Hi,
I don't seem to have any warm air coming in through to the cabin of my 1998 1.4e Renault Megane. A couple of days ago the air was a little warm if you let it come in on its own (i.e whilst driving without the blower on). Now there is no warm air at all and it's freezing cold at the moment. Can anyone suggest what it might be so I have an idea before taking it to a mechanic? Also after a long drive i have noticed a hissing from the colant bottle- the level is fine. The cap is on as tight as possible and the connecting hoses are ok. What could this be? Thanks in advance.
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Sounds like you've got a blockage in your cooling system, so hot coolant isn't getting to your heater matrix. It might be something like an air-lock which should be clearable by unscrewing the bleed screw(s) until coolant pours from them. However, you only tend to get air-locks when you've refilled the coolant, not out of nowhere if you've not been fiddling with the engine. So it could be some debris causing a blockage, when was the last time the coolant was changed?
I recently had to change my heater matrix which sprung a leak (soaking the passenger footwell) after a coolant change. There was a blockage in it, so the coolant forced its way out through the side of the matrix instead. So it could be you matrix which has a blockage in it. While a matrix is under £40, the amount of time it takes to fit is roughly... forever! You've got to remove most of the interior to get to it, while not techically difficult or needing special tools, it is a right mare of a job. I did it myself which probably saved my a few hundred quids worth of garage labour; but it did take a long time.
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Sounds awfully like a head gasket problem to me...
No water in system = no heater in car. Cap simmering = releasing pressure put into system by failed head gasket.
Needs looking at by someone who knows pronto, else it might be a new head a well as a gasket and that costs £££££ rather than just £££ for the gasket....
--
RichardW
Is it illogical? It must be Citroen....
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Thanks for the replies. *Davemar* The coolant was renewed at the last service in early September. Shouldn't the airlocks have been removed after changing the coolant? Should I try the bleed screws suggestion. If so, is it difficult to do?
I hope it's not the heater matrix as you say. Just checked the coolant and it's fine but just noticed some of the rubber on the seal (of the cap) is broken??
Thanks
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I had this exact problem on my Polo, a day before I looked further and discovered the head gasket blown.
Check under your oil filler cap for mayo like stuff, and see whether theres lots of white smoke coming out the exhaust.
You really should not drive it until you've checked those things...
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Hi,
Checked the oil cap and inside the engine- no mayo! Coolant is a purple colour with no mayo. I'll check the exhaust tomorrow morning. Thanks.
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There is a chance that after the coolant change you have an airlock. On renaults there are little bleed screws (black serrated edge bout the size of an half p) on the tops of most of the large coolant hoses. they need to be undone till coolant comes out and retightened. They dont need too much force to undo, if a finger wont do it then gentle use with pliers will.
Agree that it sounds like head gasket tho as Richard says, gets the garage to use a sensor to smell the coolant for combustion gases. If the gasket is going get it done asap to prevent worse (read expensive) damage.
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Oh dear! How much would it be to get the head gasket changed?Just found a head gasket set for £30 plus vat so how long would this job take? Does the job involve interfering with the cambelt (if so i'll have that done at the same time)? Cheers.
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Hi,
Tried the bleed screws (well one of the two) and coolant came out straight away. The other one from/to the matrix has a plastic cable tied around it so I can't undo it??
If the head gasket was leaking wouldn't the coolant level go down? It hasn't in my case. Anyway thanks for the help the car is going to the garage as soon as possible!! Remind me to never buy another Renault Megane!!
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I had a very similar problem on my 1.4e 1996 Megane. I flushed the system but when it came to draining it couldn't reach the block drain plug. I then refilled it, bled it, all apparently OK (plenty of water coming out the bleed screw - and damn hot!!!)but no heat. I then discovered that the heat started to come through after a good thrahs over 15 miles at 80mph. Thought it was fixed, but next day on short run (5 miles at no more than 50mph, no heat. So I then went out of my way to drive a linger distance at faster speeds, and over a period of a few days, the heat arrived on demand. Might be worth a try.
The only thing I can conclude is that the faster driving pushed the water round the system with more pressure, and subsequently shifted a blockage. The system was pretty clagged up, and I think the car had only been used on short journeys before I got it. I still have fears that the matrix is on its way out, as I can sometimes smell antifreeze, but it isn't losing water.
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