I went to replace my cylinder head temp sensor. (75 1.8L with fuel injection). I squirted some Kroil penetrating oil in the hole twice in the last 2 days. I put the socket on and it starts to turn. When I pulled the socket out I only had the top of the sensor, the threads are still in the head! Do I have to drop the engine to get it out, or can't this little shit sensor be bypassed???

When mine came out, it came out with the head threads to.

I feel your pain.

I took off the injector pipes to get to my first bad sensor. If you have someone that knows how to get a drill into the remaining sensor body, you may be able to bang a square bolt remover in the drill hole and carefully back the remains out with a good wrench appropriately sized.

I doubt that you can go without it without putting carbs on it.

Good luck. I always am amazed at how people here come up with answers. Maybe mine is no good, but if it was mine, I would be buying the parts to drill a hole in the remains and try one of those square bolt removers. They are made of carbide, and you would break your wrist before you break the carbide backerouter.

Yes, I don't know the name of the damn thing. I am only HALF German.

The rest is Irish, and I killed those brain cells off in the 70's.

John

I am afraid you will need to a right angle drill to drill the pilot hole for an easy out. First try shocking it loose by lightly tapping on it with the end of a steel rod. Hopefully you can get a small needle nose vise grip to grab what little stump is left to ease it out.

You do run the risk of making a bad situation worse by trying to quick fix it. If it were my car, I would pull the motor, take my time, and be careful. You can fix this yourself without disassembling the motor.

Drimmel tool whats remaining to get as flat a surface as you can. Soak in PB Blaster for a day. REALLY soak it. Carb cleaner to clean the top. JB Weld a hex head bolt upside down to the sensor. Vice grips on the bolt to unscrew.

Hope this helps.

Tough luck, you may want to think along the lines of the whole picture, "what do I do if I get the piece out and all the threads are damaged or strip clean?" you can make threads, weld and re-tap,helicoil ect.. but anything you make them with may affect the transfer of heat to the CHT thus affect your engine warm up and maybe overall runing..

Maybe and not trying to be ass, but maybe it would just be easier overall to pull the head and take it to a machinist whom may be able to save and at least could re-make>>

Don't crack you head..

just a tip, you can pull the head without pulling the whole engine out if you drop it about 6 inches or so leave one tranny mount bolt on semi loose,
push the engine over to the side of the good head and there will be just enough room to pull problem head off, I have done it when an exhaust stud broke off with all the threads and a small chunk of my cylinder head too.. kind of surgical but saves a complete dislodgeing of engine .. just a thought..

I am going to drop the motor so I can see what I am up against. I'll try a reverse drill and square ezout. If it does not look promising, I'll have to pull the head. All fo a $15 part! Royal PITA!!!

Drop the engine and spray that sucker again.

The good news is sometimes breaking the head off relieves tension on the threads making it easier to spin the broken stub.

You might try placing a spring punch at the edge of the broken part, push down at an angle and use the impact to try to spin the stub out. Keep the punch point inboard of the threads and away from the center of the stub.

Sometimes a really small chisel applied to the same place with a small hammer works too.

Don't use epoxy to rebuild threads. Use a metal insert. Epoxy is not as good a thermal and electrical conductor as metal, and might screw up the sensor's readings.

no epoxy..

just thinking outside of the box
this may not be a good idea...

but both banks have the hole drilled.
I wonder how much difference in temp the other bank runs
I wonder if you could screw a sensor into the drivers side head, and then run an extension wire to the factory loom?

certainly easier than pulling the motor

Both banks are not drilled Brant. There are lefts and rights. If your 4 had both, someone had replaced a head. It also does matter, as the 3/4 bank gets hotter.

oop...
ok.
makes sense

JB Weld? You've GOT to be kidding, or you're an advertisers dream sucker. Sorry if I seem a bit harsh, but reality HAS to be inserted here by SOMEBODY.

The Cap'n

Pulled the motor and sprayed again. Tried a reverse drill bit, no go. Tried a #2 spiral easy out with a Roybi impact screw gun. Tried it by hand with a tap wrench. I did not want to apply too much torque and break off the asy out. Still won't budge. Sprayed some PB Blaster and will let it set over night. Try again tomorrow. Might try applying some heat with a MAP torch. Wish me luck.

heat is always your friend with stuck bolts...
or at least she is mine

OK he asked for Ideas. Since the sensor is already screwed, why not attach something to the sensor that he can get some leverage on...like a bolt 'welded' to the old sensor turned with vice grips? Drill into...Ezouts...why not just take a chisel and smash it down into the motor and then vacuum the remains out. It's an IDEA Capt'n. If all else fails down to pulling the heads, why not give it a shout. And this was posted long before he pulled the motor and other stuff. Hay, he did use the PB Blaster part. Gimme some credit here.

You can drill and retap the threads. It's 10 mm x 1.00. Enco has the tap for $7.

Thanks for all the replys. Still no luck getting it out. Looks like re drill and tap or helicoil?????

This is what I did on my engine. I guess my engine was rebuilt with 2 right side heads.

I don't think the temp difference between 1/2 or 3/4 will make much difference as the idea is to sense the relative temperature of the engine to adjust the width of the injector pulses as the engine is warming up and running warm.

To repair the broken side, it would seem that a dremel tool with a nice sharp grinding bit could take off the threads. You would only need to cut through the threads on one side & most of the bottom then chisel the rest out.

Drilled it out and retaped the hole, but the threads were shot. Think, think, think. I had an aluminum 1/4 pipe thread fitting. I drilled and taped the center to fit the 10mm sensor. Then cut the pipe thread fitting to the length of the sensor. Drilled the head and taped for 1/4 pipe thread. Screwed everything in, problem solved. I hope I don't have to replace it for another 35 years! Thanks for all the posts.

Good job! I am always amazed at the innovative ideas that come out on this forum! Let us know if all turns out OK and it runs OK.
Tom