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Thread: Roadster Rebuild Diary from Cornwall

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  1. #241 Re: Roadster Rebuild Diary from Cornwall 
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    Thanks Hugh and Dave,
    Hugh you are more than welcome to pop around, I will also try to pop out to see you.
    I spent another hour or so flattening back the bonnet and out with the polisher. I was recommended Menzerna cutting compound so bought the 3 stage pack. Not used the ultra fine though. I am learning as I go and results below, happy with that.

    6E18A211-721D-4832-B7B8-0813BE2EDF64.jpeg

    6CB3D060-C075-4224-B468-45DB569B32AF.jpeg
    1275 Marina/Ital based LWB Roadster in the process of a ground up rebuild.
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  2. #242 Re: Roadster Rebuild Diary from Cornwall 
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    I’m not a big fan of two fans. The engine is designed to run at an optimum temperature. Most wear occurs during the warm up. In general use the forward movement of the car should be more than enough to cool the radiator. Marlins have well vented engine compartments. Essentially even very slow speeds should be enough to ensure the air touching the radiator is at ambient temperature. Even a 10-20mph breeze will keep things cool. The fan should only be needed to draw air through the radiator in stationary air. If you are having problems with cooling it is almost certainly fuel mixture or timing issues. The most common being a lean mixture.

    IMHO the thermostatically operated electric fan would be best, ideally fitted to the rear of the radiator to shield from ill-fated insects. It also makes routine cleaning of the radiator easier. I originally fitted Millie’s fan in front of the radiator. So I have done the experiment and can confirm the result. The electric fan will not operate during the warm up period. The engine mounted fan will slow engine warm up and waste energy in normal operation.

    Sorry to mention the fan again but to me it looks like a glaring slip-up on an otherwise outstanding rebuild.
    Paul

    PS: I expect to gain no fans from my first sentence.
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  3. #243 Re: Roadster Rebuild Diary from Cornwall 
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    Thanks for your input Paul,
    It turns out that I am just using the thermostic fan. I purchased the inline thermostatic switch that Hugh recommended and when plumbing in the classic Mini rad it became obvious that the engine fan would spin too close to the pipes so I have removed it.
    Cheers, Martin.
    1275 Marina/Ital based LWB Roadster in the process of a ground up rebuild.
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  4. #244 Re: Roadster Rebuild Diary from Cornwall 
    frequent forum contributor Club Member boustrophedon's Avatar
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    Whilst I would agree with the comments about using an electric fan, I think the statement that the engine bay is "well ventilated" to be wrong.

    Air can potentially get into the engine bay OK, but is stalled on the way out by the high pressure air trapped by the wings and forced under the car as it moves. The wings force air up into the engine bay creating high pressure behind the radiator. The only way out for the cooling air is through the tiny area of the bonnet louvres and back under the car against the air trapped by the wings. A blast of hot air comes up through the handbrake slot in mine. This I believe is the real reason for the poor cooling found in many Roadsters.

    The engine driven fan does very little as it is unducted and too far from the radiator to do any good at all.
    Formally DonSayers on here.
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  5. #245 Re: Roadster Rebuild Diary from Cornwall 
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    Quote Originally Posted by boustrophedon View Post
    Whilst I would agree with the comments about using an electric fan, I think the statement that the engine bay is "well ventilated" to be wrong.

    Air can potentially get into the engine bay OK, but is stalled on the way out by the high pressure air trapped by the wings and forced under the car as it moves. The wings force air up into the engine bay creating high pressure behind the radiator. The only way out for the cooling air is through the tiny area of the bonnet louvres and back under the car against the air trapped by the wings. A blast of hot air comes up through the handbrake slot in mine. This I believe is the real reason for the poor cooling found in many Roadsters.

    The engine driven fan does very little as it is unducted and too far from the radiator to do any good at all.
    I agree the aerodynamics of the Marlin leave a lot to be desired. Quite few members add vents to the top of the bonnet to improve flow through the engine compartment. When on the motorway home from one car show I discovered that the engine compartment is indeed at a higher pressure than the surrounding air when the bonnet popped up. Some clown must have inspected my engine compartment and not replaced the bonnet catches.

    I have read that engineers spend more time getting airflow through the engine compartment than around the bodywork of production cars. Anyone interested in F1 will also recognise the importance of cooling airflow. I don’t suppose anyone has access to a wind tunnel it would be interesting to see the actual airflow over a marlin.

    The fact remains that most Marlins, even those with V8s, are able to tow trailers and caravans uphill without overheating.

    Perhaps “adequately ventilated” would have been more appropriate.
    Paul
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  6. #246 Re: Roadster Rebuild Diary from Cornwall 
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    Quote Originally Posted by milliemarlin View Post
    The fact remains that most Marlins, even those with V8s, are able to tow trailers and caravans uphill without overheating.
    Paul
    Except that numerous forum entries and Pitstop articles tell a long history of overheating. Recognised by Paul Moorehouse as well!
    MOC member since 05/97
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    The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.

    Loads of Marlin Reference can be found documents here or there.
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  7. #247 Re: Roadster Rebuild Diary from Cornwall 
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    Quote Originally Posted by stevejgreen View Post
    Except that numerous forum entries and Pitstop articles tell a long history of overheating. Recognised by Paul Moorehouse as well!
    Perhaps “mostly adequately ventilated” would have been more appropriate.
    Paul
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  8. #248 Re: Roadster Rebuild Diary from Cornwall 
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    I wonder how all the 7’s cope with cooling.
    On another note my seats turned up today, yay.

    31CB7DF3-E7FB-4D56-997B-1798B2D94B36.jpeg
    1275 Marina/Ital based LWB Roadster in the process of a ground up rebuild.
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  9. #249 Re: Roadster Rebuild Diary from Cornwall 
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    Pretty, pretty

    Adrian
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  10. #250 Re: Roadster Rebuild Diary from Cornwall 
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    Fairly old and will need trimming sometime in the future but they are comfy.
    1275 Marina/Ital based LWB Roadster in the process of a ground up rebuild.
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