Heat Sensor Fitting Size on a 218 Engine

[Marcel Backs]

I'm getting ready to fire up my flat six for the first time and it is not presently convenient to install the heat sending unit. Anyone know the size of plug required to temporarily plug this fitting on the motor? All the Best M

[Sniper]

Not sure this thread isn't too confusing to sort out, lol

 

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[TodFitch]

The hole in the head should be a standard pipe thread. For installing the heat sensing bulb a fitting with male pipe threads and female machine threads is screwed into the block and the gland nut on the sensor bulb presses the ridge of the bulb against the seat in the fitting in the block.

 

All this being a long way to say, remove the fitting from the head and get a pipe plug from your local hardware store.

[Plymouthy Adams]

I checked the head in the shop a minute ago and it is 1/2 NPT for the temperature adapter...the adapter itself will be straight threaded internally as the gland nut job here is to seat the bulb against the taper in the bung for a seal.  To bypass install of temp sender at this time, a 1/2 NPT plug will seal...use a bit of teflon tape....this is a non pressurized system pre 51.....so you not having to  crank it down much to seal

[Marcel Backs]

P.A. you are a walking encyclopedia on the MOPAR stuff! Thank you for saving me some time on this one. M

[greg g]

I did a make due deal to fit the 46 bulb into the 56 head.  Just got a bunch of plumbing bits that accept the larger bulb.  The caveat is that the gauge reads about 10 degrees cooler than coolant temp because it is out of the direct flow current.  Gauge says 160 thermometer shows 172 in the top of the radiator.   Your results may differ but it's easy to check.

[Sniper]

The bulb is in the back of the head probably not seeing all 6 cylinders worth of heat, whereas the top of the radiator does.  That might account for the different reading.