Reference and speed sensors

[kqw]

I recently replaced my CHT and noticed that the rubber insulation shielding aroung the speed and reference sensors flacked off.

Is this going to cause a problem?????

[ChrisBennet]

Yep.
The failures I've seen of these sensors may actually be a failure of the wire. Those wires sit right over the exhaust and the insulation eventually fails. At least that's what happens here in the northeast. Maybe they would work fine in someplace totally dry. The ones I've seen fail often have heat related symptoms i.e. worked until the motor got hot.
Replacing the original sensors now is much cheaper than getting the car towed or paying for diagnostic time.
-Chris

[kqw]

Thanks Chris....

Can I re-insulate those wires or must I replace the sensors? If replacement is necessary, I am not sure on the correct spacing needed to put the new sensors in.

[Rot 911]

Right off the top of my head I believe the spacing is .08mm, but I would have to double check.

[ChrisBennet]

Oooh, soo close Kurt! If the wind hadn't blown the decimal out of place you would have been right on. (0.8mm)

If the gods have smiled on you, the sensors will slide out of the bracket and you can put the new ones in. (Yeah right!) The adjustment is accomplished with the bracket so if the bracket isn't moved you'll be all set. Otherwise you need to stick/glue an .8mm washer to the end of the old sensor and adjust the bracket that way.
-Chris

[kqw]

If I am correct, the only sensor that needs to be positioned is the speed sensor as the reference sensor will automatically be positioned correctly if the spped sensor is fitted correctly. (right??????)

[ChrisBennet]

Originally posted by kqw
If I am correct, the only sensor that needs to be positioned is the speed sensor as the reference sensor will automatically be positioned correctly if the spped sensor is fitted correctly. (right??????)

From memory (any we all know how bad mine is), it's the lower of the two sensor that you set the gap on. I can't remember if that is the speed or reference sensor.
-Chris

[kqw]

Thanks

[KTL]

The wire sheathing on our midwest cars suffers the same fate as Chris' NE sheathing. Cooked by the exhaust.

The sensors i've replaced have all needed to be driven out of the bracket. And get busted up pretty good doing so. Just don't damage the bracket. Good luck getting them out without damaging one or the other. Hopefully the one that gets damaged is the one with the bad wiring? But, it'd be wise to replace both since the wire sheathing is most likely bad on both of them. They are unfortunately not cheap. $120 each.

[kqw]

Thanks Kevin...

Are both the Ref. and Speed sensor the same part number? I'm having a heck of a issue locating a parts source for these sensors...

[goat]

Darren at pelican parts faxed me a copy of the specs for these a while ago. I do believe that they had the same number. don't have the paper with me. Maybe he could do the same for you if you give him a call.
Pricey little wires too.

[kqw]

Thanks Tim.....

[jc]

I replaced mine recently so here's a tip:

Before you remove the old one, tie a string to the end of it. That way when you pull it out you can use the string to navigate the new one in place through the hole behind the engine.

Cheers
jc

[kqw]

Gotcha...jc

Thanks

[Jeff Alton]

Chris is right. It is the lower one that you set the gap on (.8mm) and then the upper one is set automatically.

Cheers, Jeff

[Lorenfb]

The gap on the sensors is not critcal, as long as they are NOT forced too close
to the flywheel. As long as the bracket has not been altered/damaged, the gap
should be O.K. If the boots are cracked or damaged, you can seal and hold the
boots together (and seal out moisture) by filling the boots with RTV silicone.

The key for the sensors is the voltage generated at cranking:

1. reference - > 80-100 millivolts A.C.
2. speed - > 1.00 volts A.C.

[rob justice]

When re-fitting the sensors into the alloy bracket - is it worthwhile smearing anti-seize onto the outside of the sensor? I had one seize and fall to bits when I tried to remove it. Or would the sensor not work correctly if coated?

[ChrisBennet]

Originally posted by rob justice
When re-fitting the sensors into the alloy bracket - is it worthwhile smearing anti-seize onto the outside of the sensor? I had one seize and fall to bits when I tried to remove it. Or would the sensor not work correctly if coated?

I antisieze mine but I haven't had occasion to remove them afterwards so I don't know if it makes a difference. Antisieze does not effect operation.
On the subject of grease/antisieze and it's effect on electrical contacts; I have not found it to hurt anything. On the contrary, it keeps oxygen away from the contacts and slows down corrosion.
-Chris

[rob justice]

Thats cool because the one sensor that was able to be withdrawn was one hell of a state when removed from the bracket.
Mainly because of the cold wet climate over here - if its not coated - its seized.

[KTL]

How about using dielectric grease? Seems that it'd serve the same purpose as antiseize Or would the dielectric grease not last as long?

goat is right. Part #'s are the same for the senders.