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6/13/17 7:34am - Original Message: 'Engine overheating'
Dblancha79 Gold Member
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Weatogue, CT - USA

Vette(s):
1979 C3 L82 350 cu in

Joined: 6/29/2015
Posts: 22
I have a 79' L82 350 engine and I can't keep it from over heating. I installed an aluminum radiator new hoses and thermostat. The electric fan temperature switch is new and fan rotates when connected to 12 volt battery.
After running the car for about 20 minutes if I stop and idle for 5-8 minutes the temp climes to 240F. If I turn the heater on it drops back to normal around 200F so that little extra heater core cooling seems to solve the issue.
.
Any help would be appreciated on what to try next.


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"Made to be run hard"
Simsbury, Ct.
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6/13/17 8:13am - Reply: 'Re: Engine overheating'
manchestershark Lifetime Member
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Equinunk, PA - USA

Vette(s):
1972 conv, 4-speed, 350, 200hp, numbers match, rally wheels, war bonnett yellow w/white top. good condition, nice driver.

Joined: 10/31/2007
Posts: 1895
How bout the thermostat being installed up side down. The little pointed dome has to face up/out. Is the fan blowing the correct way? Is it in front of the radiator or behind it?

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6/13/17 2:00pm - Reply: 'Re: Engine overheating'
gtr1999
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Wallingford, CT - USA

Vette(s):
1969 350 4 spd drop top 1972 350 auto coupe

Joined: 5/2/2016
Posts: 53
Can you confirm using a heat gun the fan comes on when it should? Did you use a DeWitt setup?
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6/13/17 2:28pm - Reply: 'Re: Engine overheating'
Dblancha79 Gold Member
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Weatogue, CT - USA

Vette(s):
1979 C3 L82 350 cu in

Joined: 6/29/2015
Posts: 22
I will double check thermostat direction.  My fan set up is  Radiator then electric fan then the engine fan. Both fans should be pulling air through the radiator.
Thanks


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"Made to be run hard"
Simsbury, Ct.
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6/13/17 2:32pm - Reply: 'Re: Engine overheating'
Dblancha79 Gold Member
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Weatogue, CT - USA

Vette(s):
1979 C3 L82 350 cu in

Joined: 6/29/2015
Posts: 22
Yes I  can confirm with a heat gun but I am sure it is overheating. It will idle rough and stall if I push the gas too hard. almost vapor locks.  I don't know what a Dewitt system is but I will look it up.

Thanks


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"Made to be run hard"
Simsbury, Ct.
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6/13/17 5:38pm - Reply: 'Re: Engine overheating'
gtr1999
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Wallingford, CT - USA

Vette(s):
1969 350 4 spd drop top 1972 350 auto coupe

Joined: 5/2/2016
Posts: 53
DeWitts is a radiator mfg and one of the best out there.
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6/13/17 6:51pm - Reply: 'Re: Engine overheating'
stingrayjim jr Lifetime Member
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SHELBYVILLE, TN - USA

Vette(s):
1976 L48 auto

1978 L82 4speed

1994 LT1 6speed

Joined: 7/5/2002
Posts: 3934
If i picture this right, you have both fans on the engine side?..... so the clutch fan(the fan connected to the water pump) is right behind the electric fan...right???   first, i think i would place the electric in front of the radiator if you are going to use both fans, second, make sure the electric fan is blowing the correct way, in this case,  pulling air through and not blowing toward the front of the car......hook the fan up bypassing the temp switch and get a tissue or something of the like and verify the direction that the fan is blowing....
if you can put the fan in front, be sure to also put the fan shroud(if you have it) back on for the clutch fan,  as it does help
good place to start....


|UPDATED|6/13/2017 3:51:28 PM (AZT)|/UPDATED|


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StingrayJim
NCM Lifetime Member #1936

Stingray's '76                             StingrayJr's '78                           Lil Red '94

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6/13/17 7:11pm - Reply: 'Re: Engine overheating'
manchestershark Lifetime Member
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Equinunk, PA - USA

Vette(s):
1972 conv, 4-speed, 350, 200hp, numbers match, rally wheels, war bonnett yellow w/white top. good condition, nice driver.

Joined: 10/31/2007
Posts: 1895
You could also by pass the temperature switch and wire it hot to a manual switch. That way you could turn it on and off at your leisure. It also assures you it's on and running.

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6/13/17 11:05pm - Reply: 'Re: Engine overheating'
73shark
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Overland Park, KS - USA

Vette(s):
1973 Orange Metallic Coupe (orig owner), L82, 4 spd (WR), PS, (A/C & PW (I installed from wrecked 73)), leather, AM/FM Stereo, ran with '65 FI unit earlier & will again some day.

Joined: 7/9/2003
Posts: 376
Is the area between the A/C condenser and radiator clean? 

Are all of the seals around the radiator intact and in place? 

Is the air dam under the front end there? 

Might check the t-stat in boiling water to see if it opens all the way.  Saw a statistic once where about 20% of new ones are bad.

Is the spring in the lower radiator hose that keeps it from collapsing?

