Reproduction Parts for 1916-1964 Chevrolet Passenger Cars & 1918-1987 Chevrolet & GMC Trucks



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#485222 09/09/23 05:03 PM
Joined: Dec 2021
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Grease Monkey
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Grease Monkey
Joined: Dec 2021
Posts: 4
This engine starts easy, runs good BUT overheats (210 deg) within 8 min.
The following is work that has been done:
1 Radiator 'overhauled' but not 'rod-ed out'.
2 water pump rebuilt.
3 With radiator and water pump removed a shop circulating system using an electric pump was installed.
4 Engine cooling system was filled with vinegar (6% acid) the electric pump was run to circulate the solution for about 30 min about every 8 hrs. (to remove years of mineral build-up)
5 Vinegar was flushed and water was used to flush the cooling system. This was done three different times.
6 After the third time the temporary shop system was removed engine cooling system was flushed with a high pressure washer.
7 No change in overheating.

Filling Station - Chevrolet & GMC Reproduction Parts


Filling Station


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ChatMaster - 15,000
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ChatMaster - 15,000
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The most likely suspect is partially plugged radiator. If you have an IR thermometer you can fairly accurately check to see if the entire radiator is getting HOT. You can also use your hand as a temperature tester but be aware to touch lightly at first. The temperature will be the hottest in the path from inlet to outlet. Low or no flow areas will be the coolest. It should be 15-20 deg cooler at the bottom vs. the top as the heat is transferred to the air.

A good radiator shop should be able to flow test the radiator.


How Sweet the roar of a Chevy four!
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Grease Monkey
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Grease Monkey
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Thanks for your reply. I've done the temperature test you recommended two different times with two mercury thermometers and an IR. Also did the touch test. The temps were even across the radiator. I used the IR to measure each cylinder, it seemed the back cylinder heated up the soonest.

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Shade Tree Mechanic
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Shade Tree Mechanic
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Guessing here, but could you have a leaking headgasket? Look for bubbles in the coolant. You can also buy a tester that would detect exhaust gas in the coolant.


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'31 Special Sedan
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Grease Monkey
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Grease Monkey
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I had the head assembly rebuilt then reinstalled with new copper gasket and (fairly new ) bolts. No bubbles.

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Grease Monkey
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Grease Monkey
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I need to know who out there can and is willing to rework my radiator and make the necessary repairs to the bottom tank. 1918 Chev 490 Tudor. Thanks!

Joined: Aug 2017
Posts: 59
Shade Tree Mechanic
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Shade Tree Mechanic
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My 490 did the same thing after a rebuild, it ran a little sluggish and I could hardly go around the block and it was overheating. It was the timing, I had read posts about having the timing wrong could cause overheating, after half dozen try’s I finally got it right.


1917 490, 1928 Depot Hack, 1925 Buick roadster, 1978 Vette pace car, 2002 Z06

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