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Thread: reason for it said 1500 has cooling (run to hot) problems?

Discuss the Austin Healey Sprite and the MG Midget. Two different but similar cars sometimes referred to collectively as the Spridget.

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    Question reason for it said 1500 has cooling (run to hot) problems?

    Concerning the 1500 MG Midget, I hear talk that it hascooling problems (runs to hot) and people recommend using an oil cooler (to cool the oil and hold a better oil pressure). In connection with this I have seen it saidthat the design is poor which causes this issue of running hot.
    I have never seen anyone say WHY the 1500 has coolingproblems. Does anyone have a good engineering/mechanical explanation ofwhy the 1500 has cooling problems?
    My only thought is that ones with cooling problems havean old radiator that doesn't eject heat well (as opposed to a new/cleanradiator) and/or have tuning problems with timing and/or carb which isproducing to much heat at combustion.
    Any thoughts or solid explanation on this?

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    Great Pumpkin JPSmit's Avatar
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    Re: reason for it said 1500 has cooling (run to hot) problems?

    I have never heard of or experienced issues with the 1500 running hot. Mind you, I did exactly what you mention - block boiled, rad rebuilt, new hoses. It runs solidly and always in a good temperature range. That said, what 1500's do tend to have issues with vapour lock. The design issue that it did have, was that the catalytic converter can was located right under the carburetor. This combined with the fact that the carb heat shield tended to deteriorate/ disappear over time and the reality that the gas of today is not what it used to be has caused the aforementioned vapour lock issues.

    Now, all that being said, I am also of the opinion that vapour lock way over diagnosed. I regularly read about vapour lock issues when it is fuel filter, or mixture, or fuel pump, or dirty tank or ..... I don't believe it is a common (especially in 1500's) as people think.
    John-Peter Smit
    1976 MG Midget
    1969 Vauxhall Viva GT
    1958 Fiat Multipla (Barn art)

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    Re: reason for it said 1500 has cooling (run to hot) problems?

    Mine has never run hot. They say the Midget 1500 runs hot because of a smaller engine compartment and radiator compared to the Spitfire it came from. I have a cooler that came with a parts car that i haven't put it on yet. I don't know if I will.

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    Re: reason for it said 1500 has cooling (run to hot) problems?

    I raced my Spridget with a 1500 for over 7 years. No problems overheating and never ran an oil cooler. Be sure block is flushed with clean 50/50 water-anti-freeze (too much anti-freeze can cause overheating). Be sure there is no air locks in cooling system; "burp" system by squeezing lower rad hose with cap off. Use a good thermostat (I like a 165F but a 180F is good too). If lower hose is old, check and/or replace. This hose is under suction and if it becomes soft with age, it will suck closed when engine is running at highway speeds.

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    Re: reason for it said 1500 has cooling (run to hot) problems?

    Along the same line that the 1500 runs hot, why is it said that an oil cooler is needed for the 1500 because of the poor cooling design to deal with hot oil and low oil pressure?

    I ask some of this since at startup i get 70 psi cold, 30-40 psi idle hot, 50-60 psi hot at 3000 rpm cruising down the road. At times though i get 15-20 psi hot idle especially on a hard drive.

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    Re: reason for it said 1500 has cooling (run to hot) problems?

    My 1098 in Bugsy my '68 I just sold had the same issue. I attributed the rise in water temps to a weak lower radiator hose partially collapsing under high sustained RPM's. Oil pressure would drop from 70 to 55 lb as temps rose. A cool down coming off of the Expressway ramp would drop temps back to below N and oil pressure back up to 60-65 lbs. The fact that temps and pressures would change that quickly I attributed to partial copllapse of the hose. My thought was to put a copper elbow in there to make sure hose did not collapse under high suction. It's a very short hose but goes through a lot of gyrations to get connected from the radiator to the lower pipe.
    Jim Gruber - Apollo Beach, FL
    Bugsy I - '68 Sprite w BE Bonnet - Gone but not forgotten
    Bugsy IV - '60 Bugeye - 1,275+.040 and a 5-Speed - CA Car - 2nd Owner from new - 10/12 Painting done, reassembly, cutting, and buffing in progress.

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    Re: reason for it said 1500 has cooling (run to hot) problems?