Assumptions I made are that the electric fan and engine-driven fan are operational.

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1973 L-82 4 spd

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6/14/17 5:05pm - Reply: 'Re: Engine overheating'
Toplander
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Athens, IL - USA

Vette(s):
1975 coup 4speed leather interior. Silver with oxblood interior

Joined: 7/13/2016
Posts: 3
I have the same problem with my 75. I have a new Champion 3 core radiator with dual electric fans and fan shroud. I have removed the factory fan and clutch, changed thermostats from 195 to 180 and now back to 195 with a single 1/8" hole drilled in it. The fans come on at 180 degrees and are blowing the correct direction (pulling air through the radiator and blowing out towards the engine). When replacing the radiator i also replaced the core support, all the radiator seals and the air dam  underneath. My temp gauge reads 230 degrees which I have verified with a heat gun. So far I have tried everything i can come up with on forums except replacing the lower radiator hose, mine does not have a spring in it, but by watching it it does not collapse and both hoses are hard from internal pressure. Any Ideas?   

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6/14/17 5:14pm - Reply: 'Re: Engine overheating'
gtr1999
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Wallingford, CT - USA

Vette(s):
1969 350 4 spd drop top 1972 350 auto coupe

Joined: 5/2/2016
Posts: 53
check timing and carb for being too lean.
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6/14/17 5:44pm - Reply: 'Re: Engine overheating'
Toplander
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Athens, IL - USA

Vette(s):
1975 coup 4speed leather interior. Silver with oxblood interior

Joined: 7/13/2016
Posts: 3
I did notice today that my glass fuel filter at the carb is never full and fuel flow only seams to be a small squirt every so often. I have already ordered a new fuel pump as mine does look to possibly be original. I will also borrow a timing light to see what the timing is set at. The engine has always run very good. thanks for the help, I will let you know what i find.  

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6/14/17 9:12pm - Reply: 'Re: Engine overheating'
Tomtall
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Vette(s):
1973 Coupe -- 454 / 4 speed - Black on Black, Greenwood aftermarket turbo hood, Greenwood GTO style front bumper.American Racing Vector rims.

Joined: 3/5/2016
Posts: 43
Fan shroud in place ? Ignition Timing correct ? Collapsed radiator hose ? Slipping water pump belt ?

|UPDATED|6/14/2017 6:12:32 PM (AZT)|/UPDATED|
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6/15/17 3:17am - Reply: 'Re: Engine overheating'
stingrayjim jr Lifetime Member
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SHELBYVILLE, TN - USA

Vette(s):
1976 L48 auto

1978 L82 4speed

1994 LT1 6speed

Joined: 7/5/2002
Posts: 3934
Toplander.  You might have an air bubble in the system....try running it with the cap on loose and see if there is a difference.... and besides the lower radiator hose, you might have a water pump issue.??  Hopefully it isn't a  head gasket....

And the fuel filter, mine does that too, i have one of the glass type filters with the replaceable filter. Using an electric holley blue pump it doesn't fill up either, but it gets fuel, so, all that really matters :)
 


|UPDATED|6/15/2017 12:17:30 AM (AZT)|/UPDATED|


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StingrayJim
NCM Lifetime Member #1936

Stingray's '76                             StingrayJr's '78                           Lil Red '94

(click each one to see a bigger version)
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6/15/17 8:42pm - Reply: 'Re: Engine overheating'
gtr1999
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Wallingford, CT - USA

Vette(s):
1969 350 4 spd drop top 1972 350 auto coupe

Joined: 5/2/2016
Posts: 53
Hi Guys
Just one thing, please get rid of those glass inline filters those are very risky, if they break you have a fire.
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6/15/17 8:50pm - Reply: 'Re: Engine overheating'
Dblancha79 Gold Member
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Weatogue, CT - USA

Vette(s):
1979 C3 L82 350 cu in

Joined: 6/29/2015
Posts: 22
Thanks all for ideas. I think I found the issue. The air dam was flopping so I wired it open awhile ago to get max air in the engine compartment that gets so hot. When the car idles I think the engine fan pulls air from the open air dam vs through the radiator.  Also when I installed the aluminum radiator the fan shroud doesn't fit tight to the radiator. I'm in the process of buying rubber seals to add to the shroud.  I also don't think the new temperature switch I bought some time ago works right. I put it in boiling water but can't get an ohm reading through it.  I may just wire the electric fan to a switch as suggested as I know the electric fan works if you get 12 volts to it.

Thanks everyone.


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"Made to be run hard"
Simsbury, Ct.
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6/18/17 9:48pm - Reply: 'Re: Engine overheating'
Toplander
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Athens, IL - USA

Vette(s):
1975 coup 4speed leather interior. Silver with oxblood interior

Joined: 7/13/2016
Posts: 3
My car was definitely running lean because of a weak fuel pump. after replacing the fuel pump the filter remains full and performance is much better, as far as temp goes todays test drive it ran 205 degrees, although the air temp was only 80 compared to 95 when it was running 230 plus. I will still check timing and try with rad cap loose to see what happens. thanks again for all the help.    

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