1992 Cadillac Deville Heater core problems

SEAN03

MEMBER
1992 CADILLAC DEVILLE
4.9L
V8
FWD
AUTOMATIC
136,000 MILES

High I have a 1992 Cadillac Deville. I had a flush and water in the cooling system. The heat ran hot it was nice on cold days to have heat. I drained the flush out and put antifreeze in the car and let it run and do its thing. I had the heat mode on in the car. It was blowing cold air. It makes no sense the heater core is brand new it is only a month old. I felt the big hose that connects to the water outlet that was hot. I felt the hose that connects to the tee it was the first one it was warm then I felt the hose that went down it was also warm then I felt the hose that connects to the heater core. It was cold. I felt the other hose that connect to the bottom of the heater core that was cold to. So both heater core hoses were cold. This makes no sense any suggestions on why it runs hot on water and not on antifreeze. I need my heat because it is cold this week where I live. Thanks.

1 Reply

CJ MEDEVAC

MECHANIC
11,004 POSTS

I'VE BEEN POURING OVER "MITCHELL I" AT THE STUFF ABOUT YOUR VEHICLE

I'M MORE OF AN OLD TIME JEEP GUY, SO I KNOW LITTLE OF HOW YOUR WORKS EXACTLY

OBVIOUSLY, YOU HAVE AIR IN THE SYSTEM, PARTICULARLY IN THE HEATER CORE LINE

I DUG DEEP, LOOKING FOR A BLEEDING PROCEDURE.I COULD NOT FIND ONE

. SO, 1ST THING I'M GONNA RECOMMEND IS. INSURE YOUR RADIATOR IS STILL FULL. IF NOT, GET IT THAT WAY!

I'VE SEEN ON OTHER VEHICLES----ELEVATING THEM ON A CURB---ETC AND FILLING THE SYSTEM WHILE IT RUNS SOMETIMES WORKS

. ANOTHER METHOD I'VE SEEN WORK IS TO INSTALL ONE OF THOSE "TEEs" WITH A CAP (FLUSHING KIT) IN THE RETURN LINE FROM THE HEATER CORE. SEE 1ST PIC (ADVANCE AUTO PARTS)

WHILE THE ENGINE IS COLD!----BUT RUNNING. YOU MIGHT LOOSEN THE CAP AND BLEED SOME AIR OUT

ONCE IT "CATCHES" JUICE---IT MAY CONTINUE TO CIRCULATE THE AIR INTO THE RADIATOR. AND THE RADIATOR JUICE INTO THE VOID IN THE LINES

SO BE SURE YOU FILL IT BACK UP, ONCE IT IS COOL!

I DO NOT WANT YOU TO DO ANY OF THE ABOVE INSTALLING OR BLEEDING WHEN THE ENGINE IS HOTI DON'T WANT YOU IN THE BURN CENTER!

I'M SURE YOU ARE LOST ON WHAT IS THE "FEED" TO THE RADIATOR AND WHICH IS THE RETURN (WHERE I WOULD INSTALL THE TEE)

"MITCHELL I" HAD ONE "TYPICAL DIAGRAM" I WILL POST IT AS THE 2ND PIC

ALL I HAVE LEFT IS A "REAL PICS" OF MY '77 CJ 5 SIX CYLINDER 258

(I ANSWER CONFIDENTLY IN THE JEEP CJ 5 AND CJ 7 FORUMS, THEY'RE MY CUP OF TEA)

THE FEED TO MY HEATER CORE AND OTHER HEATED ACCESSORIES, STARTS AT THE WATER OUTLET (NEXT TO THE THERMOSTAT)----THEN FEEDS MY STUFF. OUT OF MY STUFF, THEY COLLECT TOGETHER (NOW COOLER) AND FEED BACK INTO MY WATER PUMP

FROM THERE, THE COOLER WATER GOES BACK INTO THE HEAD TO BE REHEATEDTHIS IS THE CYCLE OF THE HEATER LINES

THE THERMOSTAT KEEPS THE "MY ENGINE" AT 195 DEGREES---IF IT GETS HOTTER---IT OPENS----HOTTER WATER GOES INTO THE RADIATOR AT THE TOP TO BE COOLED BY THE FAN

COOLER WATER FROM THE BOTTOM OF THE RADIATOR REPLENISHES THE ENGINE WITH WHAT JUST CAME OUT

I JUST WANTED YOU TO KNOW----HEATER LINES AND RADIATOR LINES SHARE THE SAME COOLANT----WORK SIMULTANEOUSLYIF FOR SOME REASON THERE IS A POCKET OF AIR---IT CANNOT BE "PUMPED" AS WATER CAN

HERE'S MY JEEP PICS---MAYBE THEY WILL AID YOU---SORRY I HAD NONE FOR YOUR RIG

. LAST PICS ARE MEANT TO AID A CJ GUY INTO ROUTING HIS ORIGINAL HEATER HOSES TO MAXIMIZE HEAT TO THE HEATER COREORIGINALLY THEY WERE ROUTED THRU THE INTAKE MANIFOLD 1ST, (HEAT LOSS) THEN INTO THE HEATER CORE, THEN TO THE WATER PUMP. IN A SERIES OR ONE BIG LOOP

MY METHOD IS MORE LIKE A STEAM SYSTEM, AS THE HOTTEST WATER FEEDS ALL FIXTURES AT ONCE---THE "USED UP" HEATED WATER RETURNS FROM EACH FIXTURE TO THE WATER PUMP

I INCLUDED THESE PICS SO YOU MIGHT UNDERSTAND THE FEED AND RETURN BETTER

RETURN TO THIS THREAD WITH GOOD NEWS!

THE MEDIC

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