Not sure how to phrase radiator hot one side, cold other

Hey I've had trouble with my zzr250 overheating so i thought i'd drain the water out of the radiator and put new coolant in, the old coolant smelled awful too, kind of rotten, burntish.

so I put new coolant in and cleaned the reservoir out, and then idled the engine for 5 minutes, to see how it went. the temp stayed very low, the needle only moved up a fraction of a millimeter, so i thought, sweet.

but as i was spraying hose water over the engine to clean off the mess i made, i noticed heaps of steam coming off the right hand side of the bike engine. I sprayed more water over that side and touched the radiator pipe and side near where the radiator cap was, and it was really hot, steaming hot, I mean i could touch it, but when i went around to the other side of the bike, where the pipe goes from the bottom of the radiator to the engine, it was quite cold.

Is that normal? Is that what a radiator does, take hot water from one side and make it cold out the other?? Or have i stuffed the thing up somehow, i was pretty careful not to get dirt in it, and i flushed it through with a hose and it seemed to gush out the other side ok.

help!!

Did you bleed the cooling system after filling it? sounds like you might have an air lock in the system, or your water pump might be shagged.


Neil

or
It may have not got hot enough for the thermostat to have opened so the water wasn't flowing thru your system. ?

actually after a bit more of the engine running the other side did get warm, hopefully that will do the trick.

Oh holy crap, water pump?? Bleed?? well not really i dont think i bled it, i disconnected the rubber pipe from underneath the radiator and forced hose water down the top where the radiator is until it came out clear at the bottom and the reservoir came out clear and overflowed, then i put the hose onto the metal part that runs into the engine and squirted all that out. then i filled it up with coolant from the top until it came out the bottom and ran the engine for a while after i put the hose back on...
i'll go do some researching on bleeding then thanks

sounds like the water needed to be changed and the thermostat hadn't kicked in yet. you can test the thermostat by dropping it in a pot of water on the stove and once it reaches boiling point it should open up.

protip: if your going to be testing this with a pot you ever intend to use for food again/your missus is about, make sure you clean any shit off the thermostat first.

[edit]afterthought: it sounds like it is still worth checking the water pump to make sure it isn't shagged either, this can be done by taking the hose off the inlet to the water pump and havign a look with a torch.[/edit]

make sure u bleed it, cause if you get air pockets trapped in the motor itself (this more so applys to cars with large cooling systems) but if it gets trapped it can over heat and blow HG also..

From what others have said i think is the issue!