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Author Topic: Overheating - Newbe needs help
Howard
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Region: NORTHEAST
Car #: 66
SMIM: SM
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I bought a new (to me) well used 94 SM last fall. Finally got it on the track At Pocono (east) yesterday. First session with air temp about 45 coolant temp was about 200 degrees. 2nd session air temp up to 60. 10 laps and coolant overflow reservoir full and blowing out overflow - serious over heating. Got it cooled down, 2 laps into next session coolant at 220 and rising. Loaded on trailer. Oil pressure 45-50 with revs above idle.
Previous owner reports never had the problem. No leaks to be found. Has aftermarket radiator (unknown brand) with some fin damage to lower section but no leaks. 12 lb cap. Open the cap and rev the engine - lots of flow visible. Still had 50/50 antifreeze mix in system. NASA doesn't mind.
Should I just spring for a new radiator or is there something else to look for. Also fan never came on! Where's the switch for that?

Howard

Cajun Miata Man Verified Driver
Overdog Driver

Region: Houston; SWDIV
Car #: 15
Year : 99
Posts: 680
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When you had the cap off and revved the engine, did you notice any amounts of vapor bubbles coming to the opening?

--------------------
James York


sponsored by:
Stan's Auto Center, Lafayette LA
powered by:
East Street Racing, Memphis TN
set up guru:
Gilfus Racing, Austin TX

Mark de Regt Verified Driver Made Donation to Website
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Region: NWR/Oregon; ICSCC
Car #: 70
Year : 1991
Posts: 1111
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Howard,

The same thing happened to me when I bought a used SM.

In my case, the problem seemed to be that the car had sat for a while, and mung (that's a racing term of art) had settled in the radiator, seriously compromising its ability to cool.

I used it as an excuse to buy a used Koyo aluminum radiator, which I am now (three years later) replacing with a fat Koyo radiator.

You can take the radiator to a radiator shop for diagnosis and repair, which typically isn't expensive if you take the radiator out of the car.

Depending on what type of radiator it is, I'd be inclined to not throw good money after bad and buy a good radiator (like a fat Koyo or Springfield Dyno). It gets hot in the Northeast.

Also, for future reference, antifreeze has two very bad characteristics for racers: It's very slippery if you spill some on the track, and it's a lousy coolant. Much better to use straight water or water mixed with Water Wetter.

Vick Verified Driver
Do they sell spec training wheels?

Region: NYR
Car #: 12
Year : 1991
Posts: 620
Status: Offline
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Howard:

Welcome to the North East and running a SM with NASA.

Are you going to be at NJMP next weekend? If so talk to Tony Senese, he's a great miata guy and has run a bunch of different radiators.

I run a radiator from an automatic transmission car and have had no problems with it. Going into my third year with the car now.

Good luck, there's lots of good information out here.

--------------------
http://www.volko.com

d mathias Verified Driver Made Donation to Website
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Region: OVR
Car #: 88
Year : 1991
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What's the condition of the cap? New?

P.S. Better read your CCR, NASA does mind.

Howard
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Region: NORTHEAST
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wow. you guys are fast. Thanks for the help.
Jim - No bubbles or vapor - the visual flow check is with a cool engine. Are you thinking head gasket? It only took about a quart to refill it after the boil over.

Mark - Is the Koyo an easy install or will I need to make some mods? I'm aware of the antifreeze on the track problem but the forcast for the night before the track session was low 30's and up in the mountains maybe 20's. Didn't need a frozen block. I always thought an antifreeze mix was a better coolant - higher boiling point. We use it in all our trucks and equipment on the job and they work in pretty extreme conditions. It's nice to learn something every day.

Mark de Regt Verified Driver Made Donation to Website
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Year : 1991
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Howard,

Antifreeze does make for a higher boiling point, but it is a poorer coolant, in the sense that it exchanges heat in the radiator less efficiently than water alone (and even moreso compared to water with Water Wetter). It's better for road vehicles, and construction vehicles, for the higher boiling point and the anti-corrosive aspects.

