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BASICS:
1. 1972 base 350. Totally stock
2. Timing at 8 BTDC, 30 degree dwell, 600 RPM in drive.
3. Starts great, runs great, idles great.
4. Fan installed correctly, shroud in tact, sealing foam in place, new thermostat, new coolant.
5. Gas mileage is kinda crappy…maybe 90 miles on a half tank.
6. However, its gets pretty hot…
a. Gauge is useless as it shows something like 160 when totally warmed up
b. Using an IR Thermometer I get a reading of 230 on the intake manifold and 190-200 on the upper radiator hose.
c. Thermostat housing reads same as the intake manifold.
d. Hot restart results in erratic idle and near stall, but when given more throttle runs fine.
e. Notice that the heater core hose touches the steel fuel inlet line…could be heating up the fuel? Vapor lock?
PLAN:
1. I have not checked TOTAL timing and the old vacuum advance may not be advancing the timing.
2. May eliminate the heater core routing. I'd hate to do that as I like everything to operate as intended. I could re-route the heater hose.
3. Maybe have the radiator rebuilt.
New thermostat bad 230 intake temp vs 190 upper hose makes me think this, collapsing lower hose while running not letting coolant through. Radiator clogged as mentioned before, reverse rotation water pump installed unknowingly? Air pocket in cooling system from recent installed parts? Any oil in coolant?
New thermostat bad 230 intake temp vs 190 upper hose makes me think this, collapsing lower hose while running not letting coolant through. Radiator clogged as mentioned before, reverse rotation water pump installed unknowingly? Air pocket in cooling system from recent installed parts? Any oil in coolant?
- Lower hose has intact spring and reads at 170 when car is fully warm. It could be collapsing.
- Water pump…hmmm…it is the original part. It could have failed I suppose.
- Air pocket is totally possible…replaced the heater hoses and drained off half the coolant. Also replaced the intake manifold and gasket.
- No oil in coolant.
- Radiator…seems to be the likely source, but I would like to eliminate the other possibilities too. So this is good stuff
I would go out and remove the radiator cap to check the coolant level. hopefully it is full. If not I would start the car cold and watch the level. Once the thermostat open it should flow pretty good while you add coolant. I use a lisle spill free funnel to get the air out.
Look for bubbles in the coolant.
I do not use factory timing specs. I have mine set to 14* at idle. More advance can help cool things off.
I have a 180* tstat. When I point a laser thermometer at the tstat housing it reads 180* and my gauge is right around 180 also so you are right not to trust the gauge.
I hope you get this one figured out before it gets to hot out.
Running hot around town suggests air flow problems, such as a bad thermo clutch.
At highway speeds (high load), suspect radiator efficiency as you should have sufficient airflow across the radiator.
This is the starting point for me. I like AC steel fans and thermo clutches. A good stock water pump will do the job; I've had good luck with Flow Kooler pumps.
I have the re-cored original Harrison in my L36.
- Lower hose has intact spring and reads at 170 when car is fully warm. It could be collapsing.
- Water pump…hmmm…it is the original part. It could have failed I suppose.
- Air pocket is totally possible…replaced the heater hoses and drained off half the coolant. Also replaced the intake manifold and gasket.
- No oil in coolant.
- Radiator…seems to be the likely source, but I would like to eliminate the other possibilities too. So this is good stuff
The water pump typically fails by springing a leak through the weep hole.
The impeller on the water pump could be ineffective due to cavitation erosion or scale buildup. Also, it doesn't take much scale to drastically reduce the thermal efficiency of metal, so depending on how diligent one has been replenishing anti corrosives in the coolant that could be an issue.
I have personally just switched to Evans waterless coolant after tiring of coolant flushes and replacing heater cores on old cars. Hope this helps...
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Originally Posted by sriser
BASICS:
1. 1972 base 350. Totally stock
2. Timing at 8 BTDC, 30 degree dwell, 600 RPM in drive.
3. Starts great, runs great, idles great.
4. Fan installed correctly, shroud in tact, sealing foam in place, new thermostat, new coolant. 5. Gas mileage is kinda crappy…maybe 90 miles on a half tank.
6. However, its gets pretty hot…
a. Gauge is useless as it shows something like 160 when totally warmed up
b. Using an IR Thermometer I get a reading of 230 on the intake manifold and 190-200 on the upper radiator hose.
c. Thermostat housing reads same as the intake manifold.
d. Hot restart results in erratic idle and near stall, but when given more throttle runs fine.
e. Notice that the heater core hose touches the steel fuel inlet line…could be heating up the fuel? Vapor lock?
PLAN:
1. I have not checked TOTAL timing and the old vacuum advance may not be advancing the timing.
2. May eliminate the heater core routing. I'd hate to do that as I like everything to operate as intended. I could re-route the heater hose.
3. Maybe have the radiator rebuilt.
Double check the clutch fan it should not spin freely
Can you feel the air movement engine side of fan ?
My GTO did this got hot stayed hot, I replaced everything.
Clutch fan was not enough air moving through the radiator
Need to know what your "all in" timing is, should be at or near 36 deg at 3000 rpm. ie vac advance disconnected and plugged. Full advance timing more important than static timing. "Tarded" timing makes for hotter running.
Just had a club member find his overheating problem after 30 years of trying by radiator, thermo, clutch fan, water pump replacements. At one point, the engine was rebuilt also. Turned out to be the vacuum advance. Easier to try than the radiator, though the radiator is the most important element in cooling.
Some great suggestions in the posts. I have owned two C3s including my fully restored '72 LT1 coupe so have learned a few things as well. First, all C3s can be subject to air flow and radiator issues. Since I planned to drive my '72 LT1, I had the original Harrison radiator with a high efficiency brass-copper core. These radiator cores are expense (about $300) but provide superior cooling capacity. I'm running a stock 180 degree thermostat and 38 degree total timing, and the coolant temp has never reached 200 degrees (even in hot weather). I'm also running the original fan clutch and a seven blade steel fan.
your basing everything off of unknown temperature, fix the gauge, then trouble shoot cooling problems,
I verify temperature gauge by removing sending unit, from car.
use a long 120v ext cord....... "DO NOT PLUG IN !"
add a couple jumpers, use 1 ext. cord conductor for gnd going to your sending unit, use the other conductor for gauge feedback,
make connections at stove and car, setup on the stove, in pan of water, turn everything on, boil water in pan with sending unit,
your car gauge should be 212 degrees F at boiling point.
your gauge is now verified reading correct temperature, ...if not get the correct sending unit.
your basing everything off of unknown temperature, fix the gauge, then trouble shoot cooling problems,
I verify temperature gauge by removing sending unit, from car.
use a long 120v ext cord....... "DO NOT PLUG IN !"
add a couple jumpers, use 1 ext. cord conductor for gnd going to your sending unit, use the other conductor for gauge feedback,
make connections at stove and car, setup on the stove, in pan of water, turn everything on, boil water in pan with sending unit,
your car gauge should be 212 degrees F at boiling point.
your gauge is now verified reading correct temperature, ...if not get the correct sending unit.
Water boils at 212 degrees F at sea level. If you live in Denver water will boil at 203 degrees F.
Easy way to check the radiator. Warm it up. Turn it off. Reach in and feel the bottom of the radiator and the top of the radiator. If clogged. the bottom will be considerably colder. If clogged you will be able to hold your palm on it without burning yourself and won't with the top.
Running Too HOT! Ideas?
