how warm is running too warm?

DartConvertible · 03-14-2008, 11:18 AM

I have a '68 Dart GT with a 318. The PO put on a Holley aluminum intake manifold and an Holley 4bbl. The car runs kind of warm, with the gauge swinging from just below the hot marker to on the hot marker. The engine doesn't seem hot, the coolant isn't when I open up the radiator. I'm wondering if there the gauge sender is reading differently, screwed into an aluminum manifold and not the stander iron one. Any thoughts are great,
thanks

Peter

440roadrunner · 03-14-2008, 01:18 PM

First thing I'd suspect is that the gauge reading is wrong.
These cars are getting old, and anything can happen
There's an "instrument panel regulator" up behind the panel that feeds the temp, oil, gas gauges reduced voltage. These can go bad.
The gauge itself could be innaccurate.
Are you sure that the sender is the correct one? Even if correct, it could be bad.
Try and find something to measure temp, if nothing else, find a cheap HVAC or meat thermometer and tape it to the side of the top hose. Wrap a rag or two around it to insulate it
The difference in the manifold should not make a difference.

DartConvertible · 03-14-2008, 02:17 PM

Thanks, I'll try the thermometer. What should it read? I wondered if it might be the thermostat, but wouldn't that make the radiator gush when opened, and the car running? I wondered about the gauge and sender, but thought that if the temp was rising quickly, like after climbing a grade on I-5 to Grant's Pass, that something might be wrong. For what it's worth, there was no substantial change in the temperature coming out of the heater, on high.

440roadrunner · 03-14-2008, 03:53 PM

If it's overheating, the radiator should be building lots of pressure, unless you have a bad cap or leak somewhere

Are you saying the heater does NOT put out heat? That's a bad sign. Is there any chance you have an "air lock" in the cooling system? Both heater hoses should be warm, and when the stat opens and the engine warms up, you should see circulation in the radiator. Top hose should be warm/ hot, bottom almost as warm. You might not be able to tell the difference.

DartConvertible · 03-14-2008, 05:13 PM

no no, the heater works fine. When the radiator cap is open, the engine warmed up and on, it just flows like it should. I felt the radiator, the hose and the thermo housing, and nothing felt too hot- I could just about hold my hand on it. Everything works fine, except for the gauge. There seems to be a lot of questionable work, not irrepairable, that was done to the car, and I thought the could've messed up the sender when they changed the manifold, or put in the wrong thermostat. I wondered too if the car was getting too hot, if I'd feel it in the hoses and radiator. Sounds like I would....

thanks a ton

Peter

440roadrunner · 03-14-2008, 07:10 PM

OK, so we've determined that it apparrently NOT oveheating, and the heater works.

I would first replace the temp gauge sender and see what happens.

DartConvertible · 03-17-2008, 05:22 PM

right, gonna get a new sender. Thanks

Peter

03-14-2008, 11:18 AM	#1 (permalink)
DartConvertible Junior Member Join Date: Mar 2008 Location: on the coast in Sonoma County Posts: 15	how warm is running too warm? I have a '68 Dart GT with a 318. The PO put on a Holley aluminum intake manifold and an Holley 4bbl. The car runs kind of warm, with the gauge swinging from just below the hot marker to on the hot marker. The engine doesn't seem hot, the coolant isn't when I open up the radiator. I'm wondering if there the gauge sender is reading differently, screwed into an aluminum manifold and not the stander iron one. Any thoughts are great, thanks Peter

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03-14-2008, 01:18 PM	#2 (permalink)
440roadrunner Senior Member Join Date: Nov 2007 Posts: 272	First thing I'd suspect is that the gauge reading is wrong. These cars are getting old, and anything can happen There's an "instrument panel regulator" up behind the panel that feeds the temp, oil, gas gauges reduced voltage. These can go bad. The gauge itself could be innaccurate. Are you sure that the sender is the correct one? Even if correct, it could be bad. Try and find something to measure temp, if nothing else, find a cheap HVAC or meat thermometer and tape it to the side of the top hose. Wrap a rag or two around it to insulate it The difference in the manifold should not make a difference.

03-14-2008, 02:17 PM	#3 (permalink)
DartConvertible Junior Member Join Date: Mar 2008 Location: on the coast in Sonoma County Posts: 15	Thanks, I'll try the thermometer. What should it read? I wondered if it might be the thermostat, but wouldn't that make the radiator gush when opened, and the car running? I wondered about the gauge and sender, but thought that if the temp was rising quickly, like after climbing a grade on I-5 to Grant's Pass, that something might be wrong. For what it's worth, there was no substantial change in the temperature coming out of the heater, on high.

03-14-2008, 03:53 PM	#4 (permalink)
440roadrunner Senior Member Join Date: Nov 2007 Posts: 272	If it's overheating, the radiator should be building lots of pressure, unless you have a bad cap or leak somewhere Are you saying the heater does NOT put out heat? That's a bad sign. Is there any chance you have an "air lock" in the cooling system? Both heater hoses should be warm, and when the stat opens and the engine warms up, you should see circulation in the radiator. Top hose should be warm/ hot, bottom almost as warm. You might not be able to tell the difference.

03-14-2008, 05:13 PM	#5 (permalink)
DartConvertible Junior Member Join Date: Mar 2008 Location: on the coast in Sonoma County Posts: 15	no no, the heater works fine. When the radiator cap is open, the engine warmed up and on, it just flows like it should. I felt the radiator, the hose and the thermo housing, and nothing felt too hot- I could just about hold my hand on it. Everything works fine, except for the gauge. There seems to be a lot of questionable work, not irrepairable, that was done to the car, and I thought the could've messed up the sender when they changed the manifold, or put in the wrong thermostat. I wondered too if the car was getting too hot, if I'd feel it in the hoses and radiator. Sounds like I would.... thanks a ton Peter

03-14-2008, 07:10 PM	#6 (permalink)
440roadrunner Senior Member Join Date: Nov 2007 Posts: 272	OK, so we've determined that it apparrently NOT oveheating, and the heater works. I would first replace the temp gauge sender and see what happens.

03-17-2008, 05:22 PM	#7 (permalink)
DartConvertible Junior Member Join Date: Mar 2008 Location: on the coast in Sonoma County Posts: 15	right, gonna get a new sender. Thanks Peter