rad overflow

Old October 15th, 2011, 06:29 PM
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rad overflow

this has happened twice to me now. i have only had the car up to temp twice now. so. everytime that the thermostat opens coolant pours out of the overflow spout on the neck of the rad. Before i had run in up, (it was cold) the coolant was about 3 inches down from the top. any ideas or past experience as to why it would be doing this when the coolant is low even would be great.
thanks Dan
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Old October 15th, 2011, 06:52 PM
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try a higher radiator cap pressure i had the same thing happen to me when i went to a lower temp thermostat it might have a 7lb cap you may need higher. mine had a 7lb cap was fine for the stock 190 temp. stat. but i went down to 165 i had the same issue

Last edited by coppercutlass; October 15th, 2011 at 06:59 PM.
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Old October 15th, 2011, 07:15 PM
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thanks for the tip. its a new cap on a new rad so tomorrow i will go look and see what it is. what lb cap did you end up putting on?
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Old October 15th, 2011, 07:19 PM
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These engines are designed for 15# of pressure.

- Eric
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Old October 15th, 2011, 07:22 PM
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i will check and see tomorrrow what the cap is. if it is the 15 lb, and suggestions as to a cause.
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Old October 15th, 2011, 07:28 PM
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mine had a 7lb cap i know it was probably a band aid for a leak somewhere. but i now have a 16 lb cap but they can go a bit higher i think. It could also be that there may be air pockets in your system run it open with out the cap and if it has bubbles then it has air pockets. let it run up to temp with the cap open then cap it off before you shut it off see if it changes .
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Old October 15th, 2011, 07:31 PM
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i have previousely run it up, with the rad cap off. when the t-stat opened, coolant literally gushed out of the filler so i threw the cap back on.
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Old October 15th, 2011, 08:05 PM
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what about when the over flow is hooked up does it stop at some point filling up . try to let it fill up if it stops after a while it may be air trapped in the system . i never had it happen to me this bad., trapped air becomes hot air pockets and heat rises pushing the coolant upward to relased the trapped air causing the gushing. is the gushing non stop or does it die off .

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Old October 16th, 2011, 02:47 PM
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Do you not have an overflow jug? The best way to get the air out is to use the overflow jug for a few days of running, adding coolant / water to the overflow as it is sucked back up by the radiator...just make sure the hose connected to the radiator is UNDER the fluid level of the overflow jug. As it cools it'll draw fluid back into the radiator.
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Old October 16th, 2011, 11:34 PM
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all helpful. thanks. the coolant is no good at this point and will freeze my block at about 0 degrees celcius. so im going to do a drain and fill and use a vacuum filler to ensure i get all the air out. i think the problem with the rad cap is that it is not sealing on the lower seal yet is bypassing and spitting out the overflow with little to no pressure. seeing as how the previous owner had the car outside for a number of years and the coolant as shitty as it is, i hope no block or head damage occoured. If it appears to be that way.. all i have to say is DAMN'T.
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Old October 17th, 2011, 06:36 AM
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when you fill the coolant take the temp sender out of the manifold and fill it slowly, this will allow the air in the block & heads a place to escape as you fill the radiator. you can easily keep an eye on the coolant passage in the manifold so as to not make a mess and be sure that all the air is out of the engine without making a mess.
radiator caps are cheap, if in doubt try another one, 15lbs minimum...
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Old October 18th, 2011, 10:31 PM
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alright. went and compared a new cap and the lower seal was lower than the original. i purchased it slammed it on and bled the system with new coolant. were good to go. thanks for the input. did these cars come stock with a overflow jug? mine does not have one.
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Old October 18th, 2011, 10:58 PM
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Originally Posted by 4424me
alright. went and compared a new cap and the lower seal was lower than the original. i purchased it slammed it on and bled the system with new coolant. were good to go. thanks for the input. did these cars come stock with a overflow jug? mine does not have one.
I believe they all came with an overflow jug...I'm not 100% positive on that though. Fusick sells a reproduction factory recovery jug but it is EXPENSIVE!!! $199!!! They also sell a reproduction factory washer fluid jug that is CHEAP!!! I bought a washer fluid jug and stuck a hose down through the cap below the fluid line...works like a charm. And it almost looks factory

There are some aftermarket jugs you can try: http://www.yearone.com/serverfiles/f...ain2.asp?cat=3
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Old October 19th, 2011, 12:57 AM
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ouch. i could probably find something more worthy of my 200 bucks! lots of work to go still. getting excited about paint. ill have to get some pics and start a little build thread !
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