Mechanical temp gauge

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Apr 25, 2008 | 06:17 PM

Bluebomber94

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Mechanical temp gauge

Hello everyone, I just purchased a mechanical temp gauge for my truck, 4.9 300 I6. just wondering if anyone can tell me where to install the sending unit. I've read that it is on the block on the passenger side but can't seem to find it. Can it be installed at the thermostat or is better at the block? Also the instructions says you can use a T adapter which I have but I have also read that you can't use a T like on the oil pressure gauge because the temp sending unit needs to be in the flow of coolant, is this correct? any help is appreciated.

Apr 25, 2008 | 07:28 PM

fmc400

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From: Austin, TX

You cannot use a T-adapter on coolant sending units, because of the reasons you stated. The sending unit goes on the passenger side of the block, right below the head, toward the back. See the picture below. Sorry about the size.

Apr 25, 2008 | 07:40 PM

Bluebomber94

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Ahh now I see, Thanks very much a picture is definitely worth a thousand words.

Apr 25, 2008 | 07:47 PM

1982fordf100

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From: SE, Michigan

I kept my original one on the back side of the block and added the after market sending unit next to the thermostat. I had an extra spot on the thermostat housing that used to have an old vacuum ported switch that wasn't needed after my engine rebuild. That is the point where the coolant is going to be the hottest just before it leaves the engine and goes into the radiator.

Apr 25, 2008 | 08:10 PM

Bluebomber94

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yeah mine doesn't have an extra port at the thermo, I wish it did, it would make it alot easier. If I had the machining skills I thought I might be able to drill and tap a new port for the original sending unit. So I will try it on the block and I assume the gauge on my instrument cluster with just tell me when the thermostat is open or closed.

Apr 25, 2008 | 08:41 PM

1982fordf100

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You could always check the local junkyard to see if there is a thermostat housing that has the extra fitting on it. It comes just off the side where the heater hose has the extra extension on it. Almost all 300's I have see have the threaded spot for it even if it has a plug in it, vacuum port switch or even the efi 300's had an extra temp gauge switch in it. It shouldn't be more than a $5 part too.

Apr 26, 2008 | 09:06 PM

63redtudor

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I have the opposite set-up as 1982fordf100 (original sender/gauge on the thermostat housing), for no other reason than I was just cirious. I've decided to keep it this way as I've had stuck thermostats in the past & its kinda cool to be able to watch it open.
Edwin