Mysterious coolant leak.

renault8&10

renault8&10

Well-known member
VIP Paid Subscriber
1000+ Posts
Fellow Frogger
Joined
Mar 9, 2002
Messages
4,813
Location
Sydney
One for the brains trust. I keep losing coolant on my 206 1.4. To give an idea, I top it up then it will go from max to min over about a two week period - the car does very little k’s.

I use Nulon long life red, so any leak is usually pretty obvious as it dries a bright pink colour. Some facts:
The cap appears to hold pressure - it pops when I release it. I always screw it down fully. The plastic bottle appears OK.

There are no obvious leaks anywhere at the front - radiator, hoses, thermostat, heater hoses in the engine bay that I can see.
Timing belt was changed 4 years ago, but no idea if the water pump was done. It would have been done by Bill M in ACT who is pretty thorough by reputation.

There are no leaks visible in the cabin that I have seen - where do the orings and matrix normally leak at - where to look for leaks?

The oil cap is Ok - no condensate underneath; the oil on the dipstick is clear. Beyond that I haven’t done any leakdown test or similar. The car appears to maintain temp and while it runs higher than I consider normal, not what appears high for a 206 (generally 80-90 by the gauge).

The previous owner did have some heater O rings replaced twice over his ownership.

Any ideas on where to look/try next.
 
Under car, look at nighttime, when everything is cold, leaks from water pump show up as wet even though it is pink, evaporates off when hot and so looks good
When it is under pressure no leak from water pump.
Lift carpets again when cold.
Pressure will seal o-rings, no pressure will leak easily if incorrectly fitted.

Temp gauge is an indicator actual temp will be above 100degC but pressure cap stops it boiling
Pressure cap may be faulty as well ??
 
I don’t know the 206 at all.
My experience with a 306 is this.
There is a plastic connector on the firewall. It links the heater hoses from the engine to the cabin. Mine developed a small crack at that point (in the engine bay side).
Coolant leaking. Several mechanics. Radiator repaired, New radiator. Many hundred dollars.
In the end it was a simple fix, but I seem to remember that the connector block was quite expensive for a plastic moulding.
I hope this helps you find your problem.
 
Pretty common on 1.4s to leak at the head gasket


Garage C5 X7 3008 XTE
Gone but not forgotten 206 GTI 180 306 XR SED 405 MI16 x2 xzara VTS 406 SV 206 XT Berlingo 2011 (best car ever) 306 HDI 307 XSE HDI touring
Fix it right the first time
 
dmccurtayne said:
Pretty common on 1.4s to leak at the head gasket
Garage C5 X7 3008 XTE
Gone but not forgotten 206 GTI 180 306 XR SED 405 MI16 x2 xzara VTS 406 SV 206 XT Berlingo 2011 (best car ever) 306 HDI 307 XSE HDI touring
Fix it right the first time
Click to expand...

Ouch. The only coolant losses on our 306 were thermostat housing and heater radiator (several times) and the sources were easy to see.

Good luck KB.
 
No, the carpet does not show any marks or spots.

I did find some spillage on the fuel filter and lower suspension at the very back of the engine bay, but not sure if that is there from bleeding the heater hoses last time I flushed the coolant. Might try to clean that off and monitor.

Would that be the o rings if it leaking there?
 
My suggestion results from wife's 308 HDi auto. The coolant leak was not as bad as yours but nevertheless annoying because they shouldn't lose any coolant. The mechanic used a pressure tester when it was hot and wound the psi up when no leak showed at low psi and eventually shook his head and gave up on trying to find it. A week or so later I found that in doing the pressure test he had removed the leak. The plastic 'o' ring in the coolant container cap had failed. Swapped caps and now no more leak
 
dmccurtayne said:
Pretty common on 1.4s to leak at the head gasket


Garage C5 X7 3008 XTE
Gone but not forgotten 206 GTI 180 306 XR SED 405 MI16 x2 xzara VTS 406 SV 206 XT Berlingo 2011 (best car ever) 306 HDI 307 XSE HDI touring
Fix it right the first time
Click to expand...

Give it a dose of chemi weld ?
 
You must log in or register to reply here.
Top