62 GMC Heater Water Pump Cooling issues.

[Smo_King]

Ok held out long as I could... 62 GmC 305v6 LWB

Heater does not heat. Taken apart, flushed core, etc... on to, think my pump is out?

Replaced thermostat from 180>195
Flushed system took all hoses off replaced hoses and new fluids.
Burped her best I could water just over flowed out cap.
Coil is in the bottom hose.
Belts ok and pulleys all turn.
Fan works.
New oil and filter.
No noticable weepage.
Radiator appears to have been replaced. Guessing in 98ish. Its only been 15 miles since 98-99
Cap seems ok 13lbs going to get a 14-16 next week.

This all started after pulling hoses to chk heater core and connections. Will overheat idling in about 5mins (or get to H) Guage is OEM, Cleaned contacts and assume guage and temp sensor are somewhat correct. IR after running then shut off near therm area outside, reads 190ish.

-I pulled the heater hose from thermostat area which I assume is out and started engine and reved, and nothing came out.
-There was significant calcium but no chucnks of rust when I flushed system. -Water is really hard aound here. Thats all I got.
-Radiator appears to have been replaced. Guessing in 98ish. Its only been 15 miles since 98-99

Can I get lucky and pull pump and unclogg?
Does heater have a thermostat as well?
Is this short or long? And whats the cheapest way to replace for now, rebuild kit, another model anything in the 20-30 range? I dont have a press but pretty sure a neighbor would.

[HEI451]

It may be that the impeller inside the water pump is either broken, or loose on the shaft. That would let the shaft turn freely, along with the fan and pulley, but not flow water adequately, if at all.

It takes a good 4 to 5 minutes for the 65 V6 305 in my 64 C30 to get to ops temp, I use a 180 deg/F thermostat, so, I think I'd pull the water pump, or figure out a way to stop the impeller from the outside with some sort of dowel, screwdriver, and see if it was still firmly attached to the water pump shaft first off. The impeller is simply pressed onto the shaft.

Go from there.

[donthekawguy]

If it overheats that fast I would guess it needs to be burped more. The air in the motor will heat up faster than the water even if the impellar on the pump was not turning it would still take a while for the water to get warm enough to open the thermostat.

[rcbildr]

Do you have an extra gage (or access to one) to hook up and actually see if your factory gage is off?

[luvbowties]

Originally Posted by rcbildr

Do you have an extra gage (or access to one) to hook up and actually see if your factory gage is off?

A useful tool is a cooking thermometer from the grocery store with a long sensor stem, I'd guess around $10 now. Only drawback is you must have cap off to test temp, but otherwise quite handy & relatively accurate. HTH.
sam

[Smo_King]

pump looks fine? cleaned it up, no wobble. installed a new therm 195* with hole. pulled the radiator, cleaned it, back flushed it a few times runs clean both ways. re flushed heater core again as well. no issues there.

overheats still. ran about 10-15 till it overheated this time. heater finaly bumped up to *76 at core cover, first time its broke *60... Therm opened a few times, topped off when it did. Bottom hose, water and rad at bottom remained cold.

readings of 210-220 at therm, 280-300 at mainfold, 160 on oil filter.

Guess I will try timing tommorow. It backfires now off initial throttle out the carb then clears and runs smooth. Not every time.

Are ther any electrical issues that could be the prob? Oil pump?

Originally Posted by donthekawguy

If it overheats that fast I would guess it needs to be burped more.

Hoping this is it at this point. Since this all started when I cleaned the heater core to begin with. I figured the hole in ther therm would make burping less of an ordeal. Guess not? afaik ther is no flow still that I can tell. I'll dl all the burping vids I can and get at it in the morn.

Originally Posted by rcbildr

Do you have an extra gage (or access to one) to hook up and actually see if your factory gage is off?

Not at the moment. But the infrared readings should be close to internal at most points I would think *10-15ish off?

Originally Posted by luvbowties

A useful tool is a cooking thermometer

I have one, I'll try in the morning as well.


Thanks all! Get back on the horse tommorow. So close to buttoning back up after the doing the fresh buy routine. Been at it nonstop for a month now.

[Smo_King]