Do I need to preload the heater core?

toddr124

toddr124

Hagerstown, MD
Installed the heater core last night and ran the car up to temperature. The water got hot, the radiator got hot, the heater hoses in the engine bay got hot, the heater core stayed cold. The heater hoses in the passenger wheel well were also cold.

Do I need to uhook the heater hoses in the engine compartment and run water through the heater core and than hook the hoses to the engine again or is there a simple way I am missing ? I did bench test the heater core for flow and it did fine.
 
Could be a stuck heater valve

No pre-load necessary but the valve should certainly be open.

That aside, your heater hose starts at the (approx.) 3/4 I.D. tube that spans from your water pump, then returns to the right rear side of the engine just above the snail mount.

You can unhook it at these 2 points and flush it both ways if you want.

Good luck!
 
Did you.

Rev the engine to force the coolant to the heater core? The cores with A/C had a bleeder on them as well, a 10mm bolt that can be seen from the passanger foot well.

Rev the engine and see if heat blows from the core if not you have an air lock.

TonyK.

Grimsby Ontario Canada.
 
TonyK said:
Rev the engine to force the coolant to the heater core? The cores with A/C had a bleeder on them as well, a 10mm bolt that can be seen from the passanger foot well.

Rev the engine and see if heat blows from the core if not you have an air lock.
.
Click to expand...

I revved the engine for a few minutes and nothing changed. The fluid level in the expansion tank never went down. I must have an air lock. I will try to preload the core tomorrow.
 
Stupid question

toddr124 said:
I revved the engine for a few minutes and nothing changed. The fluid level in the expansion tank never went down. I must have an air lock. I will try to preload the core tomorrow.
Click to expand...

Hi Todd. I hate to ask stupid questions, but did you check that the heater valve is functioning? I will assume the valve is fine since you wouldn't put a new core in without checking the valve, but are you trusting the lever operation? Did you get down there and look to be sure that the cable is attached to the arm and it is actually opening and closing the valve?
 
Checked the valve, core and lever

I flushed the replacement heater core with water and found the valve did not close completely. I removed the valve from my blown core and swapped the valves. Tested the valve and core together. The lever is moving when I move the cable.

The heater hoses on the spark plug side of the engine did not get hot, only warm.
 
There IS a possibility that

the nipple that comes off your water pump extension pipe is clogged.
Only way to know that is to remove and inspect. Sorry, it's a P.I.T.A. job to do. :blackeye:
 
You wrote, "The heater hoses on the spark plug side of the engine did not get hot, only warm."

Get one of these at Lowe's Depot:
045734999909


Take the heater hose off of the nipple that comes out of the rear of the head right next to the snail mount, fit the barb in the open hose and clamp. Screw your garden hose onto the female fitting.
IMG_1183-1.jpg


Remove the heater hose from the nipple on the pipe that comes out of the back of the water pump.
IMG_1161-1.jpg


Open the heater valve and turn on the water, water should soon be flowing from the hose removed from the water pump pipe. In this direction I think you are backflushing.

Unclamp the barb from the hose up by the snail mount and put it into the hose removed from the water pump pipe nipple to check flow in the operational direction. Take care the hose effluent does not gush all over the alternator or other sensitive areas.

While the heater hose is removed from the water pump pipe, check for obstructions as Bob Brown posted.
 
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