lt4 conversion.....coolant sensor location problem
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From: spring tx
lt4 conversion.....coolant sensor location problem
i did a conversion installing a lt1 out of a 95 with lt4 top end swap all into a 72 nova.....now i am using a autometer coolant temp gauge and sending unit..first i installed this into the drivers side cylinder head and it reads about 50-60 degrees higher than what the ecm reads when i took it to a shop and pluged it into their scanner. i then took vettedans example in his website and did a swap to a 95zr1 coolant sending unit in the water pump and used the extra lead...when the zr1 sending unit would read 150 the auto meter unit would read 210 when the autometer unit would read 250 the zr1 unit would read 155-160......does anyone know how to correct this or where to locate a sending unit to get a proper reading, like can i tap the water pump somewhere and install the sending unit....would i get a good reading if i installed a t-fitting where the sending unit that the ecm uses goes into the water pump. i have a seperate setup to control the fans on my car, does the ecm need the sending unit for anything other than fan control? 
[Modified by blue72lt4sc, 10:10 PM 7/4/2004]
[Modified by blue72lt4sc, 10:10 PM 7/4/2004]
Thread Starter
Instructor
Joined: Oct 2002
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From: spring tx
Re: lt4 conversion.....coolant sensor location problem (Twin_Turbo)
just a little.....the problem is the different ohm ranges on the sending units..that and the lt1s are reserse cooled....but i think that if i tap the thermostat housing for a sending unit it might work,
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From: Sometimes I wonder... why is that frisbee getting bigger? Then it hits me.
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St. Jude Donor '06
Re: lt4 conversion.....coolant sensor location problem (blue72lt4sc)
hey bud the stock sending unit in the drivers side head should work, however there is a custom piece that another member used with two pigtails so he could run the gauge and also a lead to the ECM, I am running an LT1 out of a 92 in my 77 but have yet to get my temp gauge working, I have a few other issues to sort out first then I will be working on a total aftermarket gauge install. I am sorry I can't remember the guys name or his webpage , someone wanna drop the link if they can remember??
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From: Living in the Hartland
Re: lt4 conversion.....coolant sensor location problem (blue72lt4sc)
The sensor and gauge might be calibrated diff, you could try getting a temp gauge and sensor from an LT1 car and graft the stock 72 face onto it. I did that with an autometer gauge but the calibration is diff so it reads a little off.
[Modified by Fevre, 12:05 PM 7/5/2004]
[Modified by Fevre, 12:05 PM 7/5/2004]
Thread Starter
Instructor
Joined: Oct 2002
Posts: 214
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From: spring tx
Re: lt4 conversion.....coolant sensor location problem (Fevre)
im using the sending unit that came with the autometer gauge...the problem is, is that since there in no other place to install a sending unit in the water pump i installed the sending unit in the cylinder head but since an lt1 is reversed cooled the reading from the sensor being in that location it reads about 50 degrees off.......i also tried installing a zr1 sending unit and used the extra pigtail end but it read totally different ,, vette dan did this but he was using a stock c3 gm temp gauge, not after market and put a 150ohm resistor inline to correct the differences...but the autometer sending units ohm range is too different from any gm unit....so today i taped a hole in my water neck and installed the sending unit in there and it seems to give a more realistic reading.we'll see tomorrow what i plug in my comp. to compare ecm and gauge readings.
