Nasty Overheating habit

[reallyloud]

My 106 Rallye has never given me anything to complain about over the 9 years I've owned it, but its been overheating recently and I'm struggling to find out why.

 

Originally it got up to 3/4 temperature - fan kicks in and it would pretty much remain at that temperature. The faster I went the quicker it would reach the 3/4 mark obviously - when I'd slow down/release the throttle and coast the temperature gauge stablilzes.

 

So after replacing the radiator, several pipes, thermostat, checking the head gasket (garage tested and told me its fine) as well as renewing the coolant (which has always been the same colour as it came from the bottle) as well as checking the water pump (after a recent cam belt change) its still going off the scale. Things have got worse now, as the fan switch has stopped working, meaning it now overheats even when idling with the heating on full blast. I'm fairly sure there are no airlocks too. Any ideas what I could check? Someone at work mentioned it could be busted catalytic convertor returning heat back into the engine, but the car recently passed an MOT with no advisiories. However, the engine has been running noticibly hot recently (prior to the recent heatwave)

 

All fluids are the colours they should be, no gunk in the radiator reservoir, no seeping oil from the head, no leaks on the road, just lots of heat. I will get the head gasket checked again as an extra precaution, but I'm running out of ideas.

[Richard]

Gauge telling fibs?

[fiatdaft]

can i ask,how the water pump was checked?

[meggersdog]

what fiatdaft says.Sounds like waterpump impeller has broken,only way to check is remove the pump.

[reallyloud]

The gauge reading was something that was mentioned - being both french and electrical so I'll change that for piece of mind. The cam belt was done by a Peugeot specialist in Southampton - he told me that the water pump, the impeller not corroded and the bearing was fine, and obviously not leaking - I suggested he change it but he said it really didn't need replacing.

[Pillock]

I'd be sightly concerned that the coolant is the same colour when it comes out as when it goes in.... I've never seen an engine so clean inside that it doesn't fill the coolant with some level of murkiness, so that sort of suggests to me that it's not really circulating.

[Rocket88]

I'd put money on the water pump. Not changing them when doing a cambelt pretty much guarantees the little fecker will pack up just as you put the last bolt in the cam cover.

[red5]

Check the return pipe on the header tank - take cap off (carefully) and see if the (generally) smaller return pipe into the top of the tank had anything coming out of it. if not, it's bascially the water pump impeller either corroded off or spinning on it's shaft. Odd that a 'specialist' said it was ok and didn't advise/offer repleacment as you had thing in bits.

[GJR 11L]

+1 for the water pump. As Pillock said, it's odd that the coolant isn't even slightly grubby and if the pumps on these are anything like the ones offered as aftermarket replacements for some VW engines, then chances are that it has either a loose, plastic-bladed impeller or an aluminium one that's equally loose on its steel spindle.

 

BUT.... Yes, it's French and their electrics use reclaimed smoke that's already been used in cars with Lucas systems for twenty years, so it may just be the gauge.

Is the fan running longer than before? IE, does it coincide with the seemingly hotter coolant temps? Does the warning lamp come up?

[Pete-M]

I've been having a similar problem with my 3.5 SD1, except the gauge on mine was creeping up towards 120°C when the 'you've killed it' bit is at 140°C.

 

Didn't seem that hot, so I wandered to my local AC place, borrowed their thermoprobe thing and measured the radiator temp. It was happily there @ 85°C - about perfect.

 

On mine, it's the temp sender that's FUBAR - someone's fitted one from an earlier SD1 (I have the receipts) and the gauge is different on those.

 

I know this isn't the same problem, but temp gauge senders do go wrong more often than you'd think on 10-15 yr old cars. More modern stuff notices because of the amount of things the ECU measures and they compensate until it gets silly - then they flash the light up.

[reallyloud]

Is the fan running longer than before? IE, does it coincide with the seemingly hotter coolant temps? Does the warning lamp come up?

 

When the fan was working it would run constantly and recently since its stopped working the red warning temp light does come on when it reaches the highest temperature. The state of the coolant does strong suggest that there is a flow issue......

 

I shall use your collective thoughts (in order of piss-easyness) and investigate this weekend. I'm really hoping the water pump hasn't given up on me. This is the first major issue to go wrong with it - it must have overheard me when I mentioned that I might have to sell it....

[Richard]

The fan not working could be down to the hot water not reaching the fan switch. It's not looking good for your water pump.