1995 SR 3.5 DOHC Crank Sensor Issues

[Bottomfeeder]

I have had replace the crank sensor 3 times in a matter of months. It appears as though i need another. What is my next step to figure out why I keep having to replace this sensor? What is killing these sensors?

There was No visible damage to the 1st 2 I replaced.

When we took the engine apart to to extract the bolt, the original sensor was in 2 pieces. So i picked up a new one at Oreilly's. Fixed the crank bolt problem successfully. Engine fired right up. Installed remaining hoses, radiator, alternator and compressor. Engine won't start. Took everything apart again. figured it was a bad sensor. Got a new one from Oreilly's. Went through the whole process again. Engine fired right up. Drove it for a day and it failed again. Now I'm angry... Ordered a genuine Mitsu sensor. Whole process again. Drove it for about 3 weeks. Its started to stutter at highway speeds. If I drove under 40mph it was fine. About 3 weeks later the stuttering got worse. Replaced the fuel pump. Drove down the road and it died again. And here I am

And, when it was running, it ran real nice. Put a new alternator and starter in there while it was disassembled. The crank bolt broke from the wrench used to remove it. Not while the engine was running.

 

[PA_JERO]

Pins in the crank sprocket may not be holding the blade the crank sensor uses to sense the revolution of the crank. Blade could also be bent slightly. Check the spacing in the fsm to make sure there is nothing missing from that set up. Genuine oem part again after you check into all of the nonsense behind the crank sprocket. OtherWise check for oil, water, or something else getting on it, double check wire routing as well.

 

[Bottomfeeder]

Thanks for the info

I will check it. So far no oil and such

 

[Pdivizzle0112]

Can you replace the crank sensor without tearing too much down?

 

[nwoods]

Can you replace the crank sensor without tearing too much down?

No. It's a PIA.
It's basically a full timing belt job, including removing the radiator if you like to have room to work in.

 

[Bottomfeeder]

No. It's a PIA.
It's basically a full timing belt job, including removing the radiator if you like to have room to work in.

The whole front of the motor has to come off. I can't find the info in the FSM for spacing. I have been all up in the pages of the FSM. Probably right in front of my eyes.

 

[Pdivizzle0112]

Great, should've replaced mine when I did the tbelt. Thanks fellas

 

[JohnnyBfromPeoria]

Great, should've replaced mine when I did the tbelt. Thanks fellas

Easy there. Virtually no one replaces this part or the cam sensor when doing a timing belt job, as they are very durable. Usually, the wires leading into the sensor would be the only concern. BottomFeeler's was broken in half, or he likely would have just left the old one in there. Mine's stock and I bet most everyone else's is too.

John B.

 

[PA_JERO]

Mine is stock.

 

[Salonika]

Mine has been replaced once. I did it without touching any timing components if I recall correctly. I don't remember if I removed the radiator, but I do remember being surprised that I pulled off the job without following the whole FSM procedure. Sort of like the starter job.......FSM says you have to remove trans cooler lines to get it out, which you don't really need to do, just be patient and creative.

 

[Bottomfeeder]

I went through the FSM again today. Can't find any info on the spacing for the crank sensor.

 

[nwoods]

Not sure what you mean by spacing. The crank sensor attaches to the block with two screws snugged up tight. The timing plate attaches to the back of the crank gear and it can only go one way, fitting over a pin or stud if I recall correctly. The crank gear also only goes one way, with a slot and key setting it in place. On the front of the crank gear is a locator pin that fits the crank pulley.

 

[Bottomfeeder]

Pins in the crank sprocket may not be holding the blade the crank sensor uses to sense the revolution of the crank. Blade could also be bent slightly. Check the spacing in the fsm to make sure there is nothing missing from that set up. Genuine oem part again after you check into all of the nonsense behind the crank sprocket. OtherWise check for oil, water, or something else getting on it, double check wire routing as well.

This is what I was referring to

 

[nwoods]

Here is a photo of the crank gear and timing plate and sensor properly lined up and installed

Here is something that came up on me. As you can see in the photo above, the washers I used to keep the crank bolt from threading all the way down actually were too big and pushed the locator pin into the crank gear. DOH! I had to buy a new crank gear, and I went ahead and bought a new timing plate as well. Turns out, the OLD timing plate was the WRONG one and was causing misfires and general engine woes and I was never able to figure out why. When I got the new ones in, I stacked them up, and wow, the new one was about 15 degrees different from the old one. Turns out, the old one was snagged off a 1997 DOHC 3.5L, and was just different enough to be major source of frustration.

Also, if those little pins in the back of the crank gear shear off, and the timing plate stops turning at the right rate and alignment, this can happen

 

[Bottomfeeder]

New parts ordered and on the way. Sensor, spacer and timing plate. 5th time to disassemble the motor.