DarkJuggalo

iTrader: (6)

Car is a 2006 Pontiac Grand prix, 3.8L non s/c. Heat stopped working, on low you get a little bit of heat but on high you get cold air with pockets of warm air. Top hose to heatcore is hot, lower one is cold. Top rad hose is hot by t-stat, by rad it is cold. Can feel movement of rad fluid in all hoses, both rad hoses changed 2k miles ago, no wetness under dash near heater core. Any ideas plz

doublea87

iTrader: (16)

there could be a couple different possiblities on this one. 1) could be a clogged radiator 2) possible clogged heater core, try back flushing the system 3) water pump blades are damaged and not spining.

how many miles on the vehicle? also check for an lower intake leaking as those are notorious for them

DarkJuggalo

iTrader: (6)

yea i checked the intake when i read that online, its not the plastic one its the aluminum and no leaks. how would i go about back flushing the system?

i was going to change the water pump a few months ago when the car tried over heating, but after changing the upper/lower rad hose it worked perfectly fine.

VandykeT/A

Maybe air in the system.

DarkJuggalo

iTrader: (6)

no air in the system

DarkJuggalo

iTrader: (6)

well atleast i dont think there is, i let it idle for almost an hour and no bubbles before i put the rad cap back on

DarkJuggalo

iTrader: (6)

checked again today, no air in the system. any ideas?

DarkJuggalo

iTrader: (6)

is there a sure fire way to know if it is the waterpump or a clog? i cant seem to find a backflush kit local

eseibel67

iTrader: (10)

My bet is on air in the system since you have the systems of air bubbles at the heater core AND the rad.

Jack up the car on the front right side as as high as you can get it. Not sure if this car uses a bypass valve on the heater hoses, but just to be safe, blast the heat settings all on full blast. Start the car and get it just hot enough that you can still get the rad cap off. Massage the upper rad hose with force to try to burp the air out the rad cap hole.

Play with that for a while, then put the cap back on, let it pressurize, and see if you get any heat.

DarkJuggalo

iTrader: (6)

There is also a Bleeder Valve on top of the Tstat housing, someone just pmed me and told me to close rad cap and get car to full op temp and crack that bad boy and stand back until only rad fluid comes out. ill give that a shot in about 15 min or so. Keep the ideas coming plz

eseibel67

iTrader: (10)

Didn't know you had a bleeder valve. That makes it way easy.

DarkJuggalo

iTrader: (6)

it makes it easy when the 7mm bolt doesnt break in the valve trying to undo the damn thing

doublea87

iTrader: (16)

ouch that suck the bolt broke! i wasnt sure if it was the plastic intake or aluminum, dont remember what year they switched over.

back flushing is easy to do just need a hose. disconnect the 2 heater hoses on the engine side, NOT the connections on the actually core and run a hose in the opposite direction of flow.

however i would try getting every bit of air out first like the other gents are saying.

DarkJuggalo

iTrader: (6)

well i got a brass bolt to replace it, i undid it with the car running not much air came out, then fluid barely came out, kinda just flowed up to the top and stopped. should this thing be under serious pressure? cause the pressure is very weak. i changed the t stat again, and now the upper rad hose is hot on both sides not 1 just, however still no heat, no air in the system, and upper core hose is hot, lower still cold.

DarkJuggalo

iTrader: (6)

any easy way to determine bad water pump?

Carter01

iTrader: (11)

backflush it 100%, then jack up the front of the car as you refill it and it will burp, then use the bleeder valve to get the remaining air out.

I wouldn't go any farther until I backflushed the car... seen it happen before, very easy fix.

DarkJuggalo

iTrader: (6)

is it called something other than a backflush kit?

Carter01

iTrader: (11)

It's really not a kit per say. You can disconnect your lines from the heater core and get a water hose and spray it backwards through the lines. there will probably be allot of gunk that flushes out. Reinstall the lines and try it, normally it works and it's free so it can't hurt.

DarkJuggalo

iTrader: (6)

i found the kit, its called a Cooling system flush kit. the guys at the autoparts stores i called obviously were too lazy to type. i will be trying this tomarrow. i am still questioning it though, if u push it out of the heater core, through the block, through the rad and out(hopefully) how do i know it isnt just gonna clog up in the block or rad. makes me a tad nervous

Carter01

iTrader: (11)

Not exactly sure how your car is routed but you are not pushing anything back through the block, just out of the heater core. Disconnect both line to the heater core and flush out just the core. I can't picture how your car is setup but most setups will allow this to happen.