Stock coolant temp sensor in upper radiator hose?
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From: St Simons Isl, GA
Stock coolant temp sensor in upper radiator hose? I'm swapping an LS1 into a '75 Corvette convertible, and I'm needing a solution for my stock water temp sensor. I know a lot of guys drill and tap the head or a brass freeze plug, but the engine is already in the car and I was hoping I could come up with a coupler that I could mount the sensor in and just put it in the upper radiator hose. Autometer sells a few couplers like this, but they're tiny and they're meant for their sending unit, which is also really small.
Anyone done anything like this? Or put it in the heater hose? What did you use for a coupler?
Thanks guys.
Anyone done anything like this? Or put it in the heater hose? What did you use for a coupler?
Thanks guys.
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Joined: Jul 2005
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From: Beebe, Arkansas
Or remove the two pin CTS and use the 98 Camaro three wire CTS coolant temp sender. GM P/n 12551708. Your plug from the PCM plugs in it and has a third wire to go to the stock GM gauge in your cluster. You can even it pig tail adapter harness making it plug and play off ebay.
My C3 temp sensor was 1/2" NPT. That is the size of the freeze plug ID if you drill and tap it. I checked out the 98 3 wire sender/sensor. It's way off from the C3 gauge range. The addition of a resistor would make it reasonably close though. Just drill and tap the freeze plug.
Thread Starter
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From: St Simons Isl, GA
What would I need to do for a resistor to make it work? I'm at the point where I have so much installed in the engine bay I don't know if I'll be able to get to a freeze plug to drill and tap. I know, poor planning, but its where I'm at. And I'd be happy if I could just get the stock gauge reasonably close.
The block heater plug unscrews from the block. There is one on either side. You can buy a new plug at a GM dealer for like $12 and modify it before you begin the project. They drill out perfectly to 1/2 NPT. I had to use adapters to fit a metric jap sensor.
If you bought one of those upper radiator hose couplers with a 1/4 in pipe tap, it is a simple matter to take it to local weld shop and have them weld in a 1/2 NPT bung.
A third option is the freeze plug in the end of one of the heads. You could easily weld a bung on one of those too.
If you bought one of those upper radiator hose couplers with a 1/4 in pipe tap, it is a simple matter to take it to local weld shop and have them weld in a 1/2 NPT bung.
A third option is the freeze plug in the end of one of the heads. You could easily weld a bung on one of those too.
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The block heater plug unscrews from the block. There is one on either side. You can buy a new plug at a GM dealer for like $12 and modify it before you begin the project. They drill out perfectly to 1/2 NPT. I had to use adapters to fit a metric jap sensor.
If you bought one of those upper radiator hose couplers with a 1/4 in pipe tap, it is a simple matter to take it to local weld shop and have them weld in a 1/2 NPT bung.
A third option is the freeze plug in the end of one of the heads. You could easily weld a bung on one of those too.
If you bought one of those upper radiator hose couplers with a 1/4 in pipe tap, it is a simple matter to take it to local weld shop and have them weld in a 1/2 NPT bung.
A third option is the freeze plug in the end of one of the heads. You could easily weld a bung on one of those too.
I tried the drill/tap the waterpump route, but the alum is too thin to get any good threads on. I ended up putting my sensor in the heater core hose right out of the water pump. Used a 1/2" brass tee with 1/2 fpt on the tee and screwed the sensor into that. Works perfect.
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