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Posted by: AvalonFal Apr 15 2008, 06:02 PM

Had the engine tin off of my '74 2.0L for repainting & decided to have a look around. Didn't like what I found. The Head Temp Sensor was broken in 2, with the bottom part still screwed into the head. I know I'll have to drill/extract it out, but any tricks to this?? Any ideas or special tools to make it go easier??
Thanks.
Paul

Posted by: Mark Henry Apr 15 2008, 06:41 PM

Get a left hand drill bit and pray...a lot.

One place you can get a set of these bits is Carquest part #CPE 32160 about $40 set.

Posted by: r_towle Apr 15 2008, 08:45 PM

Another way to do this would be to drill it out and tap it with a flat bottom tap.

get two taps with the correct thread (use your new CHT to determine the threads and pitch)
At the grinder, grind off the end of one of the taps to the point that its all thread, and no longer tapering...about 1/4 of an inch should do.

Now, step drill your way up one bit at a time to the proper sized bit for the tap.
Tap in as far as you can go with the normal tap...blow it out
then use the flat bottom tap to finish the hole.
This is a stopped hole that does not go through, so measure and drill slowly.

Put grease on the tap to pull out the shavings.
Clean the tap and re-grease it each time to get all the crap out.
when using a flat bottom tap, beware that you could trap material under the tap, force this material under pressure and crack the boss.

so keep the hole clean while you are doing this.

Rich

Posted by: alpha434 Apr 15 2008, 09:07 PM

Haha.

I professionally agree with the first post. Get a lot of WD and let it soak. Start with a small lefty, and try using a screw extractor popped into the hole.

Is there anything left above the surface? Before you try the left drill, you can try taking a short piece of 1/8 SS welding rod and a hammer and tap that thing at an angle to get it to unscrew.

Good luck!!!

I should add that drilling it out should be your last resort, but it will work. You just have to be REALLY careful to get that angle right, or you'll fuche up that hole really good. And use that 40$ left-handed drill set to do the drilling with. At some point, you'll drill past the seized portion, and it'll come out.

And use a center drill before you start any drill op.

Yeeeee!

Posted by: type47 Apr 15 2008, 09:13 PM

engine in or engine out?

Posted by: Vacca Rabite Apr 15 2008, 09:18 PM

Is there enough of it there to dremel in a slot for a flat head screw driver? I have done that before, and it works pretty well, especially if the piece has had time to soak in PB Blaster or some other GOOD penetrating oil.

Zach

Posted by: AvalonFal Apr 16 2008, 08:24 AM

QUOTE(type47 @ Apr 15 2008, 11:13 PM)

Posted by: HAM Inc Apr 16 2008, 08:44 AM

PB blaster for sure. If you do use a drill stay with the left hand bit as it might just work. And be very careful not to drill deeper than the bottom of the hole. You'll pop out in the chamber!
The threads are M10 x 1.0

Posted by: Cap'n Krusty Apr 16 2008, 09:44 AM

Decades of experience tells me that the threads are galled and you're gonna have to drill out the remains of the sensor, go oversize to the correct size, and install a Time Sert. Best to do this with the engine out. The Cap'n

Posted by: AvalonFal Apr 17 2008, 10:54 AM

QUOTE(HAM Inc @ Apr 16 2008, 10:44 AM)