scubbydubby555

I have just replaced the radiator and just wondered if this is correct? when i star the Scooby the top hose on the radiator get warm and the bottom one is cold? it does not seem to be overheating, and the heater is working fine.

Can anyone help

davedipster

When the coolant gets to 80 the bottom hose will become warm.

Let it cool down and remove the rad cap, fill up to the brim.
Then Check the coolant level in the clear expansion tank and fill to max.
You need to fill these cars painfully slowly to stop air getting trapped by the way.

davedipster

Once the engine gets to 96 both fans should run on slow speed when stationary.

scubbydubby555

I will try this Dave but i have run it with the heater on hot and with the rad-cap off to try and ger rid of any air already and all that happens is the water comes over the top of the header tank when it get to the higher temperature but no air bubbles come out so i presume there is no air in the system?
I was just concerned that the top pipes were getting hot and is this ok because other than this it seems fine.

TonyBurns

iTrader: (3)

Heat rises, but then again the cooling system should flow though the radiator, if the top is hot and the bottom is cold id say you may have an air blockage in there.

Tony

scubbydubby555

Tony how can i get rid of this?

davedipster

Drain it all out and fill it back up very very slowly.

E46_M3

personally I would run the engine(with the filler cap removed and the heater set to hot, heater fan off.. aiding warm up time)

constantly massage the top and bottom hoses, monitoring the coolant level in the header tank, untill the thermostat opens. Check that the heater is hot. You'll know when the thermostat opens as the radiator core will become obviously warm. This may also be accompanied by the coolant suddenly dropping or sometimes overflowing. Re-fit the filler cap and run to check that the cooling fans operate ok.. they should operate at approximately 2/3 to 3/4 of the temp gauge scale.

It doesn't hurt to pick the revs up from idle... gets the water pump impeller working away nicely

Remember to re-check coolant level once the engine has cooled.

In my experience the key has been to leave the cap off, allowing air to vent. Also worth checking that the vent pipe (thin pipe, on the radiator, next to top hose is not blocked! it has been known)

Also worth noting the bottom hose should be noticably cooler than the top hose

Just in case there is an issue with, for example the thermostat, be cautious and ready for overflow from the header tank

good luck