Thread: Coolant not circulating

Originally Posted by Epic_Dragon

Have bled coolant system several times since ive owned it thats what i knew them as, top hose and return pipe but wasnt sure if one was also known as a bleed hose/pipe. I do raise the expansion tank when bleed the system. Im not sure how an airlock would form though all of a sudden if that is the cause. Unless is indeed a blockage somewhere caused by the red coolant crusty stuff.

Hi Epic Dragon,
This may sound silly, but simple ideas often do (at first).
When you have been bleeding the cooling system, has the car been on level ground?
If on a steep slope and the car is facing uphill, raising the expansion tank may not be enough to clear trapped air when bleeding.
I really don't think the "red coolant crusty stuff" is at all to blame - it only forms when coolant evaporates, which will not be happening within the cooling system.
May I ask - when you bleed the system, do you have the engine running?

Maybe Epic is dead right and the coolant isn't circulating. Maybe its time to remove the water pump and/or lower hose and look for obstructions, like sleeves fallen out of radiator hose branches.

So far we haven't heard if coolant is circulating.
With the cap off, is the bleed off port in the header tank flowing?.

Air lock: - straight up if it has been bled you can only have air getting in the system from a failing failed gasket. The scope of failure is academic and the recent replacement unfortunate.
A full header tank to use is indicative of the above even after a poor bleed process.

A crook thermostat will give you the symptoms described getting warm. It only takes a few degrees late opening.
However, It will not create sir in the system or an airlock......unless it's got too hot and the gasket has failed...return to above.

coke bottle bleed and infared spot thermo all the parts during warm up, you'll soon find the issue

Well since re bleeding, took ut for a drive with no issues? Heater is also working. Thermostat is a genuine one too. It does seem to be circulating coolant. And bleed with header tank raised on level ground. And engine is running. I didn't think it could be bled without engine running as it wouldn't be circulating? When i first bled it even though level was correct in expansion tank, there was no coolant coming out of the bleed hole. When the heater blew cold the top hose was also cold. But it was fine yesterday for a roughly 50km trip. i still believe it is thermostat and now it is unstuck. I do not believe it is head gasket. I couldn't see if rpm madw water shoot out of bleed hole as was doing it on my own. So will be repeating process with my partners help this weekend.

good to hear its working now , sounds like you had an airlock , possibly due to coolant loss , thats why i asked in my first post about stains , also re the telltale ,they can block up (this is also called bleed off port etc ) its just below the radiator cap and should have a small stream of coolant coming out with engine running , if not you can try clearing out the port with small gauge wire with engine running or compressed air if not running (carefully with both ). I wouldn't be changing the thermostat just yet . It might pay to get a pressure test , but this won't pick up things like fuel cooler o rings , so a visual check as well . If your head gasket was failing you would see bubbles in the expansion tank.
cheers