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[omega2018]

I agree original is usually better than pattern in lots of things but from an enginnering point of view i myself would like to know what the difference is. When a crank sensor fails.be it original or cheap one what actually stops happening ?.does something go open circiut or what ? . Anyone any ideas.

when i remove mine, after satisfying myself that the new one fixes the problem i'll dismantle it and have a look..  with a hammer

i wonder if the proximity to the oil filter and oof members' pension for frequent oil changes may be part of the problem. my current sensor has witnessed 4 oil changes since installation.

[Doctor Gollum]

Penchant, not pension

Frequently changing the oil is better for the life expectancy of the engine than leaving it for 20K miles

[cam.in.head]

I was under the impression that  the crank sensors were hall effect too because of the 3 wire spec.if thats the case then it would have slighly more chance. Of faillingrather than a straight pick up coil but i am still curios as to what actually gives up.if as some have said its the cable then carefull positioning or heatproofing may be the answer. There must be something that gm sensors get right that no other aftermarket sensor can but id like to know what or why. As an engineer by trade im not just happy with "oem is best" i always want to know why one thing is better than another and why?same goes for all the pattern parts vs original

[Kevin Wood]

Last time I had one fail, it had gone open circuit.

It's a coil of fine wire which is terminated into a screened cable and the whole assembly is then potted and screwed into the side of an engine block where the front face is then splashed with oil at up to 120 degrees C.

Being potted means that it's very difficult to do a "post mortem". My guess would be that the thermal cycling in use eventually causes the fine wire ends of the coils to fatigue where the housing in which they are potted expands and contracts slightly with each engine heating cycle. This is backed up by the fact that failure is often temperature related in that the engine will stall at high temperature only to restart normally once cold.

As to why it must be genuine - most probably GM have tighter specifications on the quality of the part if it is manufactured for them. Their manufacturers are probably now no longer subject to any exclusivity on making the part, so they can sell them in the aftermarket, but they could choose to use cheaper materials that wouldn't pass GM's acceptance criteria. They may even choose to sell batches of parts that were rejected by GM to the aftermarket. For some parts this wouldn't matter, but for a part that's already in a pretty hostile environment and prone to failure it's the difference between it lasting a week weeks or many years. 

We can speculate on the reasons, but the fact of the matter is that, in the decade that we've been here, a pattern has emerged that only genuine crank sensors have been worth bothering with.

[TheBoy]

the current sensor is a genuine Delphi sensor.  Delphi automotive is a well known brand, one of the world's largest automotive parts manufacturers.  it was set up by general motors (vauxhall) in 1994.  a lot of mig original parts are Delphi.  my brake pads are Delphi.  so Delphi are a 'decent' brand.

This is why we constantly (from crank sensors), genuine GM part from a real Vauxhall dealer. Nothing else.


For the record, Delphi aftermarket parts are mostly considered pretty poor, on par with all other very low cost pattern parts, and probably from the same Chinese factory as acmepartsltd get theirs

But low cost pattern parts have a place in life. Just not on Omega V6 crank sensors. (Or brakes, but that's off topic)

[TheBoy]

i wonder if the proximity to the oil filter and oof members' pension for frequent oil changes may be part of the problem. my current sensor has witnessed 4 oil changes since installation.

I have a theory about this, but my own personal evidence isn't broad enough to even begin to be conclusive...


...but I really do wonder why GM re-engineered the oil filter from the crap VOF93 spin on to a paper element type for the V6 engines in 1999. And only the V6 engines. With the sensor/wire right beside it.

[omega2018]

I currently have 3 crank sensors, one new unbranded (my emergency spare), one dodgy looking unbranded used one and the one in place, a Delphi. I'll test the Delphi on removal.  here are the results for the other two.   

on my decent multimeter:

pin 1 to 2 (left to right, looking at tapered catch) 0.939KOhm on used one, 0.965KOhm on new one

nothing between pin 3 and any other pin. 

my megger tester shows them fully closed circuit pin 1 to 2 and fully open circuit on the other permutations.

incidentally these crank sensors definitely have permanent magnets in them, powerful enough to hold their own weight. so i assume that means they are not hall effect sensors?

[Kevin Wood]

Yes, it's a VRS, not a hall sensor. 

[omega2018]

this web page is useful http://www.aa1car.com/library/crank_sensors.htm eg:

"Magnetic sensors can be checked by unplugging the electrical connector and checking resistance between the appropriate terminals. On a GM 2.3L Quad 4, for example, the sensor should read between 500 and 900 ohms"

"A good magnetic crank position sensor should produce an alternating current when the engine is cranked, so a voltage output check while cranking is another test that can be performed. With the sensor connected, read the output voltage across the appropriate terminals while cranking the engine. If you see at least 20 mV on the AC scale, the sensor is good, meaning the fault is probably in the module, coil, wiring or computer."

and

" The third type of crankshaft position sensor is a magnetic pickup that reads slots machined in a "reluctor" ring in the center of the crankshaft, on the harmonic balancer or flywheel. This setup is used on GM engines with the Direct Ignition Systems (DIS) on the 2.0L, 2.5L and 2.8L engines, and the Integrated Distributorless Ignition (IDI) on the 2.3L Quad 4, and also many Ford, Chrysler and import engines.

On the GM applications, the crank reluctor ring has six equally spaced slots 60 degrees apart. A seventh slot is spaced 10 degrees from one of the others so the crank sensor will generate an extra "sync-pulse" every revolution. The PCM then uses the information to calculate proper ignition and injector timing. This type of sensor must be carefully positioned so the air gap is within .050 in. of the crankshaft reluctor ring."

also from wikipedia

"One detail of some designs is the "three wire" inductive crank sensor whereby the third wire is actually just a co-axial shield around the two main sensor wires to prevent them from picking up stray electrical pulses from elsewhere in the vehicle engine bay."

[omega2018]

here are the readings for the existing delphi sensor

590 Ohm
1V AC when starter turning, pins 1 and 2
0.14V AC when starter turning pins 2 and 3

[omega2018]

new sensor arrived today no brand on it but "made in italy" on the plug and unlike my spare it does have some markings on the sensor head - >PA66- GF30< and 0284 08D.  also a batch number sticker 65407.  Box says CS1242 location 3G-D5-S1 batch no G065407

reads 875 Ohms

i will fit it and report back (keeping both spares in the boot with the relevant tools)

[Doctor Gollum]

Don't know why you bothered to ask for advice which you had every intention of ignoring...

[omega2018]

Don't know why you bothered to ask for advice which you had every intention of ignoring...

no i cannot fit a bosch sensor because I only have my spare cheapo ones.  I have ordered a genuine bosch one and will fit it when it arrives.  incidentally the only advice you have given here is how easy it is to change the plugs on a v6 (which it isn't ) and that a v6 will run on 3 cylinders which is irrelevant

[TheBoy]

The recommendation for V6 crank sensors is to buy a genuine GM one from a bricks-and-mortar dealer. Not Bosch. Not Siemens. Not Delphi or other similar tat.


This recommendation comes from huge amounts of experience from helping others who have also tried all the other routes, thing they knew better.

[omega2018]

the one you get from a gm dealer is bosch isn't it?  Doesn't it have the word 'bosch' on it? apart from the square plug older ones which are Siemens?