i have and 88 f150 with a 300-6 that i recently purchased a set of aftermarket mechanical gauges for. when installing the temp. sending unit i found that the aftermarket unit was too long for the threaded hole in the block (it hits an obstruction inside the block). it's a sealed unit all the way back to the gauge so changing sending units was out of the question.

i made a "T" fitting from brass fittings from the local hardware store and installed both the factory electrical sending unit and the mechanical aftermarket one. now it seems i'm getting a very low temp. reading from both gauges even after i'm up to operating temp.

i put the original electrical unit back in the block and the reading on the factory gauge seemed alot more believable.

any suggestions on where to install the aftermaket sender directly in the block? i've heard of having a freeze plug threaded or drilling a hole in one and welding a nut of the appropriate size to it. bad idea?

thanks for your time.

 

Does the thermostat housing have a hole with a plug in it? That's a good place.

You could probably get one off a junker if not. Ford liked to use the T-stat housing for sensors and vacuum switches.

 

Yes, but there is a temp. sensor for the computer installed there.
thanks anyway

 

What kind of gauge are you using? Most reputable gauges will fit no problem. I'm using the cheap ones from Autozone, and they fit fine.

T-ing a temp gauge never works. The coolant doesn't flow through the T, so you'll have false readings.

To fix your problem, I would go with a different gauge.

 

The gauges came from Summit racing (they are the manufacturer as well). the sending unit probe is about 1/4" too long, it will not seat fully in the threaded hole in the block.

 

In that case, I am very surprised. At any rate, I know for a fact that the sunpro gauges fit.

 

The gauges seem to be of good quality, I'm happy with the oil pressure gauge, it went in no problem. I'm still thinking about the freeze plug idea for the temp. sensor.

 

I put mine in a tee in the heater hose. Works fine.

 

is the gauge specific for the engine/truck or is it generic? if its specific the you should contact summit about it before jimmy rigging something up

 

No, it's just a generic gauge kit - temp. and oil pressure

 

Napa has a large variety of adaptors, so you might be able to space the gauge out just 1/4-1/2", to keep it from touching. FWIW, I have mine in the water neck, but I had to space it out. It went in without bottoming, but I had no heat. Turns out it very nearly blocked the passage off.