Overheating

calves1299 · Post subject: Overheating (Thu Mar 08, 2012 11:55 am)

I have a 66 dart with a 1982 engine in it. I have replaced radiator, fan, upper, lower hose, water pump, stat, and temp sensor.
It only gets hot when I'm driving down the road. When I stop it cools right back down to where it should be.
So today I jack up my front end as high as I can get it, pull the stat out and run the car. It barely picks up off the cool side, I let it run for 1/2 an hour. Nothing. I let it cool and put the stat back in (with a hole drilled in it) and let it run for about 45 minutes. It never gets quite to 1/2 way, I think I'm good. drop it bag down and it's doing great. Drive it out and before I can even get out of my subdivision the temp gauge is almost pegged.
I pull into a parking lot and sit there stopped it goes back to normal. I let my foot off the brake and with it rolling at idle the needle starts to move towards hot! I have to get this car cooled down as it is my DD right now. I drive about 12 miles back and forth to work about 12 miles each way. The morning won't be so bad because i leave at 6 am, but driving back at 5 is gonna make me freak out.
Any ideas on this?

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66 dart 225

hantayo13 · Turbo EFI Joined: 19 Feb 2005 Posts: 1735

how in coolant flow???? did you check thermostat ????fully open at 195(water and meat thermometer) timing????? bad sendor ???? is it boiling over...or just readin hot

calves1299 · Post subject: (Thu Mar 08, 2012 1:53 pm)

coolant cruises through when the stat is not in. the stat is a 160 degree. I checked to make sure it opened correctly. I just replaced the Sensor. It is not boiling over at all, doesn't smell or run funny at all. when i pull the cap off the radiator it easy, no pressure at all.

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66 dart 225

hantayo13 · Turbo EFI Joined: 19 Feb 2005 Posts: 1735

you want a 195 in a slant...

calves1299 · Post subject: (Thu Mar 08, 2012 3:42 pm)

It does the same thing when the stat is out.

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66 dart 225

calves1299 · Post subject: (Thu Mar 08, 2012 4:59 pm)

Put the 195 stat in. Engine warmed up, and it seemed to change out coolant but very slowly. Idling in my driveway its running pretty hot. The top radiator hose feels like I can squeeze it together pretty easily. So I know it's not filled with liquid. I have the car up on blocks trying to bleed out any bubbles now. I'm scared cause I gotta drive this tthing in the am. I am trying to bleed it with the cap off and the heat cranked

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66 dart 225

Doc · Post subject: (Thu Mar 08, 2012 5:12 pm)

There could be a short on the "sender side" of the temp gauge curcuit.
A good "cross-check" is to install a mechanical temp gauge to see if there is really an overheating problem or if it is a gauge issue.

See This Link for a handy mechanical temp gauge that will screw right into your current sending unit location.
DD

calves1299 · Post subject: (Thu Mar 08, 2012 5:22 pm)

Took it down the street and she pegged right away. Pulled back into the driveway and she went right back to running cooler. What am I doing wrong? If it was the head gasket, wouldn't it just stay pegged? WOuld the gauge in the dash be broken?

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66 dart 225

calves1299 · Post subject: (Thu Mar 08, 2012 5:24 pm)

Thanks Doc, I'm on it.

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66 dart 225

slantvaliant · Post subject: (Fri Mar 09, 2012 8:27 am)

I wonder if your lower hose is collapsing at normal engine speeds, blocking coolant flow.

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Slanted Opinion · Turbo EFI Joined: 22 Feb 2005 Posts: 1087 Location: Maine

Agreed with SlantValiant. Is there a spring in your lower hose? There should be.

SlantSixDan · Post subject: (Fri Mar 09, 2012 11:00 am)

If the lower hose is collapsing, it means the radiator is clogged. It does not mean there's a spring missing from the hose. Putting a spring in the hose might address the symptom for awhile, but will not address the problem. The OP states the radiator has been replaced, so that's probably not the problem, but if there was a lot of trash in the engine that wasn't cleaned out before the new rad was installed, it could have clogged quickly. It bears draining the rad far enough to look at the tops of the tubes. If there's visible trash, the problem has probably been found.

If the radiator is clean, then another thing to check is whether the fan was installed right way round. If it was installed backwards, it will be trying to push air forward through the radiator. That will work as long as the car is standing still, but not when the car is moving, because the car's forward motion will be trying to push air rearward through the radiator.

Neither 160° nor 195° is the correct thermostat for a 1966 model, no matter what year engine is installed. The correct thermostat is 180°.

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coconuteater64 · Post subject: (Fri Mar 09, 2012 2:00 pm)

Not to hijack a thread, but what is considered normal operating range for a slant? If he hooks up a mechanical thermostat, those numbers won't mean anything unless he knows.

Dan, good idea about the fan.

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Fopar · Post subject: (Fri Mar 09, 2012 4:06 pm)

Not to be argumentive, but putting the fan on backwards will only cause cavitation or noise. Take a good look at the fan, to push air into not pulling air through radiator the pitch must be reversed!

Richard

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1974duster kev · Post subject: (Fri Mar 09, 2012 4:16 pm)

Sounds like the gauge is the issue.
He never said it boils over or showed any signs of overheating, besides the gauge reading crazy.

Kev

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