Crankshaft position sensor bolts

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CheeseHelmet

Member

• May 3, 2010

• #1

I noticed that I couldn't thread the bolts by hand so I used a wrench to put the first one in and about 2/3 of the way in the head snapped off. I wasn't even applying much torque... The bolts are as old as the car so I suspect that's why it was so weak.

The service manual says that those bolts get tightened to less than 10 foot pounds. I'm assuming there's something special about the threads on the engine-side that prevents them from falling out due to vibration. Could this be why they're hard to tighten?

That being said, I have to remove the broken bolt so I went and purchased two types of extractors. I got the traditional reverse-thread drill bit and a set of "Grab-IT" bits. Any idea which one will work better?

 

M

MaxPower

Member

:

'01 Pro ES

• May 3, 2010

• #2

Those bolts should be easy to put in... I'm surprised one snapped on you. The shop manual doesn't show any threadlocker or other material should be used on the bolt. Is it possible you cross-threaded? Maybe the threads were dirty?

 

C

CheeseHelmet

Member

• May 3, 2010

• #3

MaxPower said:

Is it possible you cross-threaded? Maybe the threads were dirty?

Click to expand...

The threads on both bolts were perfect, the heads were pretty rusty but still usable. I think you might be right about the cross-threading, it was the end of the day and I was tired... It just surprises me how little torque was needed to break it.

 

C

CheeseHelmet

Member

• May 4, 2010

• #4

I tried the Grab-IT and the screw extractor and both failed to remove the bolt. The Grab-IT just chewed up the soft bolt metal and the screw extractor broke off inside the bolt. At this point I gave up and re-installed the sensor.

The sensor itself has a little plastic post on the back of it which makes the sensor snap onto the engine. I think that the post in combination with the bolt that's still there should be enough to keep it in place. Also, the bolt that snapped off sticks out by 3-4mm so it'll keep the sensor from moving from side to side if the plastic post were to ever break.

I was thinking of using some glue to really hold the bottom of the sensor in place, is it a bad idea to leave it like that?

 

P

P-Funk!

:

Lancer Ralliart Sportback

• May 4, 2010

• #5

I would do more to secure it. If it fails - the engine stops running (safety and PITA issue). I agree with gluing or RTV'ing it (be careful not to affect its functionality).

 

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MaxPower

Member

:

'01 Pro ES

• May 4, 2010

• #6

Those lousy bolt extractors break when even mild torque is needed. I guess in retrospect the best route would have been to drill the bolt out and install a helicoil.

I don't know if you can still install a helicoil--those bolt extractors are made of a pretty tough metal that's hard to drill out, but it might still be possible. You might want to consult a mechanic or machine shop and find out if they'd be willing to do it and for how much.

 

C

CheeseHelmet

Member

• May 4, 2010

• #7

Well, I epoxied it. Hopefully I'm not left stranded somewhere one day...

I think it'll be ok, it was very solid (you couldn't move it at all) before I put the glue. I'll take a look at it periodically and if I have the balls to do it one day, I'll drill and tap it. From what I've read, you can drill through a screw extractor using a really hard bit.

EDIT: From now on I'm not even going to try using screw extractors, I'm just going to drill and tap (or use a self-tapping bolt).

 

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wildo

Member

:

Mazda Protege5

• May 5, 2010

• #8

If the bolt is sticking out 3-4mm, then you could take a hacksaw or sawzall and cut it off flush with the engine block. This might remove the busted extractor. Then you could drill it out as usual and install a helicoil...

 

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metallargy

Member

• May 6, 2010

• #9

Have you tried vice grips?
I'd remove the crank pulley to keep from messing up the sensor teeth while using them.

Judging by the looks of your oilpan, the hole was probably oxidized/corroded.

I've never had luck with screw extractors, but I've had luck with reverse drill bits. Should be able to pick those up locally if vicegrips won't grab.

 

C

CheeseHelmet

Member

• May 6, 2010

• #10

metallargy said:

Have you tried vice grips?
I'd remove the crank pulley to keep from messing up the sensor teeth while using them.

Judging by the looks of your oilpan, the hole was probably oxidized/corroded.

I've never had luck with screw extractors, but I've had luck with reverse drill bits. Should be able to pick those up locally if vicegrips won't grab.

Click to expand...

Vicegrips were the first thing I tried. There isn't enough room to get a good grip and still be able to turn it. Maybe if I removed the crankshaft pulley it there would be more room but that's a lot of work...

I've driven 120KM so far and haven't had any problems, I'll check it from time to time but if it works this way I'm not going to risk making it worse.