Will high temp reading shut engine down?
Thread Starter
Instructor
Joined: Dec 2006
Posts: 125
Likes: 0
From: Kemah Texas
Will high temp reading shut engine down?
92 Vette LT 1 mostly stock, Moroso opti. I am trying to diagnose an engine quit when hot problem. Typical problem like many of the threads, engine dies when hot. Replaced ICM & Coil (GM parts) but problem continued. Noticed today that just before engine died digital read out went between 120 & 230 real quick. I am planning on replacing the temp sending unit but wonder if there a safety feature built in that shuts engine down if sending unit show engine hot (like oil pressure when low)...
Instructor
Joined: Sep 2004
Posts: 208
Likes: 1
From: Lawrenceville GA
Same issue in the past. Mine was the ecm. Got hot, solder joints separated. Putting a bag of ice on it while hot at idle and would never die. Sent it off to be rebuilt, all has been fine for 10 years. Only now you can get a rebuilt ecm from most major auto parts guys and with a warranty for less than I paid for the rebuild. Post what you find......I don't believe high temps will shut you down
Race Director
Joined: Oct 2005
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From: Rolla Missouri
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Thread Starter
Instructor
Joined: Dec 2006
Posts: 125
Likes: 0
From: Kemah Texas
temp on digital gauge looks like a slot machine just after you pull the handle. when it does this engine quits! analog gauge steady. infrared gun shows 192. car only driven 1500/2000 a year. first time it happened was in Feb. towed in to mechanic who specialty is HP cars. after a week testing & driving, nothing, no codes. took a chance it was ICM or coil, replaced both but problem continued. replacing temp sending unit this week. next will be ECM but hate throwing money at repairs not working, in addition to tow charges... read many post about this problem and doesn't seem to be a simple solution. good pressure at fuel rail and no gas smell. all gauges working. original ECM with 174K miles.
Last edited by easy2no; Jul 19, 2015 at 07:17 PM.
Melting Slicks
Joined: Jan 2009
Posts: 3,181
Likes: 286
From: Puyallup Washington
Same problem with my 1991, 85000 miles
When the digital temp gets to around 185 it then jumps to about 261 and the car shuts off. It will not restart until the gauge goes back down to about 185. Then restarts and runs fine until the temp goes up to 261. All this time the analog gauge stays right where it should be.
I have replaced the ICM, and the dist. cap and rotor as they looked like they needed it. Because it was easy and cheap, I replaced the coolant temp sensor at the front of the engine. That made no difference.
I will now have to get out my voltmeter and see if I can confirm it is the ECM before sending it off for repair.
I will let you know what I find.
I have replaced the ICM, and the dist. cap and rotor as they looked like they needed it. Because it was easy and cheap, I replaced the coolant temp sensor at the front of the engine. That made no difference.
I will now have to get out my voltmeter and see if I can confirm it is the ECM before sending it off for repair.
I will let you know what I find.
Burning Brakes
Joined: Apr 2009
Posts: 1,228
Likes: 10
From: That one city...you know that one. Idaho
When the digital temp gets to around 185 it then jumps to about 261 and the car shuts off. It will not restart until the gauge goes back down to about 185. Then restarts and runs fine until the temp goes up to 261. All this time the analog gauge stays right where it should be.
I have replaced the ICM, and the dist. cap and rotor as they looked like they needed it. Because it was easy and cheap, I replaced the coolant temp sensor at the front of the engine. That made no difference.
I will now have to get out my voltmeter and see if I can confirm it is the ECM before sending it off for repair.
I will let you know what I find.
I have replaced the ICM, and the dist. cap and rotor as they looked like they needed it. Because it was easy and cheap, I replaced the coolant temp sensor at the front of the engine. That made no difference.
I will now have to get out my voltmeter and see if I can confirm it is the ECM before sending it off for repair.
I will let you know what I find.
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
STUPID QUESTION:
Are you certain that the engine coolant system has been filled correctly...and is flowing correctly...and ALL of the air has been bled out of the system as per GM's instructions by opening up the fitting on the thermostat housing????
