Coolant temp gauge ?

hunterdan

hunterdan

Well-Known Member
Joined
Apr 13, 2009
Location
Morganton,NC
I've got a 87 YJ with an 83 CJ 4.2L engine.
Coolant temp switch broke when doing head gasket. It's the brass screw in type with a single hot wire to top of switch. It's located on driver's side rear of head. Temp gauge.worked before new head and gasket but never got above 170.
Problem is with a cold engine and new temp switch after cranking it shows 120 immediately.
I thought maybe air was in system due to the new head and fluids. I removed switch from head and got a fountain of coolant.
I was trying to burp the system but gauge shows to high before I can get to point of thermo opening. Here's some basic info,
New head and gasket
New thermo
New temp switch (tried 87 & 83 year switch)
Radiator full, overflow tank to full line, intake and all hoses full, heat valve open,fan off, all grounds sanded and good as switch grounds through block.
I did drill a tiny hole in thermo lip at top to avoid air being trapped
Every time temp gets to high I turn it off because I worry I'll blow new head gasket I did jump a ground to switch housing while positive wire attached and it pegs the switch to past max 260.
Any ideas?
 
Those switches have different voltage ranges.
I wonder if you have the wrong range switch.
Easy cheap low tech check.
Removed radiator cap and let idle until you get to a mid to high temp. Then put a cheap thermoeter down in teh radiator neck and see if the temp matches the gauge
 
Ron said:
Those switches have different voltage ranges.
I wonder if you have the wrong range switch.
Easy cheap low tech check.
Removed radiator cap and let idle until you get to a mid to high temp. Then put a cheap thermoeter down in teh radiator neck and see if the temp matches the gauge
Click to expand...
Thanks, good idea. My 83 switch starts out high the other for 87 year doesn't move except when key is engaged.
I thought I let it get hot enough to kick on thermo but no flow Checking temp of water would be nice if thermo is opening but what if it's not? Maybe I should remove the thermostat until I can figure out the temps?
 
I use an IR thermometer to check temps at the thermostat housing OR the front of the head where the sensor goes.
You should also be able to see the thermostat open on the gauge when starting from a "full cold".
My YJ would swing just past 210 on the gauge and swing back to 190 when the thermostat fully opened.
 
you can check the thermostat in a pot of water and a thermometer. heat the water on the stove with the thermostat in it, and measure the temp that it opens. if the water is boiling and it isnt open, its bad.
 
grapehead said:
Sounds like the wrong sending unit for the application
Click to expand...
Yeah right?
Autozone/advance...have given me different part numbers depending on which worker I'm talking to.
I called jeep dealer parts guy and he said it's no longer made for 83 or 87 models.
 
hunterdan said:
Yeah right?
Autozone/advance...have given me different part numbers depending on which worker I'm talking to.
I called jeep dealer parts guy and he said it's no longer made for 83 or 87 models.
Click to expand...
Its not, from Jeep.
Certainly is from aftermarket.

Part of the issue is going to be figuring out what sensor you need. Its going to have to fit the 83 block, but output to the 87 gauge, assuming you didnt change the gauges when you did the motor swap.
The gauge has a voltage operating range. It is possibly different between the motor and the body.

Additionally in 1987 you could get a YJ with a gauge or an idiot light only.

Looking at a service manual saved on the hard drive in 87 you have the follwoing OEm temp senders depending on gauge trim or part # supercede:
2131122, 3173363, 3177594, 3179953, 941841, J3177594, J3179953,

Not to be a dick, but this is what I find so humorous about people mocking parts store guys asking about what engine for wiper blades or similar.
The flip side is you get a customer in here with a frankenstein asking for parts to solve their problem when they lack the complete picture to provide the asnwer.

If you can tell me what gauge you have in the Jeep then I can cross reference the sender for you.
Or...assuming you still have the old broke one it should have a cast in part number you can cross reference.
 
Ron said:
Its not, from Jeep.
Certainly is from aftermarket.

Part of the issue is going to be figuring out what sensor you need. Its going to have to fit the 83 block, but output to the 87 gauge, assuming you didnt change the gauges when you did the motor swap.
The gauge has a voltage operating range. It is possibly different between the motor and the body.

Additionally in 1987 you could get a YJ with a gauge or an idiot light only.

Looking at a service manual saved on the hard drive in 87 you have the follwoing OEm temp senders depending on gauge trim or part # supercede:
2131122, 3173363, 3177594, 3179953, 941841, J3177594, J3179953,

Not to be a dick, but this is what I find so humorous about people mocking parts store guys asking about what engine for wiper blades or similar.
The flip side is you get a customer in here with a frankenstein asking for parts to solve their problem when they lack the complete picture to provide the asnwer.

If you can tell me what gauge you have in the Jeep then I can cross reference the sender for you.
Or...assuming you still have the old broke one it should have a cast in part number you can cross reference.
Click to expand...
Thanks for taking the time to look up that data.
My jeep is definitely "custom"

I have read that CJ gauges were a different animal than the YJ. I'm pretty sure my gauges are original to the 87 body but got both 83 & 87 senders just in case.

I agree about parts store employees. I always go along with whatever they require. It has saved me extra trips in the past.
 
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