    Makes sense to me. I fully understand that as temps rise oil becomes thinner and oil pressure will drop.
    My engine was rebuilt 2 years ago and don't think it is worn parts. I also have checked play in the crabk shaft to check for the thrust washer wear. I also have replaced radiator and hoses. In rhe rebuid i did go to a 9:1 compression pistons and head. With the higher compression producing more hp, maybe that is producing more heat.

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    Re: reason for it said 1500 has cooling (run to hot) problems?

    Timing settings have a lot to do with heat production and cooling. Too far advanced = heat if I recall correctly. Retarding a gegree or two may improve cooling. Someone else I know will chime in here if I'm incorrect.
    Jim Gruber - Apollo Beach, FL
    Bugsy I - '68 Sprite w BE Bonnet - Gone but not forgotten
    Bugsy IV - '60 Bugeye - 1,275+.040 and a 5-Speed - CA Car - 2nd Owner from new - 10/12 Painting done, reassembly, cutting, and buffing in progress.

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    Re: reason for it said 1500 has cooling (run to hot) problems?

    1976 1500 engine 9:1 compression
    Timing set at 10 BTDC

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    Great Pumpkin JPSmit's Avatar
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    Re: reason for it said 1500 has cooling (run to hot) problems?

    IIRC 76's are supposed to be set ATDC - though mine is BTDC. Also, the vacuum is Vacuum Retard not advance. Jeff (advanced distributers) suggested I disconnect the vacuum. I did and think it runs better - and cooler.
    John-Peter Smit
    1976 MG Midget
    1969 Vauxhall Viva GT
    1958 Fiat Multipla (Barn art)

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    Re: reason for it said 1500 has cooling (run to hot) problems?

    I thought what is shown in the manual for '76 to be set ATDC is for emission concerns (my emission components are removed). Why would other years for the 1500 be set at 10deg BTDC?

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    Re: reason for it said 1500 has cooling (run to hot) problems?

    That's emissions BS, mine is set at 12 BTDC but I have 7.5 compression. I'd say 10 is a good starting point. If you want it to run like crap and have no power then set it ATDC.

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    Re: reason for it said 1500 has cooling (run to hot) problems?

    Quote Originally Posted by JPSmit View Post
    IIRC 76's are supposed to be set ATDC - though mine is BTDC. Also, the vacuum is Vacuum Retard not advance. Jeff (advanced distributers) suggested I disconnect the vacuum. I did and think it runs better - and cooler.
    IIRC all 1500's are spec'd ATDC. You can find a vac advance diaphragm and convert yours. I did but I can't use it anymore because of the DCOE. I need to hook that thing back up.

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    Re: reason for it said 1500 has cooling (run to hot) problems?

    Already have a vacuum advance setup.

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    Re: reason for it said 1500 has cooling (run to hot) problems?

    Quote Originally Posted by recordsj View Post
    Already have a vacuum advance setup.
    You sure it's advance and not retard?

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    Re: reason for it said 1500 has cooling (run to hot) problems?

    Quote Originally Posted by kellysguy View Post
    You sure it's advance and not retard?
    I have a hose connected to the bottom of the Weber DGV carb to the distributor. When I rev the engine I will notice (with a ignition timing light connected), ignition is happen at a higher degree of BTDC. So I am thinking I have a vacuum advance. My distributor is https://www.mossmotors.com/Shop/View...eIndexID=76120

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    Re: reason for it said 1500 has cooling (run to hot) problems?

    Yep, that's an advance can. If the hose hooks up on the front it's advance, on the back side is retard. https://www.ebay.com/itm/MG-Midget-1...-/280904024436

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    Re: reason for it said 1500 has cooling (run to hot) problems?

    Quote Originally Posted by kellysguy View Post
    Yep, that's an advance can. If the hose hooks up on the front it's advance, on the back side is retard. https://www.ebay.com/itm/MG-Midget-1...-/280904024436
    what is the front and what side is the back?

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    Re: reason for it said 1500 has cooling (run to hot) problems?

    Quote Originally Posted by recordsj View Post
    what is the front and what side is the back?
    The back is the part behind the front, which us just in front of the back. O.K, the round thing, right. The back part is the half that is on the distributor side. The front is the other side. It it plugs onto the front, it's advance; the rear, retard.

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