# Renault Megane overheating



## surge2k1

Hi I have a renault megane which is overheating. About 8weeks ago I was on the motorway when all of a sudden the temp flew up and engine stalled - Blown cylinder head gasket. I replaced the gasket and re-tightened the head in order with a tork bar to create the seal. It was ok for 4 weeks or so when the overheating problem started again. The engine is definitely burning off water and for the moment I am getting by with carrying 3 litres of water everywhere, If it overheats I remove the cap, let any water that is left boil up and then refill it. Usually when it is refilled the engine will operate at normal temperature for a gd few miles, clearly this is not ideal. When the car is beginning to overheat it is accompanied by no heat coming from the dash board blowers. Somtimes the blowers work itermittently with the engine overheating when they stop and the temp lowering again when the heat in the blowers returns. Would be greatful for any help someone can give!!

1) I think the gasket has gone again but why? I checked the head was not warped any when changing the gasket.

2) Why the intermittent overheating and blower problems? I think the heater stops working because no hot water is left to pass through the system but this doesnt explain why it sometimes starts working again??

3) The radiator fan works.

4) When driving a loud pouring noise can be heard from the passenger footwell at times, like water pouring through the system, could this mean an airlock giving me grief?

5) And finally, recently the car appears totally dead when tryin to start, ie the starter motor wont turn, this can be resolved by putting it into gear and pushing the car a foot or so. Is my engine seizing and proving too much strain for the starter motor?

:smile: haha I realise this is a beast of a post but any help on anything at all would be greatly appreciated!!! Is it all connected????????

Thanks in advance, off to try and figure out why my laptop is even more buggered than my car! :4-dontkno


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## surge2k1

Forgot to mention, the car usually struggles to start, ie must turn over several times and also runs rough around 1500 revs.

Cheers!


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## SABL

The lack of heat from the blower is due to lack of water in the heater core which is part of the cooling system. This is a common symptom of low coolant.

If possible do a compression check before removing the head. Inconsistent readings between the cylinders will indicate if leakage is present.... look for low pressure in 1 or2 cylinders. If this is the case you might have a "burn out" between cylinders and is most often found in engines with aluminum heads. Check for burn tracks between cylinders on the block and head.... all surfaces MUST be absolutely smooth. Let's just hope the compression test is OK.

The next step (or maybe the 1st step) would be to check the noise coming from the footwell. Is that where the heater core is located or is it nearby? I would check there to make sure the core is not the cause for the loss of coolant/water. A blown head gasket will sometimes create excessive pressure in the cooling system and cause the heater core to fail. 

Another thing to look for that may indicate a head gasket problem is the presence of an oily or sooty film on the coolant. This must be checked before the coolan level becomes too low or you may drain some of the coolant into a pan and look for any abnormal "film". Also, there will be lack of pressure on the cooling system soon after shutting off the engine ... but this is not difinitive because a failed heater core will cause the same symptom. What will point to a failed gasket or head will be excessive pressure in the cooling system while the engine is running..... remove the radiator cap, fill the cooling system and start the engine. Carefully look for constant air bubbles in the coolant. A constant supply of bubbles will indicate the engine compression is leaking into the cooling system and overpressurizing it.

An overheated engine will be hard to start.... yep, it is trying to seize due to expansion of the moving parts. Not all parts are made of the same materials and expand at differing rates. The clearances are designed for normal operating temperatures and when the engine overheats, those clearances are diminished which cause the seizing effect.

One more point..... you really scare me about your removing the radiator cap while the engine is overheated!!! I did that once, about 30yrs ago, it put me in the hospital with second degree burns on the face and chest......no fun and took a long time to recover. It seemed that I would never be able to raise my arms above my head again.

Let us know how things are progressing and best of luck,
SABL


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## SABL

OOPS, I just noticed (or paid attention to) the mention of hard starting and rough idle/running. That could be an indicator of a breach in the head or it's gasket.

If forced to pull the head again, take it to a shop and have it checked if a defect is not readily apparent. Most shops can "magnaflux" the head to reveal any cracks or defects. Any "scoring" of the head or engine block in the area where the gasket failed will mean more than just replacing the gasket itself. If it is the head, sometimes it can be surface ground to remove any scoring/grooving but care must be taken to ensure that piston clearance is not lost.

SABL


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## daz75

Hi,

jees, it was a mega post. If the head has gone again so quickly after repair either the job wasn't carried out correctly, i.e - how was the head checked for warping?, Im guessing it wasn't crack or pressure tested, could there be some damage to the head, any damage, even slight to the surfaces could cause problems. As all ready mentioned - check in the coolant expansion tank, also check for a cream like substance under the oil filler cap & on the dip stick. Is there any smoke coming out of the exhaust? Also, when you re-filled the coolant did you bleed the system to get rid of any air, this causes air locks & prevents hot air blowing.

Hope this may help?....:4-dontkno

Daz.


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## zgazga

*Renault Megane stopping while in motion and overheating*

I have a problem with my car, it switches itself while I'am driving and I have to re-start it a couple of times before it can start, but then it stops again after a few metres. when I open the hood the water bottle is very hot, the engine is overheating and the fan is not running. What could be the problem.

I would welcome all the help I can get, as I'am not familiar with the mechanics of the Renault megane 1.

ZGAZGA


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