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Discussion Starter · #1 ·
hi guys i have a little problem with my car, ill try describe the problem in such a way i dont confuse people lol,

ok firstly i have a renault laguna 1.8 RT sport 1997.

yesterday i was driving home and noticed the temp gauge way higher than normal, pulled in and switched engine off, started back up and same happened, phoned AA.

They came up with the conclusion that it was either a sticky thermostat or water pump, while i was standing there with the AA guy it never overheated :confused: thats mainley why he thought sticky thermostat.

Today i replaced thermostat and everything seemed ok until the temp started creeping up again then went to the top end of the scale. sometimes it will balance at the 3/4 mark which is normal and other times it will shoot right up to the max mark almost,

also noticed when the temp is balanced at 3/4 mark, when i turn on the heating in the car it will quickly put the engine temp up, why would this be?

as i stand the thermostat has been replaced, im now thinkin either water pump or head gasket?

im stuck now and need it sorting quickly as my mrs is pregnant and need the car.

sorry for the massive rant and i hope some1 can help me out.
 

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With the engine cooled down a bit, open the Water filler cap.
Any oil mixed in the water ??.

Simliar, pull the oil dipstick, any cloudy / milky looking oil ??.

With the water at the correct level. Remove the water filler cap.
Start the engine, and let it run for 1 min.
Rev the engine a few time to around 4000rpm.
Does the water rise, and overflow into the engine bay ?.

Answer yes to any of these 3, and you have a Head Gasket gone.
 
G

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Is it loosing coolant?

You say it's over heating based on the temperature dial? I wonder if maybe you might have a faulty temperature sender unit?
 

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Discussion Starter · #4 ·
thanks for the replies guys i shall look into it tomorrow as the car is parked at my work.

also how would i check the temperature sender unti?

also there is not oil residue in the water tank and also no milky stuck at the oil filler cap.
 

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Firstly,is the car actually overheating?.If not,it could be a faulty temp sensor (as said above) or a poor engine earth connection (had this before on a car identical to yours,a new earth wire sorted the fault).

Is the heater hot when the engine is up to temperature?.

Is the radiator warm across it's entire area?.

Did you bleed the system when you fitted the thermostat?.
 

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Discussion Starter · #7 ·
i can confirm that the heaters are roasting hot when they r on.

i shall check all engine earths soon as i get to the car.

i left the filler bottle lid off and let engine run in order to let any trapped air escape. or have i done this wrong?

ok so how do i check that the temp sensor is infact working properly?
 

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There should be bleed screws in the system,I forget exactly where they are now but there's usually one on top of the radiator,one in the heater pipes,and possibly one near the thermostat housing.Sometimes you have to undo and lift the header tank up get the air out,but that's unusual.It doesn't sound as though you have air in the system now though as the heaters are hot,usually the air will get stuck in the heater pipes/matrix and give a cold heater.
 

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Discussion Starter · #11 ·
the temp gauge goes hot even when driving, havent tried it while the heating is on tho.

the fan comes on but sometimes when temp is around half way and some times when it is very very hot ( acording to the gauge ) i do agree its like a wrong reading somewere but untill i check the car tomorrow i wont know lol, ill post up results tomorrow

thank you for all your help people very much appreciated :cool:
 
G

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If the head gasket was failing there are several things that could happen oil mixing with coolant and vice versa but you say that doesn't appear to be happening. The coolant system could be getting over pressurized with combustion gases getting forced into the coolant which would cause it to get forced out of the expansion tank. But you haven't said if your loosing coolant?
 

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Just to reiterate, check your coolant level. Even a small leak somewhere will eventually drain your coolant level to the point of over heating.

Though your symptoms really do sound like dodgy readings/faulty sensor
 

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My step daughters Clio had similar issue with overheating...??
garage said faulty thermostat and she was losing coolant....
when she eventually broke down, AA chap found a small leak on a pipe that was out of sight !!
because the pipe was small and not highly visible any coolant was trickling down the back of it and leaving no tell tale marks on the driveway...
obviously as the engine warmed the coolant, the pipe expanded and then started to lose the coolant...

Then there was air in system to bleed out...all ok now though...
 

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Discussion Starter · #15 ·
ok just to update heres my results today

no oil mixing with water
radiator hot all over

2 things i wanna check tho, when i rev the car i get coolant rushing into the filler tank is this normal?

also when i put my heaters on the temp gauge goes up to nearly max why would this be?
 

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Discussion Starter · #16 ·
just to update, the head gasket is the problem, would you recommend a garage doing this or can it be a DIY job? need to know tonight as i have to make decision 2moro lol. any any1 got a how to guide?
 

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Discussion Starter · #18 ·
put it into the garage and they done pressure test to confirm, i am loosing coolant but no leak anywere, when rev engine it forces coolant into the coolant bottle, when turn heater to hot the temp gauge goes up fast.
 
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put it into the garage and they done pressure test to confirm, i am loosing coolant but no leak anywere, when rev engine it forces coolant into the coolant bottle, when turn heater to hot the temp gauge goes up fast.
But that doesn't mean you've got HG failure. It could be the water pump seal is leaking or even a corroded core plug. If the leak is slight the coolant could be evaporating away before it gets chance to drip on the floor?

A "sniff" test on the expansion tank should detect traces of combustion gases in the coolant
 
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