The thin Koyo required no surgery to install. The fat Koyo, as far as I can remember, also required no surgery to install. I understand that the SD radiator requires surgery.

Radiators can be changed in SCCA, subject to some restrictions. You should make sure that whatever body you will race in allows whatever you might be planning to do.

Howard
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Region: NORTHEAST
Car #: 66
SMIM: SM
Posts: 40
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Yeah - I know NASA does mind. Just being a wise a**. It was an open track day and I'm pretty sure the HPDE guys didn't drain their antifreeze, especially the Porshe guys.

Vick - Thanks for the Welcome. Can't make NJ. Most of my available weekends are later in the summer. Hope to meet you somewhere. You'll recognize me by my bumper sticker. The fast cars are very careful going around me

Howard

Terry Whitlock Verified Driver
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Region: BUCCANEER
Car #: 23 SSM, 36 SM
Year : 1992, 1990
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You did not mention if you were running a thermostat. Since the car sat for a time it is possible that the thermostat may be sticking and limiting the flow. I have seen such problems a number of times.

--------------------
Terry Whitlock

Mark de Regt Verified Driver Made Donation to Website
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Year : 1991
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Howard, another overheating problem I had was when a little hose was not properly tightened, and there was a very slow leak onto the top of the head. Not enough leak to notice coolant loss, and it evaporated immediately, so no puddle. Found it with a pressure test.

Cajun Miata Man Verified Driver
Overdog Driver

Region: Houston; SWDIV
Car #: 15
Year : 99
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quote:
Originally posted by Howard:
wow. you guys are fast. Thanks for the help.
Jim - No bubbles or vapor - the visual flow check is with a cool engine. Are you thinking head gasket? It only took about a quart to refill it after the boil over.


Yes, I was thinking maybe a head gasket. But it sounds like that is not the case.

--------------------
James York


sponsored by:
Stan's Auto Center, Lafayette LA
powered by:
East Street Racing, Memphis TN
set up guru:
Gilfus Racing, Austin TX

Keith in WA Verified Driver Made Donation to Website
Pack Fodder

Region: NWR / Oregon
Car #: 88
Year : 95
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To test for the thermostat, take it out and heat it in water on the kitchen stove and see what temp it opens. Plenty of flow though so probably not it but easy to check.

Better than a visual check, a $20 block test kit available from NAPA will test for combustion gasses getting in your cooling system and forcing coolant out. Very simple test. It might not be a lot of coolant loss and they can be small bubbles that are hard to see. My truck died that way. Only being down a quart the temp would spike.

--------------------
Keith Novak
(Will work for tires)

Dennis Clark Verified Driver
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Region: SFR
Car #: 27
Year : 1994
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Howard,

The fan should come on at 207. You can test the fan by giving it 12 v at the connector. If the fan motor is ok you can test the circuit by jumping TEN to GND in the data link connector, then turn ignition ON and press accelerator pedal.

Dennis

--------------------
3D Racing
Team Scrappy, car # 27

Howard
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Region: NORTHEAST
Car #: 66
SMIM: SM
Posts: 40
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Thanks Guys

I think I found the problem - intermitent thermostat function. Dropped it in hot water and it works sometimes but not always. The thermostat looks a little bent. Time for a new one.

Still working on fan problem. Works with power jumped to fan motor.

Dennis, I've got a lot to learn. Where's the "data link connector?"

Howard

Muda Verified Driver Made Donation to Website
ComingToAMirrorNearYou

Region: WDC
Car #: #23
Year : 1991
Posts: 642
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aka - Diagnostic Port

--------------------
Muda Motorsports
"We're all here 'cause we're not all there."

Dennis Clark Verified Driver
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Region: SFR
Car #: 27
Year : 1994
Posts: 43
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Hi Howard,
It's on the left fender under the hood. Black rectangular with a cover that says DIAGNOSIS. You can test lots of stuff by jumping to ground with a paper clip or a U of safety wire.
Everybody jumps F/P to GND to run the fuel pump when you turn the key on, to test pump or to drain tank through the fuel port.
Dennis

--------------------
3D Racing
Team Scrappy, car # 27

   

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