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.

[donthekawguy]

If the top hose is hot and the bottom cold you aren't getting water flow. Try taking the thermostat out and stick you water hose in the hole to try and force the air out of the block. The put the housing on and run it and squeeze the top hose while it's running with the cap off. It might take a while but should do the trick. If not pull one the heater hoses off and start it to see if you have water flow.

[luvbowties]

..." I'll dl all the burping vids I can and get at it in the morn."...


Hello, smo_king, why don't you try a trick that sometimes works. Have engine cool with ALL the coolant drained completely. Shut all petcocks & have all hoses attached. Remove the ENGINE END of the TOP HEATER hose.

Holding the now free end ABOVE the height of where that top hose attaches to HEATER, use a funnel and slowly pour water into the end of that heater hose. When water begins to flow out of the hose fitting on the engine, attach the free end you have been pouring water into and clamp it tightly. Then, top off the radiator thru the radiator cap opening.

Now try running engine, checking temps & heat at various places. **The lower rad. hose is from where the pump pulls cooled water to pump into the engine. The heated water from the engine flows thru top hose and into top of radiator. The top part of the rad. & its hose should get hot; and lower part of rad. & its hose should be RELATIVELY & NOTICEABLY cooler.

Almost forgot: Rock Auto, or Advance Auto may have new heater cores for 45-50$.

HTH,
sam

[ERASER5]

Stick with the 13lb Rad cap. The higher pressure will only increase the boiling point of the water, it will not change your overheating problem at all. What the higher pressure WILL do is push on your old radiator more. That is not so good.

[Smo_King]

Tried a few things no luck. Heater was getting up there tho. First time its broke *60. It got to bout *84 at core from inside. Off to the parts store to double down...

Originally Posted by luvbowties

Remove the ENGINE END of the TOP HEATER hose.Now try running engine, checking temps & heat at various places.

I filled the whole system the first time that way.

Grabbed a *180 therm and 7lb cap. Backed down the 24* driveway with new items installed. FIlled via heater hose and topped off inbetween runs. Ran, stopped, ran, stopped. Checking temps inside and out.

I did not overheat in 5-8 min runs with 20 min pauses. Heater up to *104. Headers reading lots lower still higher on left center *330 vs *260.

Guna let it sit nose up over night then give it a good 10-15 min run tmoro. Think she finally got there with the heater reading *104 on second run that should mean circulation right?

Heater core upper *116 lower *94 at copper fitting.
Therm opened at 167/172 outside at connector and temp sensor.
Bottom rad in *74 top in *90-104.

Originally Posted by ERASER5

Stick with the 13lb Rad cap.

Grabbed a 7lb. Yeah I got wrong numbers/parts at auto parts shop. Told me 195 TS and 13-16 rad cap...

Thanks for all the help guys! Happy Thanksgiving to all!

[luvbowties]

Originally Posted by Smo_King

Tried a few things no luck. Heater was getting up there tho. First time its broke *60. It got to bout *84 at core from inside. Off to the parts store to double down...



I filled the whole system the first time that way.

Grabbed a *180 therm and 7lb cap. Backed down the 24* driveway with new items installed. FIlled via heater hose and topped off inbetween runs. Ran, stopped, ran, stopped. Checking temps inside and out.

I did not overheat in 5-8 min runs with 20 min pauses. Heater up to *104. Headers reading lots lower still higher on left center *330 vs *260.

Guna let it sit nose up over night then give it a good 10-15 min run tmoro. Think she finally got there with the heater reading *104 on second run that should mean circulation right?

Heater core upper *116 lower *94 at copper fitting.
Therm opened at 167/172 outside at connector and temp sensor.
Bottom rad in *74 top in *90-104.



Grabbed a 7lb. Yeah I got wrong numbers/parts at auto parts shop. Told me 195 TS and 13-16 rad cap...

Thanks for all the help guys! Happy Thanksgiving to all!

Hope you have it fixed. But one thing is strange. With a 180-degree t'stat, it should not open at LESS than 180 degrees, but at something higher, like 190-195. Also, I'd re-check proper specs for the correct pressure cap. Your '62 may be different from my '66, but IIRC, the '66 calls for one somewhere near the range of 13-16 lbs.
HTH,
sam

[luvbowties]

I re-checked myself. I'm finding conflicting info on which is correct, 7ish or 15ish, but leaning toward 7-lb.--got me wondering if the 15-lb. on my '66 should be lower.(?) Regrets.
sam

[Smo_King]

Thanks. I was guna chk the manual after the games as well. As something is causing them all to be inccorect at O'rileys so far. Prolly dif in 1000/1500/3500. But my oil element , cap and therm were all dif than what store called for.

Wana say the oil element was wix xx511. They gave me a CH33APL.

I pulled the 13 thought it called for 13-16 asked for a 14 got the 7. Then asked how much each pound effected the boiling point? He said it didn't so I just left.

The readings are from outside of engine with IR gun.
Posted via Mobile Device

[padresag]

to bleed the heater. pull the return heater hose off at the heater while it is running until water comes out and put it back on. or one can always drill a few 1/8" holes in the face ot the thermostat. just a small bypass
ron

[Smo_King]

[padresag]

Originally Posted by Smo_King

Thanks. I was guna chk the manual after the games as well. As something is causing them all to be inccorect at O'rileys so far. Prolly dif in 1000/1500/3500. But my oil element , cap and therm were all dif than what store called for.

Wana say the oil element was wix xx511. They gave me a CH33APL.

I pulled the 13 thought it called for 13-16 asked for a 14 got the 7. Then asked how much each pound effected the boiling point? He said it didn't so I just left.

The readings are from outside of engine with IR gun.
Posted via Mobile Device

believe that the ch33apl was for a chev. you have to tell them what eng you have and if they argue, cuff em on the side of the head. orig p/cap was 7lb. if you system can handle the 13 lb cap then it is fine to use. for every lb of pressure it will raise the boiling point 3 degrees . a 7lb cap will raise it 21 degrees. a 50/50 mix of ethylene glycol will raise it another 18 degrees
ron

[luvbowties]

If we can believe Advance A/P, I think they show only 7-lb for the '62(all engines) and only the 15-lb for the '66(all engines). Go figure? And my lookup in O'Reilly's? they safely avoid revealing ANY psi-ratings, only part nos.; maybe theirs is "automatic & 'self-sets"!!! Some other sites are conflicting.
sam