L29 454---Replace Crank Sensor

[RedBurb]

Greetings ---I've ordered a new crank sensor from Rock Auto (GM Genuine Part) to replace the original sensor from 180K miles ago ('97 K2500). Are there any "watchouts" I should be aware of before tackling this swap out? For instance does the engine have to be set to TDC before beginning the replacement? Also, is there a chance the new sensor will have to be "taught/calibrated" after replacing? Is a special scanner tool required to properly complete the install. Etc.

Bottomline ---Is this is a "plug and play" or a "fight and pray" job?

All feedback welcome. Thanks

 

[Supercharged111]

You really should do a crank relearn with the new sensor. I think that's it though. What led you to replace the sensor?

 

[454cid]

Take a look to see if the old sensor was rubbing and make sure the new one doesn't. I think you can shim them, but I didnt have to deal with that. I just cleaned the original up and reinstalled it. They are sealed with an oring and I probably greased it with silicone dielectric grease.

 

[RedBurb]

Can the "crank relearn" procedure be performed without a scanner? Or is a scanner a must?

I've decided to change out the crank sensor since it's practically the ONLY remaining engine sensor that I haven't changed during the last 12-14 months. It was also routinely drenched with oil due to the timing cover leak I'm currently fixing. Proactively changing these old electronic components should pay off in terms of long term reliability once/if they survive the "infant mortaility" stage.

 

[RedBurb]

Take a look to see if the old sensor was rubbing and make sure the new one doesn't. I think you can shim them, but I didnt have to deal with that. I just cleaned the original up and reinstalled it. They are sealed with an oring and I probably greased it with silicone dielectric grease.

Did you recall whether you had to perform a "Crank Relearn" procedure after you reinstalled the original?

 

[454cid]

No, I didn't do a relearn.

I would not change it just becasue you haven't done so. Mine was all greasy, and probably is again. It's got almost 300K miles on it, and I'm not going to replace a part that's working fine.

 

[JeremyNH]

You won't have to do a relearn. The ECM won't even be aware that the sensor has changed. The crank sensor is just a magnetic switch that senses when a lobe of the reluctor wheel is above it (magnetic field high, switch on) or not (magnetic field low, switch off). Since it's an on or off signal there isn't anything to calibrate in the ECM. It being covered in oil won't make any difference to its' operation only the gap distance between the sensor head and the reluctor lobe (hence the shims). A leaking cover has nothing to do with how much oil gets to the sensor though. The timing cover seals aren't under any static oil pressure, just the dynamic force of oil being flung off the timing chain, sprockets, and the reluctor wheel. Whether the seals capture the oil or not won't affect how much showers the sensor. I presume you intend to replace it when you replace the timing cover. As others have mentioned though it isn't a fault prone part so your call as to justification. Keep the old one though since you know it's working and if the new fails young you can swap it in. Only takes five minutes.

 

[thegawd]

I have a code for the crank sensor, I cant remember off the top of my head what it is but it doesn't seem to affect anything. fuel mileage is the same. this is in my 97 k1500 Burb with a 350.

I guess I need to find this sensor and trace the wires. I assume it's a wiring issue as it does not always set.

I thought this was the cam sensor in distributor and put a new sensor in there before I realized I was way off.

I dont know, sometimes I dont look anything up.... That's dumb.... I Know... I realize now that the crank sensor is behind/near the harmonic balancer.

is it accessible without removing anything?

is there a known rub point that may destroy wires?

could hot exhaust coming from a completly blown out donut gasket somehow blow on these wires and melt them?

Ya I know..... go find it and fix it but I dont have the parts to do so and just looking into some insite.

the truck runs perfectly now that I replaced the donut gaskets and fixed the exhaust leak. other than getting the crank sensor codes mileage is still good.

thanks guys.

 

[JeremyNH]

I have a code for the crank sensor, I cant remember off the top of my head what it is but it doesn't seem to affect anything. fuel mileage is the same. this is in my 97 k1500 Burb with a 350.

I guess I need to find this sensor and trace the wires. I assume it's a wiring issue as it does not always set.

I thought this was the cam sensor in distributor and put a new sensor in there before I realized I was way off.

I dont know, sometimes I dont look anything up.... That's dumb.... I Know... I realize now that the crank sensor is behind/near the harmonic balancer.

is it accessible without removing anything?

is there a known rub point that may destroy wires?

could hot exhaust coming from a completly blown out donut gasket somehow blow on these wires and melt them?

Ya I know..... go find it and fix it but I dont have the parts to do so and just looking into some insite.

the truck runs perfectly now that I replaced the donut gaskets and fixed the exhaust leak. other than getting the crank sensor codes mileage is still good.

thanks guys.

It's replaceable without removing anything. It's held on by a single 8mm screw (not sure about the size, going from memory). The hold down bracket also supports a loom harness so you'll have to open it to get it off the loom and then transfer the harness to the new sensor bracket. The crank sensor is what tells the ECM when to fuel which cylinder and when to fire (all cylinders, the distributor sends the spark to the right one). The 4X reluctor tells the ECM when the cylinders are at TDC. The cam sensor sends a single pulse per two crank revolutions to tell the ECM when the #1 cylinder is on compression stroke so it knows when to start the fueling order (e.g. crank pulse tells ECM that #1 and #6 are at TDC and the cam pulse tells it that it is #1 on compression so #6 is on exhaust and every crank pulse after give it the next cylinder pair so next #8/#5 at TDC comp/exh yadayada) among other things. Point being that if the crank sensor isn't working your motor isn't working either. Whatever your problem it doesn't sound like it's crank sensor related directly.

 

[thegawd]

Well that's a great explanation man holy hell I think I understand it more.

well it is a crank sensor code and now that my wife is back home with the truck I will go have a look.

BRB

OOPS sorry now I'm even more of an idiot and confused. LOL Its a camshaft sensor P0340 so it's not even related to this post.

Sorry for wasting your time but thanks for the help! LOL

camshaft sensor is the one under the distributor, I replaced it already so I need to chase the wiring down.