There is more to life with TurboRenault.co.uk

Register a free account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members through your own private inbox!

  • This section contains the archived boards. They should be read only. If you want a thread resurrecting please message admin and we can move into the live section

Thermostat

J77HN W

New Member
On long or short journeys the engine never seems to go above the 3rd dot. I think the thermosat is knackered. Where is it located so i can take it out and test it. Any pics would be helpful. Cheers.
 
It's on the gearboxside of the engine under the alu piece where the main watertubes connect to.

Why do you think it's nackered? Normally I would the engine to overheat. Just carefully feel the waterlines and engine with your hands, when the engine starts from cold. The waterlines should stay cold for a while, since the thermostate should first shut off this side.
It's always a good indicator.
 
J77HN W":3hzfz2si said:
On long or short journeys the engine never seems to go above the 3rd dot. I think the thermosat is knackered. Where is it located so i can take it out and test it. Any pics would be helpful. Cheers.
You're not alone in this ... James has a similar problem on his and has yet to get to the bottom of it despite a replaced thermostat!
 
My car seems to take ages to warm up some days - it also seems to be related to ambient temperature which made me think the thermostat was faulty (stuck open). My hypothesis, based on the symptoms, was that the engine coolant would be flowing to the front radiator keeping the coolant cool relative to the ambient temperature and not reaching it's mid position for a long time, sometimes not at all on some drives ...

I had the car into Renault twice and they said it was within specs. I guess if the thermostat was stuck fully open it would never get to temperature and, since it does eventually, the thermostat must be working to some degree.

There are probably other factors at play and I am comfortable with things at the moment ... It could also be sensor related I guess ...

Martin
 
I also had the engine bay temp sensor replaced twice. Made no difference.:(

Everything was fine until the engine was taken out and put back in?
 
My car used to reach the middle i.e. 5 notch on the temp gauge.

But then i had the spark plugs changed and now it reaches only the 4th notch.

Dealer checked it out including sensors but found no problems, fans also kick in as well and no overheating.

I think a few people are having similar types of problems / questions though e.g. Clarkie said his wobbles or something?

Maybe retitling the post titled temperature gauge problems might get someone whose had the prob before to respond?
 
I've had this happen twice, replacing the thermostat fixed it both times, however there is a correct way to fit the thermostat and it needs a new seal i believe (one dealer didn't fit it properly so it got worse!). If this is not done correctly then it will not operate properly.

The problem with the car not registering optimal temp is excess fuel burn and a greater risk of the cats being damaged.
 
Well after my trackday at Spa, i'm going to need another thermostat - usual signs that it's not getting up to temperature and dropping on the motorway again! Seems that they fail under extreme heat, poor part - wonder if there's any possibility of an uprated version?
 
I'm still not sure why a thermostat would make the temperature gauge lower not higher e.g. the fault is they usually stick closed stopping the coolant circulating in the engine so it overheats?

Or are you saying the fault is that the thermostat fails to close properly e.g motorway driving will force more air into the rads so your expecting the thermostat to close a little to keep the engine at the optimum temperature?
 
Hi,
If there is a fault with the coolant temperature sensor you would notice that your fuel consumption has gone up because the engine management increases the pulse width of the injectors when coolent is cold and reduces the pulse width by percentage as the engine warms up. The same sensor also has a part to play in the operation of the egr valve which if it is not operating correctly the ppm of your exhaust gas emissions will also increase and have a detremental effect on the life of the catylictic converters.

Cold fusion
 
Yep, basically the thermostat fails to close properly. It seems to be a problem with all the thermostats i've had after the engine has been subjected to extreme heat (ie driving on a very hot day) or on trackdays where it's running at an extremely high temp anyway. Replacing it (properly) solves it, so I would prefer the same part from a different manufacturer if possible.
 
ok but in my situation I had my spark plugs changed then noticed the temp gauge was down 1 bar when hot, though the fans kick in ok.

Then I had a computer diagnostics which showed the sensors to be fine. Plus just had an MOT with emissions check and that was ok as well and fuel consumption has been about the same.

Interesting that you say very hot day - I live in Hong Kong and there are lots of hot days and I've even seen my car in temp gauge at 40c so it could be a good idea to change it bearing that in mind!
 
Has anyone replaced the coolant temperature sensor to see if this has made a difference? my replacement of the thermostat didn't solve it this time!

Where is the sensor located?
 
Right, had a bit of head scratching tonight. Took the plug of the sensor and the fans kicked in, so that's fine but doesn't eliminate the sensor from the dial problem yet until i fit the replacement.

The first thing was that the top radiator hose was warm after a short amount of time, say 3 minutes, same temp i'd say as the heater matrix hoses. But after looking at the renault technical diagram it seems that the "modine cooler" is attached to the radiator circuit. I'm assuming a modine cooler is an oil cooler, therefore there's not a lot of point using the radiator hoses to check if the thermostat is regulating properly?

My thoughts with the thermostat is the fitment inside the housing. I think if it is not fitted properly in the first place this allows coolant to bypass the thermostat?

I'm going to check the pipes closer to the thermostat housing tomorrow to see if I can get any more feedback there.
 
Personally I think nothing is wrong with your engine, but if you desperately want the needle halfway up, bend the damn thing.
My engine is always around the third dot.
See it from the bright side, at least you have enough reserve, due to the tempgauge , I wouldn't trust it though.

THE best method to check if the engine isn't too cold is adding an oiltemp gauge, but that would ruin the interior for some guys, don't know if you fall into this category.

If your not sure drive the car until it is on the third dot for about 5 minutes, then try to grab the waterhoses close to the cylinderhead, if you can't hold it for let's say 5 minutes, the engine is ok.

I also have one car where the temperature gauge stays close to zero, it went back on again when I repaired the aircon.
 
Update: Replaced the thermostat and now works fine, the temperature gauge sits on just under half way, and the engine fan cuts in on half way. I hope this helps anyone with similar problems.
 
Sesnsor changed, still got a problem.

I'm sure now that it is the fitment of the thermostat in the housing that is the problem. Will have to spend another £20 on coolant to sort it out.
 
Back
Top