Coolant Level

[m.crawford]

I recently noticed a snail trail of coolant down the front of the expansion tank and so I got a new cap from eliseparts. Today after a run the coolant level looked much higher than it used to. Just wondered if anyone had an explanation for this - could I have let some air out when I changed caps - there was a slight hiss when I opened it even when cold? Also, could this be the start of any problems?

Thanks

Martin

[Victor Meldrew]

I recently noticed a snail trail of coolant down the front of the expansion tank and so I got a new cap from eliseparts. Today after a run the coolant level looked much higher than it used to. Just wondered if anyone had an explanation for this - could I have let some air out when I changed caps - there was a slight hiss when I opened it even when cold? Also, could this be the start of any problems?

Thanks

Martin

Sounds normal to me...

When the car is hot it vents any excess pressure through the cap.. as it cools it eventually drops bellow atmospheric pressure so you will hear a hiss as the air equalizes.

[m.crawford]

Thanks - just being paranoid I guess.

[robin]

Your owner's manual explains all. The coolant should be at the min line when cold and should rise to the max line when hot. Every car has it's own "cold" level which it will settle to if overfilled; excess coolant is vented through the cap; also as the cap begins to weaken, it will blow sooner and so you'll lose a little coolant as vapour along the way.


Whatever happens, when your engine is hot the coolant level should rise. If it drops you have gas in the system - probably the radiator. That can come from poor filling, poor bleeding or head gasket failure.

Cheers,
Robin

P.S. Assumes you have a K-series car - not sure how the Toyota one behaves, but imagine it is much the same (the physics is the same, after all!).

[m.crawford]

Thanks Robin.

It seems to have settled down in the last couple of days to normal behaviour, and no more goo on the side of the tank since the new cap.

Martin