Topic

Hi all,

After a summer that started so well with the joy of my MG and trips planned including to the Scottish Highlands, things went a bit astray when I had an accident (NOT in the MG!!) where I tripped over a kerb and fell wrong breaking my shoulder joint .... so not such a good summer was had after all

Anyway, the upshot of this is that the MG has been sulking ever since I managed to get back on the road about a month ago. The latest incarnation of this was when the radiator sprang a leak (some body had previously used some form of rad weld and it appears that gave way). I stopped pretty sharpish and got relayed back home. The rad was replaced pretty easily (an easy job on an MG?? I didn't think it was possible!!), and I'm certain no damage was done to the engine or HG.

However ... since getting back on the road (again) the water temperature gauge seems to have stopped working properly (it never gets above the bottom two marks now, it did before) and the rad fan doesn't appear to be working (I'm not too sure this ever has worked looking back now). All the fuses are intact for the fan, so I'm thinking the relay has gone. I know you can take the relay out and put a wire across the contacts to check that everything else is working, but I'm not sure which pins / slots to wire across, can anyone point me in the right direction please?

Also, with the water temp gauge, could the sensor have got damaged when the MG had her sulk and got all thirsty? Is there an easy(ish) way of testing this? or is there a more likely reason for the sudden lowering of the temperature?

If the car is OBD2 compliant you can check the temperature of the coolant through the sensor the ECU uses. If this is low too then it points to something else, my guess is that the thermostat has stuck open so the coolant isn't reaching operating temperature.

That sounds possible with the thermostat, in the short term (2 or 3 months) will it do any harm? I need the car as a daily runner.

Unfortunately it's a 98 F so no OBD on the car though I have been looking at the pscan kit, I think that is high up my list for Christmas (or not long after!)

The issues with a duff thermostat are the car will run cool so fuel use will go up, the heater will not work well either. Unfortunately it's a pig of a job to replace.
It's possible the coolant isn't getting hot enough for the fan to run, but look in photos on the forum. I have a folder of useful piccies and the fan relay bypass is included.

Thanks David, I'll have a look at the photo's & double check the fan, then wait for a week off work to look at the thermostat.

Good news is that the thermostat on a '98 is much easier than later cars with a PRT.

This sound quite similar to the problem I have with my mk1 F.

My gauge hardly reads anything any longer but I know that the water temp gets up to 90deg fairly quickly (pscan) and stays there while the car is moving. However, at standstill, it goes up to 100 but the fan doesn't cut in. I've changed the relay but that hasn't worked but if I short the relay the fan comes on.

I suspect my gauge problem is the sensor, which I've had two abortive attempts at changing!

The rad fan is something else that I haven't worked out yet.

I'll be interested to see what you find

On the ZS180 the fan comes on at 102', it runs a Siemens 2000 ECU so might be programed differently.

The rad fan should come on if you unplug the brown coolant sensor as the ECU can't see the coolant temp.

Well it's definitely looking like a thermostat issue .... the heater doesn't blow as hot as it did, the rad fan only comes on if I short across the relay (I'll check the sensor when I next go under the engine panel just in case), and the oil temp doesn't quite get as hot as before, although the oil temp is close to where it was before so I'm taking this as a sign of a cooler engine unless anyone knows different.

The job will have to wait a little while 'coz I'm still in the process of returning to work and so time and money are in short supply. When I get to it I'm wondering if I should look at changing anything else on the cooling system. I'd like to swap the pipes under the car for SS ones.if money allows and I'm thinking about a coolant level alarm. Would it be worth getting to the water pump while I'm at it? Looking at the Rad & various bits I've got to I'm taking everything on the car as being original parts except the HG which I've got receipts for, so other suggestions to look at would be good.

Thanks for the help