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Topic: Which one is Right?

in Forum: C4 General Discussion

Which one is Right?

Posted: 5/20/13 7:53pm Message 1 of 6
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Naples, FL - USA
Joined: 6/19/2011
Posts: 46
Vette(s): 1984 C4 Mild mods.85 fuelpump,Accel ignition, TCI, shiftkit, ramAir, Boshplat plugs, duels straight, VP 106 fuel mix, 1990 wheels,, Silver/Gray 1996 LT 4 Stock muffler eliminators Torch Red ZR1 Wheels
QuestionOk here we go. I have been having an overheating problem. Just had car in shop the temp sensor in the block on passenger side in rear on block was replaced. NOW temp GAUGE on dash goes to 250 and ANALOG to left of speed O reads 200. WHO is right? Mechanic said  anolog is correct shot a hose with a sensor gun o heat gun.  Hesaid gauge need to be re placed $$$$$ part of gauge oackage BUT I read that there are two sensors for them Where are they found and how do I re place them Or test them /.  Any helpCry  Thanks  guys


Wingnut
 
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Re: Which one is Right?

Posted: 5/21/13 6:39pm Message 2 of 6
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Don't think this is going to fix your problem. It looks like you have a late model C4. There's also a temp sender on the water pump housing at the front of the engine. One of the senders is for the gage and the other is for the ECU. Don't remember which one does what, though.
 
I also don't know anything about why your gages don't match. Good luck.
 
Sorry...



--  Mark

Re: Which one is Right?

Posted: 5/22/13 10:27am Message 3 of 6
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The one in the passenger cyl. head is for the temp gauge.  (single wire)  The one in the front near the thermostat housing (2 wires) is to the ECM and controls the fans. 


Re: Which one is Right?

Posted: 5/26/13 12:43am Message 4 of 6
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Vette(s): 1986 C4 Corvette Coupe, Medium Blue Metallic
Hi, have you tried to put a correct Automotive Thermometer in the cooling system when it is running & hot to determine what the correct temperature really is.  Then you address the real problem instead of relying on a gauge which may be faulty, then you can work out also which gauge is incorrect.


Re: Which one is Right?

Posted: 5/26/13 2:53am Message 5 of 6
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Vette(s): 1987 C4 convertible 350ci auto white / red / white top appx 18k mls
just some thoughts...
 
did your "250" come up just after the sensor was replaced? and did your gauges match before? this would hint at a dodgy sensor.
 
and do your fans come on, and at what temp?
 
good hunting
Wolfram



Re: Which one is Right?

Posted: 5/27/13 9:15am Message 6 of 6
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wingnut said: QuestionOk here we go. I have been having an overheating problem. Just had car in shop the temp sensor in the block on passenger side in rear on block was replaced. NOW temp GAUGE on dash goes to 250 and ANALOG to left of speed O reads 200. WHO is right? Mechanic said  anolog is correct shot a hose with a sensor gun o heat gun.  Hesaid gauge need to be re placed $$$$$ part of gauge oackage BUT I read that there are two sensors for them Where are they found and how do I re place them Or test them /.  Any helpCry  Thanks  guys

The sensor located in passenger side head is for the analog gauge only. The digital temperature uses the ECT sensor in the water pump (below the throttle body)...this is the same sensor the ECM uses to control open and closed loop operation and fuel trim. The ECM also uses this sensor to turn on the cooling fans which run in tandom on either low or high speed depending engine temperature. At the point where the digital gauge is reading 250* both fans should be running on high....Are they ?? As "Adams Apple"  mentioned in another post you made about over heating these things are known for "air" in the cooling system and can be a PIA--be sure that's not your problem.
 
As far as accuracy of the gauges..the digital gauge is the one to rely on.....my analog gauge reads 8-12* higher than my digital which is fairly typical of a C4 with the LTx engine. My ECM is programmed to turn on the cooling fans at a lower temp. then the OEM setting. My digital gauge is almost in perfect sync with when the fans come on and go off....As they should be since they're both controlled through the ECM.Smile   JMO




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