'95 LeSabre Dies Without Warning

[delhsn]

I went down to the parts store last night and bought a Haynes manual for the car to see how difficult it would be to replace the crank sensor ... it says you have to remove the vibration damper, and that you need a special tool to realign the sensor when you put it back on. I'm reasonably savvy but this looks like it might be something I don't want to tackle on my own ... how difficult did you find this to do? What special tools might I need?

It indicates that removing the vibration damper involves taking off the right front wheel and fender splash guard, and that it's a two-man job ... then it cautions about realigning the sensor so it doesn't contact the vanes on the damper, which is what worries me ...

I see now why you tried other things first ... this is quite a thing to undertake on the "chance" that it is going to fix the problem. Yet, based on your experience, it seems at least a 50/50 ...

Del

[timrice]

I didn't do the work myself on this recent problem I had with my '95. (I did it on my older '89 a couple years ago.)

I don't recall needing any special tools. I do remember the worst part was trying to get the pulley off to get at the sensor. Two words: "cheater bar." I'm guessing the key to "aligning" the sensor is simply to make sure the air gap between sensor and vanes is correct. I'm pretty sure I "eyeballed" mine. Perhaps you could use a gauge (the shim style) for gapping plugs to check the gap on the original sensor before putting the new one on. But being such a shade tree mechanic (and not a very good one at that), I would defer on this issue to the more knowledgeable folks on the forum.

On my '95, the crank sensor replacement was $150 total, parts and labor. I felt like it was worth it at that point. I was at a frustration point where I just didn't want to work on the car for a while--I needed a break from it, so I let the boys at the shop take their third crack at it. Third time was the charm. I will say that if the ECM had done its job and set a *crank* code in the first place, it would have been fairly likely that I'd have tried doing it myself at that point.

If you have access to a portable oscilloscope (not likely), you could monitor the outputs of the crank sensor while cranking or driving. Essentially that's what my shop did to catch it in the act. If your car dies or won't start and the outputs of the crank sensor are doing what they should, the problem lies elsewhere.

I was faced with the choice of replacing the ECM or the crank sensor there at the end. I chose ECM (wrongly) for several reasons:

a) It was by comparison an easier replacement
(as you point out, the crank sensor poses a
bit more of a challenge)
b) More people I'd talked to thought it was the
ECM that would ultimately be at fault. And
those thoughts weren't without some merit.
c) My shop had been unable to catch the crank
sensor malfunctioning for a perod of two weeks
while they had my car the second of the three
times.

If I were you, I would go ahead and go for the crank sensor replacement. If it still doesn't work, you're only out your time and the cost of the sensor, and look at it this way--your car is 10 years old now, and it may still have the original sensor on it. If you put a new one on, it may be several more years before you'll have an inevitable crank sensor failure. Let's face it--these things are made of plastic, and they're in a very abusive environment. The thermal cycling alone is extreme.

Best of luck, and keep us posted on your progress.

[rustbucket]

I replaced the crank sensor on my '87. I did not have to take off the vibration damper. You may want to turn the crankshaft until the vanes on the back of the damper are not in the slot of the crank sensor. There are two bolts holding the sensor bracket to the main block.
If you have to take off the damper, visegrip the flywheel in the little hole at the bottom of the engine and get out your big wrenches, but I dont know what you would use the second man for. As far as aligning, I eyeballed mine so the vanes went through the middle of the gap. That may have been a mistake, because the new sensor caused it to "miss", and I put the old one back on. I would advise to set the gap the same as the old one.

[delhsn]

It rained all weekend so I didn't do anything with the crank sensor ... I did talk to a shade-tree mechanic friend of mine about having him do the replacement, and he said (in his opinion) there's no way it's the crank sensor. He said in his experience this is most likely caused by the MAF (Mass Air Flow) Sensor. I don't see anyone else here talking about that ... is this something anyone else tried? It's easy to get to, I may just replace it and see. Oh, by the way this morning my car ran like brand new, didn't falter once ... perhaps it likes the cool humid environment of Tampa after three days of rain ...

[rustbucket]

I dont think the crank sensor could cause all the lights to flash (especially temperature)

[delhsn]

I've been paying a little more attention to that, and I think that what is really happening is ... the lights (temp / oil) just flash when the car is trying to stall ... the same as when the key is on but the car is not running. If it does stall, they stay lit, otherwise they just flash for a second at the same time as the speedometer is jumping. The service engine soon and anti-lock brakes lights are staying on most of the time now. Service engine probably means a code has been set, and anti-lock brakes may be totally unrelated.

[rustbucket]

I guess if the crank sensor said the engine was not turning, the computer may turn on the lights the same way it does when you first turn on the key. and then before it really dies, the sensor starts working again and the lights go out..mmm..?

