Need help- 61 overheating issue
Thread Starter
Instructor
Joined: May 2008
Posts: 109
Likes: 6
From: Weirton West Virginia
Need help- 61 overheating issue
Hello,
I am near completion on a 3 year restoration of 61. I am having some overheating issues. The car has new temp sending unit and thermostat. The temp keeps climbing over 180 with thermostat in but does not overheat with no thermostat in it. It doesn't run hot with no thermostat so can't be water pump issue. I thought maybe I got bad thermostat so tried another and it still runs hot. I have my original sending unit that I may try but was looking for some help on what might be causing car to overheat. Any help would be greatly appreciated.
Thanks.
John
I am near completion on a 3 year restoration of 61. I am having some overheating issues. The car has new temp sending unit and thermostat. The temp keeps climbing over 180 with thermostat in but does not overheat with no thermostat in it. It doesn't run hot with no thermostat so can't be water pump issue. I thought maybe I got bad thermostat so tried another and it still runs hot. I have my original sending unit that I may try but was looking for some help on what might be causing car to overheat. Any help would be greatly appreciated.
Thanks.
John
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I'd suggest buy/borrow a laser temp gun to confirm the temps ($35 at Harbor freight).
I've read that the repro temp senders are very inaccurate.. I'm lucky that the original is still working (and accurate) in my '61.
Is the timing and vacuum advance all set and working?
I've read that the repro temp senders are very inaccurate.. I'm lucky that the original is still working (and accurate) in my '61.
Is the timing and vacuum advance all set and working?
Last edited by SDVette; Jul 7, 2013 at 06:37 PM.
Team Owner
Joined: Aug 2007
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Army
You haven't really said what "hot" is....195 ? 200 ? higher ?
Is it a stock motor ? with the sending unit mounted in the intake manifold ?
Take SDVette's advice and 'shoot' the thermostat housing with a temp gun.
Don't count on a new sending unit being accurate.
Is it a stock motor ? with the sending unit mounted in the intake manifold ?
Take SDVette's advice and 'shoot' the thermostat housing with a temp gun.
Don't count on a new sending unit being accurate.
Thread Starter
Instructor
Joined: May 2008
Posts: 109
Likes: 6
From: Weirton West Virginia
Hello,
The timing and vacuum advance are set on the car. It is the original motor with a fresh rebuild. It was climbing over 200 at about 2000rpms. I still have original sending unit so I can try that one and I will try temp gun as well. Thanks for all the help
John
The timing and vacuum advance are set on the car. It is the original motor with a fresh rebuild. It was climbing over 200 at about 2000rpms. I still have original sending unit so I can try that one and I will try temp gun as well. Thanks for all the help
John
Team Owner
Joined: Aug 2007
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Army
I would definitely try that. That is indeed too warm if the reading is accurate. All a correctly operating thermostat does is provide a slight restriction if its open all the way so I'm not sure what the deal is with the car running cool with it out.
I am assuming the thermostat is installed correctly (pellet side down); don't laugh you wouldn't believe what I've seen over the years!
I am assuming the thermostat is installed correctly (pellet side down); don't laugh you wouldn't believe what I've seen over the years!
Drifting
Joined: Jul 2005
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From: Putnam Valley, New York. Amateur Radio Operator K2NS
Temp
By fresh, do you mean no mileage yet ??? Freshly rebuilt engines will run hotter than normal for a few hundred miles. Put the original sending unit back in--more than likely the one you now have in there is a replacement with the usual problem---reads too high !!! Also, make sure the shroud is there and the fan clutch is operating correctly.
RON
Le Mans Master
Joined: Dec 2007
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From: Puget Sound
The aftermarket sending units are junk and you usually have to try several to find something close. The $30 one I got from Lectric Limited was by far the worst of them all. The $7 Autozone ones are much closer.
The OP needs to make sure his problem is something other than a bad sending unit.
Jim
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Army
I've heard that too...
All I can say is my '61, which I got 300 miles after it was rebuilt never even ran warm (and still doesn't). My souped up Chevelle 396ci engine only had 50 miles on it when I got it - same thing...zero temp issues. Something else going on here IMO.
All I can say is my '61, which I got 300 miles after it was rebuilt never even ran warm (and still doesn't). My souped up Chevelle 396ci engine only had 50 miles on it when I got it - same thing...zero temp issues. Something else going on here IMO.
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John,
Most of the above post are right on.
1.I have my original temp sensor in my 61 used for over 200,000 miles
2.Original radiator, fan, fan shroud, etc.
3.Make sure there is no funky wire from the sensor to the gauge
I have a DART 400 with modern heads that dynoes 500hp mated-up to all the old original 1961 cooling system and never overheats
You say you set the timing and have a stock rebuild engine; however, they are never the same as factory engines 50+ years ago. Not a negative, just not the same cam-valve timing , etc.
Look up and do a LARS timing (as much mechanical advance as you can get without detonation)...factory advance means nothing...just a starting point...optimize YOUR engine timing
It will run better...more torque, more throttle response, and IT WILL RUN COOLER. I do all my buddies old SBC's and they think it is magic.
Joe
Also, I ran without a thermostat for many years; however, after the DART 500hp SBC set-up I need to use a thermostat to keep the temp at 180-200 even in the Houston 95+ temps. It seems to run a bit better at that temp range.
Most of the above post are right on.
1.I have my original temp sensor in my 61 used for over 200,000 miles
2.Original radiator, fan, fan shroud, etc.
3.Make sure there is no funky wire from the sensor to the gauge
I have a DART 400 with modern heads that dynoes 500hp mated-up to all the old original 1961 cooling system and never overheats
You say you set the timing and have a stock rebuild engine; however, they are never the same as factory engines 50+ years ago. Not a negative, just not the same cam-valve timing , etc.
Look up and do a LARS timing (as much mechanical advance as you can get without detonation)...factory advance means nothing...just a starting point...optimize YOUR engine timing
It will run better...more torque, more throttle response, and IT WILL RUN COOLER. I do all my buddies old SBC's and they think it is magic.
Joe
Also, I ran without a thermostat for many years; however, after the DART 500hp SBC set-up I need to use a thermostat to keep the temp at 180-200 even in the Houston 95+ temps. It seems to run a bit better at that temp range.
Last edited by devildog; Jul 7, 2013 at 10:13 PM.