3 replies to this topic

[declfc]

Does anyone has experience drilling the hole on the (late type) cylinder heads for the coolant temperature sender.

I've done a good search but I cant seem to find a definitive answer. From what I can gather its a two stepped hole.

The top hole has the thread in it (5/8 UNF) then the bottom hole is for the tip of the temperature sensor to go through

and the temperature sensor seals on the seat between the two holes. 

Does anyone have anymore information than this? Depths, dia of bottom hole.

 Temp1.jpg   80.04K   18 downloads

 Temp3.jpg   8.55K   0 downloads

[Spider]

I've done a number of them.

 

I drill right though first with a drill for bulb part, then drill in deep enough for the seat with a 14.7 mm (or 37/64"). I then finish the seat with a 90⁰ counter sinking bit, then tap at 5/8" UNF..

 

Tip: Use a drill stand or mill for all operations, including starting the thread off and when drilling with the 14.7 mm drill, use a depth stop to avoid embarrassment. 

[maccers]

Hmm, mine was drilled in the traditional position and I recall the machine shop using a single drill for the hole then taping it with a manual tool. I have a capillary gauge so have the extended insert type fixing, which seals perfectly.

[slidehammer]

You could always use a sandwich plate between the thermostat housing and the head (pre drilled and tapped for a sender unit). Rather risk messing up your head if you are worried.