hi, my civic 1994 sohc non vtec d15b2 is drinking water fom the expansion tank next to rad and sometimes it chucks all water back out so the expansion tank gets full and overflows. i have been told its a problem with matrix fan behind the dash. heaters work fine

i have done compression check on cylinders and seem fine.
also changed radiator and cap and thermostat. bleeded and flushed rad.

any help. thanks

 

What were the compression numbers? Maybe try a leak down test next?

My first thought was head gasket or cracked head making the pressure overflow the tank, but since you say the compression is good??

Does it overheat when it spits it back out?

When it drinks it, do you fill it up and it spits it out? Or does the coolant disappear?

 

You could have air trapped in the system, but It sounds as though your coolant system is not holding pressure at operating temperature and the coolant's boiling point is drastically reduced when this happens. Try getting your car's coolant system pressure-checked at a local garage and you'll probably find your problem.

If it doesn't hold pressure and you can't find any leaks, it could be leaking from the heater core inside the car, but a mechanic can determine that. I had a car with a bad heater core do what you described.

 

hi the car drinks the water randomly and also randomly throws the water out. when it drinks the water the coolant bottle goes emty and the rad water goes low so i fill it up so tghe rad is almost full and the coolant bottle is a little under half. now sometimes it simply drinks it again if driving slowly for a short distance but when driving in high reves in throws it out nd when the bottle is almost full the car starts to over heat after an hour or so of driving. there is no sign of water leak but you can always smell coolant from inside the car when driving even when heaters are off.

 

Just guessing here:
Since you only smell the coolant inside and don't get a puddle of it in the passenger footwell, I would say it's not the heater core.

Low speed the coolant is being burned through a small crack in the head gasket, head or block.

High speed causes said crack to open more and force exhaust into the cooling system causing it to over pressurize and burp it out.

You should get a leak down test or radiator sniffer test to rule out any cracks.