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Bubbling expansion bottle !

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castorlex

Enthusiast
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39
Hello everybody! :)
My R4gtl/88 presents an issue. Bubbling of air (or exhausting gases) inside expansion bottle of coolant. First I thought that was an overheating problem because of electric fan or thermoswitch failure. I checked them and everithing is ok.Besides I made a complete bleeding of the system ; but today, early in the morning I realised that, despite I had open bottle to hear some "hiss" or vent residual gases, I started my motor (choked) and I noticed and instantaneous bubbling , I'm afraid that could be the head gasket..

what you think?

I appreciate your advices...
 
If you hear a hiss opening the expansion bottle when the engine is completely cold (cooled overnight) then almost certainly you have a head gasket failure. That's how I diagnose them.

A few air bubbles after work on the cooling system could be incomplete bleeding (I find it impossible to bleed the ststems completely, but they self bleed if you get it close enough).

Though I would suspect head gasket on your car. Be careful changing it - these engines are wet liner so you need to be careful not to disturb the seal on the bottom of the cylinder liner.
 
It should not bubble especially when cold. I would say head gasket too.
 
Thanks

Hello, good advice...next step : head gasket replacement...I will post more comments after that ...:)
 
doesnt sound good to me ,just to add if you have acess to an exhaust gas analyser that will check hydrocarbons (not just CO) a further test by holding probe above the level of the water in the plastic tank with engine running will detect HC
(my local friendly MOT station is usually happy to test for me)
good luck make sure if you end up replacing gasket that head is flat as may need skimming by an engineering shop

paul
 
mmm..One thing to add is that the last owner of my Gtl installed a thermometer in the back of the head, drilling it (a non professional work in my concept !!) for this purpose...I don't know if it is possible that air comes inside due to a bad seal adjust of that device?....:(
 
The pressure in the water system will tend to push water out of any hole with a lower pressure and will not let air in. Any air in bottle comes from cylinder or oilway
Allan
 
Hello...
I changed head gasket of may R4/88gtl. Bubbling in cold state stopped but now there is an overheating problem. My Temp meter shows 100-110°C even when electric fan is on... what should be the answer?. (I made a complete bleeding of cooling system before)..any suggestions... :(
 
Is your cooling system holding pressure? Often the seal on the expansion bottle cap is missing. How are you measuring the temperature?
 
thanxs Malcolm, how can I assure my cooling system pressurised ? (just with a perfect sealed cap of expansion bottle?). I measure temperature with a thermocouple attached to the head in the back side of motor ( I mean just in fron of driver side), I think is far enough from exhaust gases... .Actually bubbling begins when temperature reaches 100°C. One last data..head was properly skimmed before mounting...but I don´t know if it was poorly adjusted or what..
 
It seems that your cooling system does not hold pressure. It is common for the R4 engine to reach 100 deg. C on the back of the head but NOT to boil, as the system is pressurisesd, and even with plain water it should boil at a higher point.
If you have a spare radiator cap drill it and put a tyre valve on it, then with some means of compressed air supply equipped with a pressure gauge put pressure on it (13-15 lb/sq.in). It should hold at least one minute, if not it could be due to a leak somewhere (it will appear as water coming out), leak from the expansion bottle valve (air escaping from there) or internal leak.
If the leak is internal it could be from a)head gasket area (water in oil, oil in water or water in combustion chamber) b)liner paper seals (water in oil). or crack in the head (relatively uncommon). The best way to determine if the head gasket area is OK is to make a cylinder leakage test afterwards, if there is a problem it will show as air bubbles in the coolant.
 
My expansion bottle thing: I've noticed that maybe 50% of the Renault 4s I have been missing the rubber seal in the expansion bottle top so the system runs unpressurised and overheats. Maybe the seal drops out. It's an easy thing to check - just remove the cap and check there is a black rubber seal inside the cap.

Otherwise angel's idea for testing is a good idea - that will find the leak.
 
Malcolm, I made the test of loss of pressure and as it could not hold pressure so I decided to change head gasket. Besides I changed thermostat, and radiator´s thermocouple (a 82-92°C for a 72-82°) and in addition, expansion bottle´s cap. The outcome was a new set point of more or less 90°C. Fan motor works more often but temperature is well controlled.

thanks :)
 
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