Fingers crossed it’s not a hg. The car is off to the garage tomorrow so I’ll update the thread when I know more

 

[KarlD]

Right I can finally update. The garage found grease like substance was blocking the thermostat housing so they drained the coolant, ran a flush through and then fitted a new thermostat housing.

Ran the car and when driving it’s fine, but on idle the hot air quits and the temp gauge goes cold again. They drained the coolant and looked at the pipes that feed coolant to the turbo and there was still some of the grease like substance in the pipes.

Changed the coolant again, checked the matrix and that has evidence of the grease there also. They think a previous owner put something in to deal with a problem, maybe blown hg.

They think I should collect the car and run it for a couple of weeks to get everything moving, which I’m inclined to do. Then take the car back for head off and check and if all looks ‘ok’ get new hg, matrix, timing chain and pulleys etc.

Any idea what the grease might be and why it’s present in such quantity. Other than the issues I describe in my first post the car drives lovely.

TIA

 

[Pedro]

Possibly Radweld or another stronger gasket sealer as per garage usually used to stop a leaking HG or a severe coolant leak like the tank etc

 

[KarlD]

That was my thought and that of the garage doing the work. Doesn’t bode particularly well for the engine does it…

 

[boatdriver]

I have the same problem. The temerature gauge has always gone up to 90 and stayed there, now it nearly gets to 90 and speed aand as soon as I slow down the needle drops to 80 then 70. No loss of coolant and the top radiator pipe gets warm and the botton stays cold. When I turn the engine off after a run I can hear a hissing sound from where the thermostat is situated.
I had a new up rated thermostat housing fitted a bout a year ago I get heat through the air vents but its not exactly hot air.
Going into the garage week after next under extended warrenty.

 

[Hrendous]

I have the same problem. The temerature gauge has always gone up to 90 and stayed there, now it nearly gets to 90 and speed aand as soon as I slow down the needle drops to 80 then 70. No loss of coolant and the top radiator pipe gets warm and the botton stays cold. When I turn the engine off after a run I can hear a hissing sound from where the thermostat is situated.
I had a new up rated thermostat housing fitted a bout a year ago I get heat through the air vents but its not exactly hot air.
Going into the garage week after next under extended warrenty.

Hi Boatdriver, I see your post is a few years old however thought it be a long shot to see if your still on this forum. Having similar problems, have just changed the Thermostat Housing to no avail. Next step is to change the Heater Matrix. Did you end up fixing the issue with a new Heater Matrix?

 

[Pedro]

You may have an air lock? One way to check is let the car heat up with the expansion cap off & the heater blower full on any air trapped in the system should bubble up in the bottle
Possibly other issues could be the matrix these get full of dirt & can corrode yours may have residues from the additive which was previously used in the coolant?
You must completely flush out the cooling system after any fault issues & take steps as above to release any air which ahs entered after any work is completed

 

[Hrendous]

You may have an air lock? One way to check is let the car heat up with the expansion cap off & the heater blower full on any air trapped in the system should bubble up in the bottle
Possibly other issues could be the matrix these get full of dirt & can corrode yours may have residues from the additive which was previously used in the coolant?
You must completely flush out the cooling system after any fault issues & take steps as above to release any air which ahs entered after any work is completed

Hi Pedro,

I have gone down the road of bleeding the system to remove air locks a few times. Drained both points, first at the Thermostat Housing and second the bleed port located on the output to the heater matrix on at the firewall.

I can’t find a description of operation on how the thermostat housing electrical system works. You have a temp sensor located forward of the housing. The second connector located aft appears to control the heater matrix flow? Or is it a position sensor? On the vehicle side, Voltage readings open circuit with no load is 12V DC with a raise in voltage to 14V above 1600rpm. I believe this sensor goes to the climate control module in the cabin but cant be sure. Need to have another look at the wiring schematics.

If anyone can shed some light on the description/operation of this it would be greatly appreciated.

 

[Pedro]

Last time I had someone bring a car with that fault it was the thermostat sticking open?
One owner on here fitted a brand new tank & the thermostat was u/s plus if you fit the wrong tank it will throw up all sorts of issues as others have found out so its imperative you match the exact OEM part numbers to your engine code

 

[Hrendous]

Last time I had someone bring a car with that fault it was the thermostat sticking open?
One owner on here fitted a brand new tank & the thermostat was u/s plus if you fit the wrong tank it will throw up all sorts of issues as others have found out so its imperative you match the exact OEM part numbers to your engine

One owner on here fitted a brand new tank & the thermostat was u/s plus if you fit the wrong tank it will throw up all sorts of issues as others have found out so its imperative you match the exact OEM part numbers to your engine code

Thanks Pedro for the info. Yes you need to be ware there are different thermostats available. I purchased the OEM unit from Peugeot. Mine was the new type so it was a like for like replacement.

It seems I got a bum steer from the previous owner who failed to mention the heating issue. I was more fixated at at forward of the firewall as the car had recent engine work requiring its removal and installation.

It was summer when we purchased the car so the heater seemed oEven though I flushed the heater matrix and it appeared to flow at a satisfactory rate it was a new heater matrix that has fixed the issue.

When comparing both new and old matrix heaters once it was out of the car the flow was completely unobstructed on the new unit.

Finally warm car for our brutal Aussie winters….

Now to my next issue…Burst tyre warnings going off on the instrument cluster like a dog shot in the proverbial.

 

[Pedro]

These can be down to wheel speed sensors ABS/ESP sensors/ wiring fault or possibly a BSI reset? You need a scan to check if the ECU has triggered any fault codes which may have been historically stored previously after a similar issue the other one to watch out for if fitted is the TPMS system which thankfully I don't have on my 200
Good luck & let us know how the fault was fixed