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#1 |
Registered User
Join Date: Mar 2013
Location: Charleston, SC
Posts: 13
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Coolant overflowing from cap
I flushed my coolant system and put a new cap on the radiator recently. Filled the radiator to the top and made sure there were no air bubbles. Started the truck up and brought it to operating temperature and after awhile the coolant started overflowing from the cap and not into the coolant reservoir. There was nothing clogging the line from the radiator to the reservoir and the cap was on there tight. What could be the problem?
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#2 |
Registered User
Join Date: Dec 2007
Location: Santa Maria, Ca.
Posts: 1,423
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Re: Coolant overflowing from cap
Sounds like a faulty cap or the wrong cap for your system
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69 Chevy 4x4 383 Power ![]() |
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#3 |
20' Daredevil (Ret)
![]() Join Date: May 2003
Location: Jefferson State
Posts: 13,628
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Re: Coolant overflowing from cap
^ What he said
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- Mike - 1972 K20 LWB 350/350/205 RIP El Jay |
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#4 |
Registered User
Join Date: Aug 2010
Location: Edwards, CA
Posts: 7,503
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Re: Coolant overflowing from cap
It sounds like two problems. The cap is not sealing and the radiator is overfilled. The spec. is 3" below the bottom of the filler neck cold. Might want to take a look at section 6 of the factory service manual.
If you are running a recovery system you need a cap so designed that will allow the cooling engine vacuum to draw from the tank. The stock cap will only work correctly with a stock dump tube or a returnless catch can.
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Thanks, Tim * VIN/Model Decoders * Power Team Charts (engine/transmission/gear ratio) * Post Your Pickup SPID ** Blazer SPID ** Suburban/Panel SPID * RTFM ... Read The Factory Manuals... download 'em here Highlanders ** Do you have a 1972 Plaid Pickup? ** Plaid Blazer ** Plaid Suburban Last edited by SS Tim; 04-22-2013 at 06:48 PM. Reason: more |
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#5 |
Senior Member
![]() Join Date: Nov 2010
Location: Honolulu Hawaii
Posts: 308
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Re: Coolant overflowing from cap
Fans electric or mechanical? Are they turning on when they are supposed to?
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#6 | |
20' Daredevil (Ret)
![]() Join Date: May 2003
Location: Jefferson State
Posts: 13,628
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Re: Coolant overflowing from cap
Quote:
Agree as to needing the correct cap, as posted above. ![]()
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- Mike - 1972 K20 LWB 350/350/205 RIP El Jay |
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#7 |
Registered User
Join Date: Apr 2013
Location: Knoxville TN
Posts: 1,170
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Re: Coolant overflowing from cap
I fill 3 60's vehicles to the top.
Made sure caps had valving for over flow tank. Installed over flow tanks. I like because conserves coolant and minimizes oxidation. I have noticed radiator sometimes has small air cap when cool but didn't investigate. |
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#8 | |
Registered User
Join Date: Aug 2010
Location: Edwards, CA
Posts: 7,503
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Re: Coolant overflowing from cap
Quote:
A recovery system is plumbed in such a way that the fluid can vacuum return typically a hose extending to the bottom and maintains a minimum fluid level in the recovery tank as well. A catch can only catches it and does not have a return path and may easily be empty. If you have modified the cooling system in such a way as the fluid can return (tank and recovery cap) then yes fill it to the top and enjoy a little more heat rejection. But if there is not a path then use the factory level as intended to reduce the venting from the closed system to the ground or catch can.
__________________
Thanks, Tim * VIN/Model Decoders * Power Team Charts (engine/transmission/gear ratio) * Post Your Pickup SPID ** Blazer SPID ** Suburban/Panel SPID * RTFM ... Read The Factory Manuals... download 'em here Highlanders ** Do you have a 1972 Plaid Pickup? ** Plaid Blazer ** Plaid Suburban |
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Tags |
cap, coolant, radiator, reservoir |
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