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Thread: Radiator Core Replacement and Sleeve Thermostat Alternatives

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    Luke Skywalker RAC68's Avatar
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    Radiator Core Replacement and Sleeve Thermostat Alternatives

    Hi All,

    Radiator Core Replacement:
    During a member conversation on improving the cooling of a friend's BJ8 at last nights AHS&T meeting, re-coring of the original radiator was brought up. Many of us have had this done but now finding a facility to upgrade the cooling capacity of an original radiator is becoming more and more difficult. Although my experience and upgrade exposure is to a 4-row Core upgrade, I was informed that there is a Dual Density core replacement that better fits the confines of our original radiator and also increased coolant capacity by close to an additional gallon.

    Can anyone provide experience of this dual density core replacement? What cost range can be expected for the replacement?

    Sleeve Thermostat Alternatives:
    As a proponent of using a Sleeve Thermostat to block the cooling bypass, I was informed that the limited availability of the thermostat has increased the price to a ridiculous level. As an alternative, a Thermostat Bypass Blanking Sleeve (https://mossmotors.com/austin-healey...ypass-blanking) that will close this passage and eliminate as much as 25% of coolant from passing through the radiator. Since most are will not be using their Healeys during cold mid-winter days and can put up with a slightly longer warmup period, is this blanking sleeve a viable alternative? Can this blanking sleeve be combined with a standard thermostat to maintain effective pressure and flow?

    Thanks all,
    Ray(64BJ8P1)

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    Darth Vader John Turney's Avatar
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    Re: Radiator Core Replacement and Sleeve Thermostat Alternatives

    Ray,

    I use the blanking sleeve and a regular thermostat. It works just fine. The blanking sleeve has a couple of 1/8” holes so a monorail amount of coolant can go through the bypass and keep it full.

    I’m interested in the new cores also.
    John, BN4

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    Re: Radiator Core Replacement and Sleeve Thermostat Alternatives

    Hi John,

    Thank you for your response. I have notified my friend to order the blanking sleeve and order one for me as well. As mentioned, I already have a sleeved thermostat in my Healey but, if it fails, paying even the discounted price of $90+++ for a replacement seems ridiculous and will place the blanking sleeve on the shelf … just in case.

    Thanks again,
    Ray(64BJ8P1)

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    Re: Radiator Core Replacement and Sleeve Thermostat Alternatives

    Ray
    i tried the sleeve and normal thermostat in mine but broke the cover doing so. I tried using two green gaskets but it did not keep me from cracking it. So I bought the sleeved thermostat.
    maybe if I had trimmed both green gaskets to fit around the thermostat it might have worked

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    Luke Skywalker RAC68's Avatar
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    Re: Radiator Core Replacement and Sleeve Thermostat Alternatives

    Hi Drone Dog,

    I wonder what is different with John's components and installation that allows him to have a successful installation and what has given you a headache.

    John, is your blanking sleeve from Moss? What brand of thermostat are you using with the sleeve?
    Was there anything you needed to do to install the 2 units

    Drone dog, can you answer the same questions?

    Thanks guys,
    Ray(64BJ8P1)

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    Re: Radiator Core Replacement and Sleeve Thermostat Alternatives

    Gents, when one fits the blanking sleeve and a standard stat the two small flanges sit on top of each other and as a result stand proud of the head . When the stat cover is fitted and tightened down it can leak or crack. The solution is a thicker gasket or to machine a small counter bore to accept the flange height in the stat cover.
    I tried the thicker gasket ( hand cut) then machined the cover in my lathe as a permanent solution.
    I have an alloy head and now only use the stat with no sleeve after having the radiator re-cored with a modern high density copper core . I have the original airflow guides and inner wing shields supplemented with a closure plate between the radiator head tank and shroud, I run a Dennis Welch plastic 5 blade fan. I also use a 10 psi cap and an mgb coolant expansion and recovery tank Engine temp only climbs to 190 when sat in heavy traffic on hot days normal running is 170 to 180.

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    Luke Skywalker RAC68's Avatar
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    Re: Radiator Core Replacement and Sleeve Thermostat Alternatives

    Hi Hassad,

    Thank you for describing the real issue and providing your solution. Withough a lathe or a thicker gasket, is it possible and practical to alter the sleeve to allow proper maiting of the 2 components? Would the sleeve rest properly on other supporting structures if its top flange was shaved, or eliminated entirely, to provide sufficient space for the thermostat to assume standard mounting?

    Also, you mentioned having the radiator re-cored with a high density copper core. Are you referring to a core with an additional row or the Dual Density core I was inquiring about. If the latter is true, can you provide further information (i.e. manufacturer, etc.).

    Thanks again,
    Ray(64BJ8P1)

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    Darth Vader steveg's Avatar
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    Re: Radiator Core Replacement and Sleeve Thermostat Alternatives

    I ran the Moss fail-open thermostat with sleeve for a couple of years with two Moss green gaskets with no problems. The lower gasket needs to have the hole enlarged to accommodate the diameter of the thermostat flange, which now stands proud of the head.

    Machining the cover flange is great if you have your own mill, but otherwise overkill.

    FailOpenWsleeve.jpg
    Last edited by steveg; 06-16-2018 at 01:36 PM.
    Steve Gerow
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    Re: Radiator Core Replacement and Sleeve Thermostat Alternatives

    Steve thats neat, I onlt machined the stat cover because I could. I agree its not necessary if two gaskets or a thicker one works for you go for it.

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    Re: Radiator Core Replacement and Sleeve Thermostat Alternatives

    Correct. Two gaskets, a thick gasket or relief of the housing or head is required.
    John, BN4

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    Re: Radiator Core Replacement and Sleeve Thermostat Alternatives

    I bought the moss sleeve and the moss thermostat. I tried two green gaskets with the inside cut on one of them. But I still did not get the cover, a new one also from moss, down to sit flat. So it cracked as I tightened it. I could have tried again but just went ahead and bought a sleeved thermostat.
    Would like toget those parts I have ready for backup though.

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    Re: Radiator Core Replacement and Sleeve Thermostat Alternatives

    My blanking sleeve (from Moss) did not sit nicely in the engine recess, so I filed and sanded the outer diameter (of the sleeve lip) a little to get it to rest correctly in the head. I also increased the hole diameter in the gasket slightly (with a careful x-acto knife) so that it was around the sleeve and thermostat, rather than on top of them. Seems to work fine.

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    Re: Radiator Core Replacement and Sleeve Thermostat Alternatives

    Maybe if I had not tried to tightened it so tight... I can get heavy handed.

    I also thought about putting just the sleeve in and taking a socket, tapping on the sleeve flange to make sure it is flat in the recess.... might have helped.

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