Club 80-90 Forums

Hi all

Could some one explain about coolant levels. Two tanks, i assume top is header/top up tank and lower is expansion tank. Should there be coolant in the expansion tank when engine cold?

there is often confusion on this subject......

here, in 80-90land they are known as
1.headertank - located in the engine bay, only accessable by lifting the engine lid.
2.top up tank - located behind the numberplate flap.

the headertank should always be full to the brim, always.
the coolant level warning light works from this tank.

the top up tank should always have some coolan in it, upto the fill hole when cold, often well above it when hot.

they work like this.....

when the engine gets upto normal working temp the coolant expands and is pushed out of the cap on the headertank, into the top up tank....... filling it above the max line....
when the engine cools the coolant contracts, causing a vacume which sucks the excess coolant back from the top up tank into the headertank, so if the top up tank has none in, its cant be sucked back.

often the cap on the later water systems fails, stopping the coolant being sucked back.
Also the pipe between the header tank cap and the top up tank perishes stopping the sucking happening, and in extreme cases stopping the coolant going to the top up tank in the first place.

Thanks Mocki thats a good explanation. Have to check hose between header an filler. Was watching what was happening, header full, and the fluid in there does expand when hot up to the hose that links header and top up but no fluid in top up tank.

RIGHT STEVE...WOULD YOU MIND EXPLAININ OW THAT TO MARLADYS VAN CAUSE IT STILL INNA PLAYEEN BALL!!!!