And by flowing correctly,,,,because I run into this A LOT. is that small hose that is attached to the TOP RIGHT side of the radiator....that goes to the expansion tank....HAS to be flowing water!. So when the engine is cold....remove the radiator cap and crank the engine and see if you can see a good flow of coolant mix coming from this hose. IF NOT...shut off the engine and remove this hose assembly ends an blow them out very well.
I have to do this more frequently due to age on these hose assemblies.
And are you sure the radiator cap is GOOD? Has it been tested?
Have you had an opportunity to hook a scanner to your car and see what happens when it dies??? or if it is dead...and trying to get it cranked...what the readings on the scanner show???
DUB
Are you certain that the engine coolant system has been filled correctly...and is flowing correctly...and ALL of the air has been bled out of the system as per GM's instructions by opening up the fitting on the thermostat housing????
And by flowing correctly,,,,because I run into this A LOT. is that small hose that is attached to the TOP RIGHT side of the radiator....that goes to the expansion tank....HAS to be flowing water!. So when the engine is cold....remove the radiator cap and crank the engine and see if you can see a good flow of coolant mix coming from this hose. IF NOT...shut off the engine and remove this hose assembly ends an blow them out very well.
I have to do this more frequently due to age on these hose assemblies.
And are you sure the radiator cap is GOOD? Has it been tested?
Have you had an opportunity to hook a scanner to your car and see what happens when it dies??? or if it is dead...and trying to get it cranked...what the readings on the scanner show???
DUB
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Race Director
Joined: Mar 2015
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When it's up to temp jack up the right rear of the car carefully open the radiator cap and fill letting the air bubble out. I like this better than the bleeder screws and takeing a chance getting the opti wet.
Heel & Toe
Joined: Jul 2015
Posts: 17
Likes: 0
Will high temp reading shut engine down?
230 is hot period most vettes seem to get hot but your only 15deg away from the temp that alum heads can warp. Replace the temp sensor probe on the front of the motor as it's the one that communicates with computer. Also check the wiring at the sensor as it sees alot of heat. Just my experience
Heel & Toe
Joined: Jul 2015
Posts: 17
Likes: 0
Will high temp reading shut engine down?
I just replace both on my 96 lt1 and in town here in ga at 97F' my car runs between 192 to the hottest 213. I did reprogram my fans to turn on at 215 instead of factory setting of 227. Good luck
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
You wont get the opti-spark wet when bleeding the air out as a GM as described. it is not like you are allowing a gallon of coolant to come out of the bleed fitting....and that is what that made paper towels for. I have never gotten an opti-spark wet and I have done countless LT-1/LT-4's
And running the engine until it reaches operating temperature when you can have an air pocket at the thermostat....I just don't understand why you do it that way.
To each his/her own.
DUB
Race Director
Joined: Mar 2015
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What???? You are bold...that is for sure.
You wont get the opti-spark wet when bleeding the air out as a GM as described. it is not like you are allowing a gallon of coolant to come out of the bleed fitting....and that is what that made paper towels for. I have never gotten an opti-spark wet and I have done countless LT-1/LT-4's
And running the engine until it reaches operating temperature when you can have an air pocket at the thermostat....I just don't understand why you do it that way.
To each his/her own.
DUB
You wont get the opti-spark wet when bleeding the air out as a GM as described. it is not like you are allowing a gallon of coolant to come out of the bleed fitting....and that is what that made paper towels for. I have never gotten an opti-spark wet and I have done countless LT-1/LT-4's
And running the engine until it reaches operating temperature when you can have an air pocket at the thermostat....I just don't understand why you do it that way.
To each his/her own.
DUB
I have seen the bleeders back off and leak after bleeding killing the opti.
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
I still would not every crank and warm up a LT-1 /LT-4 unless I knew for a fact that all the air is out of the thermostat housing. I follow the outlined material that GM put in the service manual...due to the coolant system is reverse flow. I just can not take the chance....and what it takes to do it like what GM states...has never caused me a problem.
DUB