Talk Morgan Forums Morgan Sports Cars Morgan Aero 8, 2012< Plus 8, SuperSports, Coupe & Aeromax Aero S1 temperature gauge/sensor fault

Hi Gents

So I checked the fuses and all look OK.

With the heater fan speed on max, heater temp set to min, and air con selected, the radiator fans are still not moving at all.

So, I guess I can't even take the car to a specialist as it may well overheat and I would not even know it until damage may have been done.

Maybe I'll just have to take off the wing and replace the temp sensor in the bottom hose, but if that does not work, I'll be pretty much out of ideas. Perhaps also see if I can spot an engine block gauge sensor as well to replace

It's not a temperature sensor in the bottom hose
Its the connector for the electronic thermostat for the engine

It's nothing to do with fan control

Simon@Sifab.co.uk
Sifabtemporary@gmail.com

If you have an OBD code reader you can often get the engine engine temp readings through that and will give confidence the temp sensor is working . It may help you get it to the garage. Note the fans actually come in at a high temp. I think 108c but please confirm with a responsible adult. The fans not coming in with the air con could be low gas or a faulty pressure sensor on the air con side. Let us know how you get on.

Hi Simon/Aero250

I have now found a diagram with the location of the the engine thermostat, & looks to be an easy enough job

With respect to the OBD reader, good call. I have one so I'll see if I can get a temp readout which will enable me to see running temp & allow it to run up. Can anyone support the approx 108 deg C cut in temp as Aero250 suggests?

Thanks for all help so far, including Alastair

Ian

It varies on the two I have.

The S2 has a slightly later derivative of your engine and tends to kick in just over 100 - say 103. When driving in open air it stays off and sits around the 90-95 temp.
The Coupe has the bigger 4.8 and runs higher with about 100-102 in normal driving and the fans seem to come in slightly higher as well.

Having the ODB is very helpful on the Aero as you do get a number of things that can cause the engine light to kick in. If you don't get the engine up to temp 2 or 3 times running you can get the engine light on which can be cleared with a good warm run, then off, then another good warm run.

Hi All

I thought I'd update all of you who were kind enough to respond, & also those who might have been interested watchers.

The generic OBD would read out engine revs, mass air flow etc, but not coolant temperature. So having bought an infrared temperature readout gun, and pointed it at the radiator top hose, I was able to run the car up to temperature with some confidence & see one of the twin fans come on which is a relief & it kept the water temperature around 104 deg C (the IR thermometer device has a 2% tolerance). The other fan would not cut in but I am wondering if that is called into service in hot weather countries.

And therefore I feel my problem is either a faulty gauge, wiring or sensor. Easiest to try first is a replacement bottom hose sensor. Would anyone know the (presumably) BMW part number for this

Thanks

Ian

The sensor is not in the bottom hose...

That’s the connector for the electronic thermostat...

Hi Simon

Thanks - Message received loud & clear :-)

So the only other temp sensor I can see is at the front of the engine above the drive belt and pulleys but I am not sure this is the right one.

You had previously said that the gauge sensor was discreet at the back of the driver's site cylinder head - I can't see it & even if I could it is likely to be a so & so to get at

Ian

I think that is the only coolant sensor. If you google e38 and e39 BMW’s with the m62 engine you get some useful info. I still think you may be seeing air con issues.

Hi All

Thanks for all your help, also special mention to Simon who had to persevere in getting the message through to me about it not being the bottom hose sensor!

I have replaced the temp sensor at the front of the block, and the gauge now works although somewhat erratically fluctuating rapidly in the lower ranges of the dial, peculiarly only giving a settled reading on a trailing throttle.I can however live with that until it next goes in for a service

Again, many thanks for all of your valued assistance

Ian