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radiator over flow?

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radiator over flow?

evilokc evilokc
User | Posts: 81 | Joined: 07/10
Posted: 02/27/13
08:00 PM

this is a newb question and i feel silly for not knowing but here we go. i noticed my radiator is  spewing out the top tube that should be connected to an overflow but isnt. can i just plug that? its making a mess on my motor and im losing more fluid than i think i not really sure what the function of an overflow is. is it to relieve pressure? if the radiator spews fluid into the overflow when its hot does it create a vacume that pulls fluid back into itself when it needs it or does it just sit in the overflow until i empty it?  

waynep71222 waynep71222
User | Posts: 106 | Joined: 04/12
Posted: 02/27/13
09:27 PM

a few things...  

with the engine warmed up..... does the cooling system hold pressure???

squeeze the upper hose... got pressure.. or does the system just blow out the overflow and  pull back in when you release the hose...

it should hold pressure..

take the cap off.. look at the disc in the middle of the rubber seal.. is it spring loaded against the rubber...

all current conventional caps are coolant recovery type... there are special caps but they are not the usual shape..

what pressure rating you need depends on how big the TOP TANK is..  if you have a HUGE TOP tank or a big surge tank.. you will want a 7 PSI cap... medium size tanks can use a 13 PSI cap.. small tanks can use a 16 PSI tank...

this is to prevent blowing the tank apart  with pressure build up..

are you running a proper temp thermostat..

are you running a bypass hose or circuit somehow.. so the coolant will circulate from the pump into the block.. up into the back of the head.. forward thru the heads to the coolant crossover and the thermostat... where its blocked by the closed thermostat and forced thru the bypass hose back into the water pump making the trip many times until the coolant temp is warm enough to open the thermostat... then some circulates into the radiator displacing the cooler coolant there..  this cooler coolant circulates in and closes the thermostat.. allowing the coolant in the radiator to completely stop so the fan and ram air thru can cool it...

this prevents run away cooling systems..  where it takes forever to get warm.. then gets hotter and hotter as you drive along the freeway.. until it overheats as the fan and ram air cannot cool the coolant that is flowing at high speed thru the radiator...

lets talk about the need for a coolant recovery bottle..

the coolant expands  in the cooling system... since radiators work best when all the cooling tubes are filled... so the coolant expands and pushes past the radiator cap... into the bottom hose of the coolant recovery tank..   when you shut down.. the coolant cools and contracts pulling coolant from the bottom of the recovery tank into the radiator to keep it full...

you can get all kind of coolant recovery tanks..

there are also expansion tanks available.. that work in a similar fashion... and can be mounted out of the way.....  

evilokc evilokc
User | Posts: 81 | Joined: 07/10
Posted: 02/28/13
01:50 PM

thanks for the info. to be honest im going to have to get in there and see what the set up is. the motor doesnt take long to warm up and the temp stays in a very good range. i just noticed that when i run it for a while and then park it the radiator pukes a bit. makes me nervous.  

evilokc evilokc
User | Posts: 81 | Joined: 07/10
Posted: 03/02/13
12:08 AM

okay i used all of your knowledge and.....i have a leak in the lower hose. i thought it was spewing out the radiator because it was getting on the top of the motor but its a small leak in the lower hose that seems to open under pressure and squirts onto the fan which flings it everywhere.. so im replacing the hose. you guys are great though. i love places where we can all share knowledge and experience.i need all the help i can get.