[timrice]

delhsn, my speedometer juked and my dash lights would wig out just like you're describing. I would agree w/rustbucket: the ECM/PCM is probably doing its bulb check. (Why your ABS light stays on is not clear--mine didn't.)

I would read the codes out first. If you don't have a reader, most of the parts houses will read 'em out for you. If you have a *cam* sensor code, I would sure replace the *crank* sensor at that point. I have it from several sources that a bad cam sensor circuit won't kill a running engine. I know firsthand that a bad crank sensor will.

I would not be in a hurry to replace the MAF sensor unless you're pretty certain that's it. Those are fairly expensive. Seems like when I needed one for my '90 a couple years ago, it was $200 to $400 depending on where you got it. In the case of my '90, to confirm I really needed one I swapped the one off my '89 with it and the problem followed the sensor, so then I went to the salvage yard. I plopped down $50 and got a whole 3800 throttle body with all the sensors and controls attached. I'm betting if you had the factory manuals, you could look up the proper voltage output range for the MAF, and then just make a simple check with a multimeter, too.

[3echo9]

He all....great thread. I've been trying to get at my CPS to replace it but I'm having a difficult time removing the Crankshaft pulley bolt. It's a 91 Lesabre or maybe a 92' per the guy who put a new windshield in it...anyway...I tried a 250 lb air wrench and a breaker bar. Part of the problem is getting the pulley to keep from turning. I put a big screwdriver in the power steering pulley to jam it from moving but it doesn't keep totally still. Any ideas...bigger hammer with more torque? I tried a 250lb'er with a 2 gal pancake compressor....I know...pretty small...I use it more for shooting nails and pumping up the kids bicycle tires. The shop quoted $200 plus tax for the job. The part was $30-35 bucks....and I'm cheap.

Thanks for the help.

[delhsn]

I bought the Haynes manual for $17 at Discount auto, I believe it recommends putting a screwdriver into a spot on the flywheel to keep it from turning, will look tonight when I get home. Did you have to take the front wheel and wheel shroud off to get to it? The more I read the more I think the CPS is my trouble too, I just can't see it being the MAF ...

[3echo9]

My manual didn't mention anything about how to keep the pulley from moving. I did not have to remove the wheel. Just a splash shield. It had a few plastic retainers that pop out with a screwdriver. You can buy replacements at the local auto parts company.

I don't buy off on the MAF sensor either.

[rustbucket]

!!! Dont try clamping or stopping the serpentine belt from moving while trying to turn the crank bolt!!! It will ruin the damper. I did it that way when replacing my timing chain and after I got all done, I had this terrible clanging, ran fine, but made a racket while at a stop. Turned out the damper internals had shifted enough that the support parts were hitting each other. $218 for a new one. Try vise grips on the flywheel. You might have to take off a little plastic cover to get to the flywheel. I used a 250 ft lb torke wrench with a pipe extender. I actually couldnt get it by going out through the wheel well, I was sitting on the windshield. with no extenders on the socket.

[delhsn]

The instructions for removing the vibration damper state: (paraphrased)

1. Disconnect the neg. batt. cable (caution re: Delcolock stereo ... )
2. Loosen lug nuts on rt. frt. wheel
3. Raise vehicle / support on jack stands
4. Remove rt. frt. wheel
5. Remove rt. ft. fender inner splash shield
6. Remove drivebelt
7. Remove the lower bell housing cover plate and position a large screwdriver in the ring gear teeth (see illustration) to keep the crankshaft from turning while an assistant removes the crankshaft balancer bolt. The bolt is normally quite tight, so use a large breaker bar and a six-point socket.
8. The damper should pull off the crankshaft by hand. Leave the woordruff key in place in the end of the crankshaft.

That gets the vibration damper out of the way, then its a matter of replacing the CPS, being careful to align it properly so it doesn't touch the vanes on the vibration damper when its reinstalled.

[timrice]

Ditto what delhsn says. Under the "Vibration Dampener Removal" section in my Haynes manual, it says: "Remove the lower bellhousing cover plate and hold the crankshaft with GM tool J37096 or equivalent, or position a large screwdriver in the ring gear teeth to keep the crankshaft from turning while an assistant removes the crankshaft balancer bolt. The bolt is normally quite tight, so use a large breaker bar and a six-point socket."

(This may be where the "two-man" job comes in, as was questioned in post #68.)

[3echo9]

Thanks that did the job. I got the bolt off but the dampner is being stubborn. I've tried to gently knock it free with a hammer and extension from behind but no luck. I'll give another shot later today and post the results...but if anyone has any suggestions I'm all ears.