High temps, no fan and no heating

[krisby]

So we were coming back from Staines today, driven maybe 10 minutes, a few miles and I noticed on my phone (connected to the ECU) that the temperature was close to 100, then 110, I noticed the cars needle carry on past 90 as well, then to just under 110 before I found a side road to pull in to.

The radiator fans weren't working, so I checked the fuses on the battery, all fine. checked expansion chamber, it overflowed cos it was pressurised, no sludge, squeezed pipes, and seemed fine, all hot too.

After letting it cool awhile started again and turned on heating, but there was no heat at all coming from vents.

I also noticed a slight whirring coming from the engine bay, could just make it out over the engine idle, sounded like a motor or something trying to turn, or open, I'm guessing that could be the thermostat, and most likely is a buggered.

Any help would be great, I left the Mrs with the car waiting for the RAC, so I'm driving back now in my car to swap with her. I'll check back later.

 

[krisby]

stupid RAC still hadn't called, so I risked driving the 2 miles home, considering it had started snowing, I thought if I left the bonnet on the latch I can get some extra cooling under there.

The temps on the ECU were 42C, and the needle was at the bottom, so 3 miles to home, driving slow, should be ok. No, immediately rose, hit 100C at the 1.5mi marker, ran a red light, had to slow for the next one, put it in neutral (automatic), temp stayed at 108c, as I pulled away another 1/3 mi and temps were at 114c, pulled into laybe, let it sit for 10 minutes, dropped to 101c, and risked the final 2/3mi, coasting some of it, and tip toeing the rest.

Car seems fine otherwise, but still no fans, no heat from vents, even set to max temp and fan speed, and A/C would not stay on, the snowflake turned off straight away, which it normally doesn't do.

So I'm hoping just a simple thermostat, assuming I can get it to a garage before it gets too hot again.

Shoulda said, 1.8 SE 20v, non turbo.

 

[Muttley]

Sounds very much like the water pump to me. The thermostat isn't motorised, it is a simple mechanical component opened by a wax capsule that expands as it heats up.

Lack of heat from the cabin heater will be because the coolant wasn't circulating.

Rad fans are triggered by a sensor in the radiator itself, and if there was no coolant circulation then the radiator will have stayed cold.

If it is the water pump, change the cambelt and tensioner at the same time - they have to be removed to get to the water pump, which is driven by the cambelt.

Will cost in the region of £500 at a garage, I'm afraid. Get a compression test done too, to give you peace of mind about the head gasket.

Hopefully someone who's had it done recently will give a better price estimate.

 

[krisby]

bugger, that was the sound I heard then. Oh well, I better find a garage to do this, I'll check the service history too cos I thought the belt had been done, maybe it was but not the pump.

Anyway, thanks.

 

[krisby]

actually muttley, just dawned on me, shouldn't the fans still turn on though? Neither was on, despite the 110c temps.

Should I also be concerned that the needle on my car is considerably less/slower to react than my digital readings? When I was seeing 110C on my phone, the needle was a shade over 90, before starting to rise. Only the first time did it actually get to near 110 on the dial, but all other times it only moved just above as I shut off beforehand, but still way less than the live readings.

 

[Muttley]

The reading that you are getting on your phone (presumably through some bluetooth adapter on the OBD port) are the readings from the 5V "digital" sensor in the CTS. There is also a 12V sensor in there that feeds the dashboard gauge. I'm guessing that this is because the moving-pointer gauge is a holdover from older cars without ECU's and there isn't a 5V version of it - either that or they want to keep it separate.

The reading off the OBD port is the same data that is being supplied to the ECU and is expected to be accurate. The dial on the dashboard is not anything like as accurate and is really just a general indication of how things are going.

You've reacted to the real temperatures and not the dashboard indications so that bodes well for your head gasket.

The radiator fans work off a completely separate system, almost entirely separate from the ECU. They have a thermoswitch embedded in the radiator itself, and only pay attention to the temperature of the coolant in the radiator. If the water pump had completely failed (which is what it's looking like) then there would have been no way to get all that hot water into the radiator, so it will stay cold and the fans will stay still.

The engine CTS is in the coolant pipework next to the cylinder head, so it will see the heat of the engine even without coolant circulation.

If you do have to replace the water pump then it's still a good idea to change the cambelt and tensioner too. The cost of the components is trivial compared to the labour to get to them.

 

[krisby]

cheers muttley, explains the non working fans, certainly puts me at ease its not a 2 or 3 fold issue. I'm pretty sure head ok, no sustained driving at high temps and the top of the engine actually felt pretty cool initially, and the 2nd time defo was cos it was getting cool air under the bonnet.

hopefully my car guy can do it monday.

 

[Muttley]

The failure we seem to hear about most often in the forums is of the variety of water pump that has a plastic impeller attached to the steel spindle driven off the cambelt. The plastic impeller is more prone than it should be to breakup, reducing the efficiency of the pump and clogging the system with bits of impeller blade.

However I think you've had the less-common problem of the impeller separating from the shaft, so the shaft is spinning but can no longer move the impeller blades. So no circulation at all, and without any warning.

For this reason it is received wisdom that you should always replace the water pump with a metal-bladed one whenever you first change the cambelt. Once you've changed it, you shouldn't need to do it again.

 

[krisby]

was indeed water pump, and fortunately it did happen as my guy reckoned the belt was pretty close too, but all in pretty good, £280 for WP, cambelt and tensioners, coolant and labour. Not as bad as I thought it might, and now I know I can go and redline it to my hearts content, as long as the gear box can cope.