I am having a strange problem (or problems) that I can't seem to figure out. 67 430 engine in a 67 Special. When I bought it last year I noticed it would run cool at night (around 150) and I found it had no thermostat. Put in a 180 t-stat and it seemed good in the warm weather, still running under 180 though. Now that it's cold, the car only gets up to about 150 degrees, according to the autometer electric temp gauge. Sender is in the intake manifold (edelbrock performer BBB) right next to thermostat housing. Stock rad, centrifugal clutch fan. Now I wouldn't mind it running so cold, but on days where it's maybe under 40 degrees out, I barely get any heat in the car. It's luke-warm at best. Things I already checked: Heater control cables are all connected and seem to be working right. Temperature door sounds like it slams shut on HOT, slams open on Cold. I took the cable off and the temp door does seem to fully close (best I can tell without going into the heater box). All radiator and heater hoses feel quite warm to the touch, but not really hot. Confirmed thermostat was working in a water pot on my stove (started opening around 175 i think). Then I replaced the thermostat with another 180 and same result. Coolant level is full in radiator. I'm stumped at this point. Any ideas on what else to check? Or is this normal? I never had a car that ran cooler than the thermostat rating.
Sounds like someone else had trouble too and thought removing the t-stat would help. Is the clutch fan operating correctly?
What is the ambient temp? My car runs 180 in the summer and right now only goes to 155-160. I still get heat though.
My 430 always ran on the cold side, only got on the right side of the temp gauge in gridlock traffic on a 120-degree summer day. I run an 195 thermostat, having a higher temp thermo can actually improve cooling by keeping the coolant in the engine longer. Is the original plumbing from the manifold to the heater core intact? There's a vacuum valve on the intake manifold which opens when the heater/defog is activated. If it is, and nothing is leaking, then perhaps the heater core is plugged up and only a trickle of hot coolant is circulating. Do all of your vents blow strong from the blower? You have decent airflow, it's just not that hot?
Hotter spark plugs may help a little? I have a vehicle that runs really cool in the winter as well and I have to block half of the radiator with cardboard for it to warm up, works. Just remember to remove for the hotter months. GL
All I know about the fan is it is a centrifugal clutch, and I think the original style was a thermostatic clutch. Ambient last night was probably 25-30, and the temp gauge said about 150-155. Barely any heat. Air flow seems good. I doubt the plumbing is original, there is a fitting on the manifold but should there be a separate vacuum line to it? I don't see that. I'll see if I have a picture of it.
Could it be an air bubble in the system, that is causing the coolant fluid level to be low? Just grabbing straws here.. Had that problem in a newer car.. Wouldn't make heat in the cabin, and was running cold in the winter time. Had to park it with the nose up on a hill, and run it hot..
I don't know what's causing it to run cool but even with 150 degrees you should be getting heat. I didn't get heat because my heater core was plugged up with rust. That was a fun task.
I did suspect that I could have two issues going on. I'm going to try to flush the heater core if it warms up above freezing anytime soon.
Heater core probably plugged, and as suggested, either put a higher temp T-stat in it for the season or cover the radiator with cardboard. My F100 is the same way, and I just block 3/4 of the radiator every winter. If you're going to go on a long road trip, remove the cardboard before taking off, because after a while at highway speeds it'll most likely get warmer than you want.
Not present on this car. If i Find the time this weekend I’m going to attempt to flush the heater core and put a hotter thermostat in it.
What I would do BEFORE taking ANYTHING about. Let the engine warm up to it's highest temp. Turn the heater fan on medium. Feel the inlet hose for the core & the outlet hose. After running for awhile both hoses should feel pretty close to the same temp. If the return feels much cooler than the inlet the core is probably somewhat clogged. Flush backwards from outlet to inlet with a garden hose attached to outlet. Turn on water, slowly at 1st, & as it cleans/clears out turn the pressure up until it's flowing freely. DON'T turn the pressure up immediately as if it is somewhat plugged it can cause the core to start leaking. Then put an air nozzle to it, slowly at 1st, & blow it out. IF rust came out flush again with water. IF it was clogged/partially clogged it will end up being hotter. Gotta start with basics BEFORE replacing/chasing parts.
To get hotter coolant to your heater core, run the hose to the front of the intake. The factory did this years ago because even though the hose got in the way in the front of the intake, the coolant is much hotter there. This alone will help get your heater core hotter, closer to what the gauge is reading, the gauge reading is taken from the front of the engine. The cooled coolant travels in the water pump from the radiator's lower hose to the engine block, then to the rear of the block and up into the heads and to the front of the heads into the intake to the thermostat to the radiator and around again. So the hottest water is in the front of the intake nearest to the thermostat. This should give you around 50 more degrees hotter coolant in your heater core than from the rear of the intake. GL
Okay I didn’t see some of the last few posts but I was able to flush the heater core today. At first it seemed plugged but then some really murky water came out. It took a while before it was clean. Then I blew out the rest with compressed air. While the system was open I also put in a new 195 thermostat. Got it up to around 160? on the gauge. I also bought myself an infrared thermometer and it is reporting about 180 at the water neck, and 195 at the radiator. The heat inside the car is VASTLY improved. It feels like real heat now. Of course it was also warmer out today-about 55-but I think the issue had been solved. I will test it again on a cold day. Still seems like my gauge is reading low and I’m not sure why. I will have to investigate that further another day. Thanks to all who replied. All the suggestions were very helpful.
The next step you need to do is to check the ground(s) at the sender and the gage as well as the connections on the gage itself. A little loose can cause an errant reading. Is it the correct sender? If you contact Autometer they may be able to give you an OHM rating on that. Was the 170F achieved in the shop? Are the water pump pulleys OEM diameters? Did you try reversing the hoses at the core to actually fill the core from the bottom eliminating and chance of an air pocket? Before anyone else mentions it Puhlease get rid of the plastic fuel filter! ws
