OP
@louswheel avatar
UTC

Molto Verboso
150 Sprint Veloce, RE Meteor 350
Joined: UTC
Posts: 1270
Location: St Neots Cambridgeshire England
 
Molto Verboso
@louswheel avatar
150 Sprint Veloce, RE Meteor 350
Joined: UTC
Posts: 1270
Location: St Neots Cambridgeshire England
UTC quote
Does anyone know if the coolant cap is breathable?? The reason I ask is that although I changed the coolant, following my water pump change, I've noticed that small puddles of coolant have appeared on the floorboard. On further inspection, I discovered that coolant was hissing and frothing out of the cap! it had the image of a small foam party inside the coolant tank! I realised that the coolant dripping onto the floorboard has come from the cap!
I let the engine cool down and then ran the engine without the cap on. A bubble of air soon belched out of the coolant which suggests that was the reason the coolant was all frothy, and I put back the cap, and so far no froth...
Do you think that there
A. there is/was an air lock somewhere in the system
B. The cap is no longer "breathing" as i think it may have trapped air in the
system
C. The addition of "rad weld" was added to find the source of the "leak" caused the frothing and compounded the problem, and so i need to flush out the "rad weld"
Any thoughts??
Graham
@jimc avatar
UTC

Moderaptor
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
Joined: UTC
Posts: 44567
Location: Pleasant Hill, CA
 
Moderaptor
@jimc avatar
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
Joined: UTC
Posts: 44567
Location: Pleasant Hill, CA
UTC quote
The coolant cap should contain pressure up to 3bar - above which it should release coolant.

Cheapest test is to replace the cap with a new one, and if it happens again then you have an overheating or head gasket problem. The fan should come on well before the temperature is so high that the pressure gets to 3bar. The fan switch temperature is about 103°C.

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