Hi,

My car (1996 Honda Accord 2.2L4-cyl Automatic) currently overheats very quickly. I posted on here and it is somewhat related to it:
https://www.hondaaccordforum.com/for...-change-50343/

To recap: My radiator cap had the middle plastic part break off (probably went into the coolant system), installed a new one. I then had the heater hose blow out, I replaced it. A few days later the top part of my radiator cracked and blows steam and coolant out. I realized that the coolant is flowing into the engine from the radiator (hose is hot and feels like theres coolant going in, but its not returning to the radiator:


Red: Hot. Green: Cool, I don't think its flowing back to the radiator..


My friend that helped me replace the hose was thinking that the plastic part probably went into the system and messed up either the water pump, or the thermostat. I don't know enough about this to figure out where to start.

Can anyone give me some probable things to try to figure this out?

 

this happened to me. does your car heat work? mine got stuck in the heater bypass valve.
i got a plastic male-to-male connecter and bypassed the bypass. not really a proper fix, but its a place to check.

 

Do you think that clogging the heater core bypass would cause enough pressure to blow a hose, then crack the plastic top of the radiator?

At one point the heater was blowing cool air. But after I fixed the hose it worked fine.

I just filled it up with water. I let it run a while, drove it around the block and it seems like its flowing better. Heater works fine. Now, I am afraid if I patch the crack or get a new radiator it will just blow something else out.

I think the plastic piece is in there still. Is there a simple way to tell if the water pump is working? or if the thermostat is having problems?

 

I don't think the water pump would be damaged by a small piece of plastic because the WP impeller is made of steel and driven by the timing belt. The plastic would either be chewed up by the pump or, more likely, sent on its way. It could easily get lodged in the thermostat housing though. Might be worth the peace of mind to just replace the thermostat. It's cheap and fairly easy to replace.

The piece of plastic getting stuck in a heater hose, valve, or core wouldn't cause any overheating problems. By design the heater valve stops any flow with no ill effects.

 

You got the arrows in the wrong direction. Hot water comes out of the engine flowing towards the top of the radiator. After flowing down through the radiator, it returns through the lower hose back to the thermostat.

Not sure what broke off your radiator cap, but it's probably trapped in the upper tank of the radiator. It's gotta be pretty small to go into one of the tubes of the radiator core.