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no heat


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imlost
New User

Jan 13, 2008, 2:17 PM

Post #1 of 2 (1735 views)
no heat Sign In

hello and thanks for the help first thing...we have an 89 chevy astro V6 2.8 with about 50000 miles on a rebuilt engine...we at the moment are working on it cause we have no heat...we cant seem to get the the heater core to get hot water to help generate heat...we took off the heater core to make sure we were getting good flow through the core and that test seemed to work as we got water to flow through it while it was off....while the core was disconnected we also checked to see if we were getting flow thru the connecting hoses...we kept putting water in the radiator and started the motor and watched to see if we were getting water to the connection..what we got at the connection was water would pulse out along with air so we thought maybe we didnt have in enough water ..when we hook it all back together we noticed that the hoses to the heater core were not getting hot at the last segment of connections...the connection from the backside of the engineblock to the last segment get hot but doesnt seems to go any farther that that...we also have been filling the radiator and reservior up thinking we didnt have enough water to get good flow through the motor but we think we have put in plenty of water....we also hear gurggling when we turn the motor off like the motor is sucking for water...and then we fill the radiator back up again...we also put on a new thermostat on as the first check on the no heat issue...we think the thermostat is working as we can feel the upper hose from the radiator lose pressure (as in we can squeeze it) when the water flows into the block...so we have two questions...1.. should we be able to squeeze the upper radiator hose when the thermostat opens and water flows into the block until the pressure builds back up...and 2....is there a cause for us not getting the last connecting hose at the heater core to heat up...again thanks so much for helping

imlost


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jan 13, 2008, 10:37 PM

Post #2 of 2 (1731 views)
Re: no heat Sign In

At the moment it seems like it's not completely full of coolant - water ok for testing but don't leave it with just water.

With engine cold and everything hooked up the radiator must be full at the radiator. Thermostat can lock air in the engine so it not conclusive just yet. With it full and reservoir in range, radiator cap back on, start the engine for warm up. Upper hose should be cold and stay cold and unpressurized for a while. Watch temp gauge, run heater and as engine warms up the upper hose should build up some pressure and slowly get warm then perhaps too hot to touch.

Thermostat has opened and trapped air should purge out to radiator. Let cool enough to remove the cap again (at radiator) and it may be low again. Fill again and repeat. When you are convinced it's full enough and temp gauge stabil drive it around a bit and check again.

For whatever reason still a possible problem the air in the system is the first thing to get known filled and air locks out.

System will build pressure from the expansion of coolant and should pretty much stay under pressure till it cools down. If you notice the pressure by feel is very quick to build up then we have a potential problem to solve/diagnose.

There have been reports right here of water pumps that corrode and don't pump water around well and until I came to this site about five years ago I'd never had that happen to me and don't know the 2.8 to be amoung some mentioned.

Start with that and let's roll from there,

T







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