Charles

[Charles]

Apologies if this has been covered before. Any help with the following would be greatfully received:

We have an R4 L 1988 in very good condition, acquired about 2 years ago, and running well until recently. Lives in France. On return from over wintering in the UK after severe winter in France (down to -17 C) car started first time but after running about 1 km or so temperature warning light came on. Noticed that the fan had not switched on. Wondering if the thermostat/ temperature switch was stuck started investigation. First noticed that car had a replacement radiator with 2005 label (?? may be an R12 radiator), but no obvious leak. Thermostat was not in standard position close to the upper hose but incorporated in the bottom of the radiator on the driver side. Shorting the leads to this brought the fan on and running the car over 1 km the temp light didn't come on. Thinking that this indicated need for new thermostat, replaced this with and also replaced coolant. But same problem, light on after same distance, no fan on......

What's the likely diagnosis? What do I do next?

Grateful for any help


Cheers, Charles

 

[Cornish4]

Hi there Charles, it seems a bit strange to me that the thermostat is in the bottom hose, and unless I'm missing something here I would say it won't work right there. As I expect you know the whole point of it is to isolate the coolant in the engine from the radiator until the coolant warms up, in then opens to mix with what's in the rad. I reckon this is why the fan doesn't start up when it should as the gauge sensor is in the head, but the fan sensor is as you know in the radiator. I could be talking jibberish here and I expect someone out there will tell me so, but.........well good luck anyway:smile:

 

[jonigel]

Did you replace the fan switch or the thermostat? Because only the fan switch will make the fan work,thermostat must be in the top hose to work.

 

[Cornish4]

Sorry, for gauge read warning light.:smile:

 

[lazyduck15]

Is it a mechanical thermostat attached inside the hose where hot water returns to the radiator ( I mean the hot side)? If such is the case, it might be seized closed and by that not letting hot water being cooled by the radiator and then not shooting on the fan electrical switch.

 

[orsome]

thermostat

Is it a mechanical thermostat attached inside the hose

**just to take out it completely and run without any thermostat for a while.Motor temp will be lower but you will find the problem, i guess it must be electric connect problem.I have the same type of hose thermostat.

 

[pepper]

The piece your fiddling with is the thermo switch for the cooling fan! The actual thermostat is in the top hose next to the engine, normally held in with a jubilee clip just next to he jubilee clip that holds the top hose on!

You need to be looking at the hose right next to the engine that fits onto the water pump!

 

[Charles]

Thermostat problem - Charles

Many thanks for putting me on track with your advice. I was confusing the fan switch housed in the radiator with the thermostat in the top radiator hose. I located and removed the thermostat in the hose and confirmed that it doesn't open. Will delay replacing it and see how the car runs . Over about 4 km no temperature warning light on . The fan didn't come on at all, the radiator didn't seem very hot. Will check that it does so on a longer run.

Presume there's no problem with running the car without the upper hose thermostat??

Again, many thanks to all for your help

Charles

PS where is the temperature sensor located on the engine?

 

[Cornish4]

Hi Charles. You can run the engine without a thermostat but it will take a lot longer to warm up, will run less efficiently and use more fuel. Better fit a new one as soon as possible, in the top hose:smile:
The temperature warning-light sensor is situated in the top of the cylinder-head, at the back, passenger side, (RHD car), just above the exhaust manifold. Regards Brian.

 

[Charles]

Thanks Brian. Had the feeling that the advice from someone here about running the car indefinitely without a thermostat somehow wasn't right. It's so long since I dabbled in DIY car maintainance on a Morris Minor, have forgotten the basics. Ruby ( our red Renault ) is now running nicely without any worrying lights on ! Will get a new thermostat soon
Regards. Charles

 

[Cornish4]

Hi Charles, I'm glad to hear Ruby is running better now. Happy motoring, regards Brian