Warm fuzzy feeling!
 

I have read that the diesels normally take longer to heat up and as a result, were originally fitted with the FBH. I just wondered whether mine is behaving normally as it takes just over 5 mins for the temp needle to reach 9o'clock position most days, as I cruise along the A96 at about 60. It is also very noticeable that its get quite warm inside the cabin quickly (I tend to leave CC at 21 Deg C) and this lasts for about 15mins then the temp drops. I bought a used FBH to fit soon but if this is normal behaviour, then i may not need it, as this also occurs when we have chilly temps up here (-6 last week!). Any thoughts??

ps I havent been able to get the digital temp displayed as my attempts to get test data up on the display fails - possibly not quick enough on pressing the trip button!

Normally the diesels take approximately 12 miles to get warm but if the Renault 5 thermostat has been fitted into the top hose then they do warm up much quicker.

I don't have climate just normal aircon and mine starts blowing warm air at about 3 miles so yours might well of had the same mod done.

I don't have a FBH fitted.

The worrying bit for me is that you say the temp gets hot and then drops off.. I’m guessing you might have an airlock somewhere.

Neil and Trikey,

Can you confirm that if you have a normal working thermostat in the engine
you can fit an additional stat in the top hose with no issue?

Thanks, Peter.

I was wondering about this but either a)its normal and heats the cabin early first or b) its a sign of the thermostat opening and overall temp then falling as water is cooled.

Its not a problem but just wondered! Will have to have a feel around of the pipes to see if extra stat has been fitted.

It has been done, BUT can cause cooling problems. It adds a second potential failure point in the cooling system. Thermostats don't always fail in the open position. There is also the amount of restriction of coolant flow with a second restriction in a system that was designed for one.

Don't do it. If the original fails open (usual) you could get away with adding the inline temporarily. How long is temporary? That's like asking "How long is a piece of string?". Me? I would take out the failed original and install a full size inline thermostat (not the smaller Renault one), so future replacements are easy.

Cheers,
Glenn

A 'normally' working original thermostat, does not require anything else, please confirm via digital readout that coolant temp reaches correct operating values when car is fully warmed up, after several miles of driving, if the car has never had a replacement original stat it would have almost certainly failed open.

I have the Renault stat fitted in my diesel, it has the original stat (sticking open) still fitted and has had no issues for the last 50k miles, I reckon that a long enough test👍

To be honest I don't know, I didn't fit it.

The original owner of the car did the mod.

All I can say is that in the past 3 years that I have had the car I haven't had any issues.

This was done by Jules and he explains it: https://www.the75andztclub.co.uk/for...+thermostat%29

As far as the engine getting up to temperature in the time described sounds about right. I'd treat the cabin temperature as a different issue.



I think I'd be checking to see if the cabin temperature sensor is blocked up (internally) with fluff. I strongly suspect our 1.8 is.



Also when it is cold in the cabin and the engine hot, with the AC on fully auto it will blast a lot of hot air into the footwells until the sensor detects the desired temperature. Once the temperature is reached it will moderate the amount of flow and the temperature of the flow - which can feel like it all of a sudden blows cold (especially over the knees). I strongly suspect that this effect is exacerbated if the temperature sensor is effectively being insulated from temperature changes by being full of fluff so giving a delayed reaction to temperature fluctuations.


Just a theory of course...