renault laguna temperature

Homer · Unread post by **Homer** » 09 May 2004, 13:30

Lets go back to basic cooling system diagnosis.
With the car stationary, run the engine. It should heat up until the fans cut in then the temp should drop and the fans should go back off.
Does that happen as it should? When the fans cut in is the radiator hot?
Normally, overheating at speed is caused by water not getting into the radiator. That could be caused by a faulty thermostat, a blockage or air in the system. Though it is unusual for the temp to then return to normal when you slow down. But I'm not sure yours is actually overheating.
Due to a lack of parts, I recently had to run my car without a thermostat. The temp would be very low unless I was either at a standstill or moving very fast. At 30 with a light throttle the temp would be running off the bottom of the scale. I wonder if that is your problem and the thermostst is simply not closing, or is the wrong rating.
When you say it rises to 'half way' are you sure half way isn't normal and it is dropping below normal when you slow down?
If you run the engine until the fans cut out as I suggest above then that is the engines normal temp. If it normally runs lower than that then it is running cold and the thermostat is suspect.
If the problem is electrical then why is affected by the vehicles speed? Engine speed I could understand but not road speed.[?]

mikgram · Unread post by **mikgram** » 09 May 2004, 19:06

The point of the voltage regulator is that the gauge may be giving a false reading when you accellerate the alternator puts out more power it may be that causing the gauge to rise .

Homer · Unread post by **Homer** » 10 May 2004, 13:47

The alternator speed will depend on engine speed not road speed.
So any effect of the alternator would fluctuate with gear changes and if the car was revved when stationary.
Need more info from grattsim really.

mikgram · Unread post by **mikgram** » 10 May 2004, 20:19

if you accellerate your engine rpm rises if you slow down it drops

grattsim · Unread post by **grattsim** » 10 May 2004, 22:25

So I'll change the voltage regular and see what happens. Yes when left to run it does warm up and the fan will cut in and out. To know roughly where the gauge should be I have compared it to other lagunas of the same spec. Although I wouldn't be surprised if air was getting into the system somehow?? I have also associated engine speed with road speed.

Homer · Unread post by **Homer** » 10 May 2004, 22:42

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by mikgram

if you accellerate your engine rpm rises if you slow down it drops
<hr height="1" noshade id="quote"></blockquote id="quote">
Depends if you change gear or not.[:)] Most people don't drive around in one gear.
Need to know what is meant by slowing down and if the symptoms can be replicated by revving the engine with the vehicle stationary.[?]

grattsim · Unread post by **grattsim** » 11 May 2004, 03:11

A good example would be generally moving at 65-70 the gauge stays higher, then as you slow down for a junction or to stop the gauge will fall again. The symptions are hard to replicate while stationary as the lack of moving air but it does slightly not to as greater degree as the gauge will fall by a lesser amount. I know the guage is expected to move slightly but not to the degree it does. I had considered if there was also a dodgy earth under the dash?

Homer · Unread post by **Homer** » 11 May 2004, 13:47

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by grattsim

The symptions are hard to replicate while stationary as the lack of moving air
<hr height="1" noshade id="quote"></blockquote id="quote">
That's just it though. If the symptoms are not there when the vehicle is stationary then it is most likely the moving air that is causing them, not the engine speed.
To be honest I'm not sure you have a problem.
It is obviously not overheating. It may be getting too much cooling and your symptoms are very similar to running the engine without a thermostat. (Or there may be an electrical fault.)
I was actually quite surprised how well my engine kept its temp on the motorway without a 'stat. It only really got cool when driving at medium speeds with little load on the engine. On one long downhill doing 30 to 40 on a trailing throttle the gauge dropped right back to where it would normally be on first starting.
I don't think your thermostat is closing properly. Or possibly it is closing at the wrong temperature. The new thermostat may not be to the exact specifications of the original part.
I could be wrong though.

mikgram · Unread post by **mikgram** » 11 May 2004, 20:51

ok no more talk of voltage regulators and driving around in the same gear at high revs.if the gauge is a bit high but not in the red it may be that there is nothing wrong with it on the other hand it may be an airlock Renault are notorious for them if any of your hoses have bleed screws open them up and bleed them. on my 97 2.2TD the the temperature gauge comes up to one stripe below the middle and never moves.even when I do 100mph or more.