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Radiator Cap Part Number

Discussion in 'Engine & Performance' started by LoneWolf3574, Oct 12, 2019 at 8:51 PM.

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  1. LoneWolf3574

    LoneWolf3574 Senior Member Military

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    Alrighty then, I've been through the parts manual and can't seem to locate a part number for the radiator cap. All I'm finding is 050866226AA CAP, Coolant Reserve Tank, which I noticed is the same part number a couple of pages later for the reservoir cap, the exact same description even. I know that a flimsy piece of yellow plastic won't hold pressure. So, does anybody have the proper part number for a good old Ma Mopar OE radiator cap for the 2006 Rams?

    I’ve got a Stant on right now, but it seems to not be letting the coolant be drawn back into the radiator. I’d rather avoid aftermarket parts; I have had a rotten streak with them failing in the last few years if they’re not OE.
     
  2. joshuaedmister

    joshuaedmister Member

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    I'm no expert but last I checked radiator caps are relatively universal, find one the right psi and hole size from your local parts store, kinda like a gas cap, as long as it fits it should work but the psi ranges for different applications, but it should say either stamped into the cap or on a sticker what it's rated for stock, 5 psi is usually what I go with though but some vehicles are designed different

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  3. joshuaedmister

    joshuaedmister Member

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    But if you're talking your reservoir tank it doesn't take much for that to keep pressure because the lid on that doesn't necessarily hold say 15 psi, it has to go through a few things and they usually have some type of breather built in anyways otherwise it would burst first time it heats up and expands the antifreeze if there were no breather to release pressure

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  4. LoneWolf3574

    LoneWolf3574 Senior Member Military

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    You are pretty much correct, the only thing that really varies on a radiator cap from Stant or one from ACDelco is quality. As I stated, I've had rotten luck with the aftermarket in the last few years and would rather buy an OE radiator cap. Without going to the stealership to buy it, of course.

    The reservoir isn't pressurized, it is just an overflow tank to store the excess coolant before it is drawn back into the radiator when the engine cools down and is always at atmospheric pressure. You might be thinking of a pressure tank like what is on my wife's 2015 Ford Escape. The radiator cap for the Ram can hold up to 16psi before it releases the excess pressure and coolant to the reservoir. I personally have no idea why you would want a 5psi radiator cap as that would change your boilover temperature to about 227F which is dangerously low on an engine with a 203F thermostat. A 16psi cap makes that boilover temperature around 260F which is much safer.

    EDIT - A general rule of thumb is ~3F for every 1psi of the radiator cap. More is NOT always better.
     
  5. joshuaedmister

    joshuaedmister Member

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    Good to know that, I knew Chevy was pressure tank but couldn't remember on my ram

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  6. HemiLonestar

    HemiLonestar Senior Member Military

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    Need to actually run the part number before you pass judgement: https://www.rockauto.com/en/partsearch/?partnum=5086226AA
    It is the correct part number for a metal rad cap. I saw what you were talking about in the parts manual, I've noticed many typos like that in these things over the years.
     
  7. LoneWolf3574

    LoneWolf3574 Senior Member Military

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    I apolgize for the long wait on replying, life happens. I went over to my parent's house the other day and my dad suggested we test my cap. It did a couple of intersting things such as not pressurizing initially and then only pressurizing to ~12psi, both of which confirm my suspicion of a failed cap. Since this is my 2nd cap in a year from a brand (Stant) that I've trusted for a couple of decades, I'm going to jump ship and go with a Gates. I feel that Stant has gone the way of Fram and just isn't worth my time anymore. Thank you all for your assistance in trying to find the actual OE part number, but I'll just have to settle for an aftermarket for now.
     
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  8. HemiLonestar

    HemiLonestar Senior Member Military

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    As long as it works, that's all that matters :waytogo:
     
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