Overheating problem solved

Just like I read somewhere (maybe the FAQ) removing my front license plate makes my Miata temp gauge run from dead center to maybe 5/8ths
and no more. Before it would climb to the top. Highly recommended.
JJ
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Don't you think something is plugged or restricted somewhere? the license plate trick is something to get you into town, not defer an aging radiator or defective thermostat. YMMV
<me> wrote in message

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Keep looking. You found a band-aid, not the actual cooling problem. The gauge of a U.S.-spec Miata should stay a needle width left of center, even in the desert with a plate and foglights in the mouth (BTDT).
If your car is more than 5 years old, your radiator may be partially clogged and ready for replacement. Or one of your fans may not be working properly all the time. Or your cap doesn't seal. Or your thermostat is stuck. Or you have more than 50% antifreeze in the system. Or your heater hoses are kinked.
Find the cause and fix it. Then you can put the plate back where it belongs. :-)
--
Lanny Chambers, St. Louis, USA
'94C
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A license plate attached to the vertical struts inside the mouth is still several inches away from the AC condenser, so nothing is blocked. At speed, the mouth is probably the highest-pressure area on the car, and flow through the radiator is a matter of pressure differential, not direct "impact" of incoming air--the air *will* move through the radiator regardless, because it has nowhere else to go. At subsonic speeds, the "ram" effect is just advertising drivel.

Been there, done that. Once you fix your cooling problem(s) and restore the system's original capacity, the gauge won't budge at all, no matter what stress you inflict on it. Until then, removing the plate is a good coping strategy...until the cooling system deteriorates further and exceeds your ability to apply band-aids.
--
Lanny Chambers, St. Louis, USA
'94C
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me <> wrote:

Well, I'll be able to add another "data point" to the debate sometime next week. In Switzerland, the default position for the plate (smaller than US plates) is in the mouth. I never had problems, but last week driving to Italy at high speed, over mountains, in 36C weather, I *did* notice the gauge creep up a bit. Last weekend I had the misfortune to run over a car at high speed late at night (or rather, the cat had the misfortune to be run over by me, I guess) which (a) removed my front plate for me and (b) smashed the hell out of my 9 year old radiator. I found the plate, the radiator is being replaced, and the weather predictions are sunny and warm for next week, so when my car is back together, I'll see if the better cooling system helps.
Stephen
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Hay Lanny, I didn't see anything wrong with Leon's explanation ! It was very easy to follow & covered the subject, what else could you want ? <G> :-)
Bruce RED '91 :-)
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Lanny,
How did you diagnose that dead spot on the fan commutator?
John ('94A?, white, hardtop, Arizona, intermittant very high temp reading with a/c on and ambient over 100f)
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wrote:

[Please don't email people without supplying a valid return address.]
Over two years of intermittant overheating, I had already replaced the radiator, thermostat (twice), and cap (twice), and removed the front plate. No joy.
I finally noticed that the coolant fan would work sometimes, but other times not. The condenser fan was fine, and that kept severe overheating at bay with the AC off, because the 1.8 ECU switches on the condenser fan as a backup if the coolant temp rises too high. But I couldn't run the AC in very hot weather.
I removed the coolant fan and connected it to a spare battery. I switched it on and off repeatedly, and saw that sometimes it wouldn't restart without a nudge. I marked one blade, and saw that it only failed if it stopped in one particular place. A query to the forum got a couple of responses from others who had seen this before (not necessarily on Miatas). At 100k miles, poopoo happens. I suppose the next big bump in the road would jiggle the fan motor past the dead spot and it would start working again, for another few cycles. Intermittant glitches make me crazy!
I bought a $40 used fan/motor from FM (a turbo customer had replaced it with a Spal fan). Problem solved. It proved to me that in hot weather a working fan is necessary, even at highway speeds.
If possible, see if borrowing a known-good fan from another Miata will fix your overheating.
--
Lanny Chambers, St. Louis, USA
'94C
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