: Mystery klanking sound.. over 200K N*



eldoradoin
01-11-13, 03:10 PM
Okay, here goes. My 95 Eldorado has a klanking sound coming from (possibly) the bottom end. I had a complete bottom end rebuild at 150K. It "klanks" along with the starter, and at idle speed (around 750 rpms). The engine sounds perfect at or above 900 rpms). Newer transmission, flexplate and torque converter. ( I checked them all, no play) My question.. what the hell is it? It sounds like someone banging two oil cans together (for those who remember oil cans). I thought the bottom end of the N* was bulletproof.

The only code I'm pulling is a P132 -knock sensor circutry. I don't think a bad knock sensor would even cause this noise.

Anyhow, any ideas? Would a bad belt tensioner make this noise? Belt driven accessories?


As always.. thanks for the input ahead of time.

Ranger
01-11-13, 03:56 PM
What do you mean by "klanks along with the starter"? Have you checked for a broken starter pinion return spring? Maybe the pinion is bouncing off the flywheel ring gear.

eldoradoin
01-11-13, 04:23 PM
Hey Ranger.. sorry, forgot to say that I replaced the starter too. That would be too easy, now wouldn't it? ;)

edit: Now, you have an idea of the "klanking" sound I'm talking about though. It would sound like the starter pinion stuck out and banging off the flex plate.

daveyhouse
01-11-13, 04:34 PM
possibly a hairline crack in flywheel? Borrowed a truck that had the noise you are describing last year. The flywheel had no play but we dropped the tranny anyway, and low and behold it had a crack near the mounting bolts. Replaced it and the sound was gone.

It only did it at an idle or certain unloading conditions, never during acceleration

Edit: Hopefully it IS your starter pinion.

eldoradoin
01-11-13, 07:57 PM
The flexplate was changed last summer. I'm wondering if anyone has shimmed their starter. I've used shims on other GM vehicle's starters, but they were the exterior type.

Ranger
01-11-13, 10:04 PM
Never heard of one needing to be shimmed.

Try this. Take it for a ride and make a hard right turn. If you hear that clanking, then I'd put money on the pinion returns spring. Centrifugal force would be throwing the pinion into the spinning flywheel ring gear. A hard left would slide it back away from the flywheel.

eldoradoin
01-12-13, 09:32 AM
I thought that it just had to be the starter pinion as well, but what are the chances of two of them having the same problem?

Ranger
01-12-13, 11:53 AM
Slim (unless the replacement was a cheap aftermarket AZ Don'tLast starter).

eldoradoin
01-13-13, 11:23 AM
It was a cheap aftermarket starter... 70 bucks on ebay. The sound didn't go away in the first start though. I'm wondering if those goofballs put my flexplate in wrong. I went for more than a year without this noise. I was really listening last night, and the starter might just be the problem.

Ranger
01-13-13, 12:51 PM
All bets are off. You're just gonna have to pull the manifold and have a look.

eldoradoin
01-13-13, 06:51 PM
It isn't like I haven't been in there before. ;) Thanks Ranger..

carnut
01-30-13, 10:40 PM
My money is on a cracked flexplate where it bolts to the crankshaft. Sometimes you can see a rust streak from the bolt on the flexplate face. The crack flexes and rust forms on the crack and streaks down from the bolt hole. The flex plate is a very tight fit on the crankshaft end. If not fully seated when replaced, it would flex too much and crack. Why was the flex plate replaced in the first place?

eldoradoin
01-30-13, 11:52 PM
My money is on a cracked flexplate where it bolts to the crankshaft. Sometimes you can see a rust streak from the bolt on the flexplate face. The crack flexes and rust forms on the crack and streaks down from the bolt hole. The flex plate is a very tight fit on the crankshaft end. If not fully seated when replaced, it would flex too much and crack. Why was the flex plate replaced in the first place?

The flexplate was switched out, after 214,000 miles. It centered out, so I don't think it's the problem. One question for all. How many portals are there to check the crank/flexplate. I'm thinking a wrench is in there. seriously.. :/

carnut
01-31-13, 02:47 AM
What is centered out?

Manic Mechanic
01-31-13, 10:32 AM
Have you checked the Harmonic Damper? It's common, esp. at your mileage. Pull the LH front wheel and liner to expose it and look for defunct elastomer between the hub and pulley. If you can just look down at it and see anything or it wobbles you've found it already.

Vernon

Submariner409
01-31-13, 10:48 AM
Have you checked the Harmonic Damper? It's common, esp. at your mileage. Pull the LH front wheel and liner to expose it and look for defunct elastomer between the hub and pulley. If you can just look down at it and see anything or it wobbles you've found it already.

Vernon

RF wheel - the balancer is on the "passenger side" - the front of the engine.

"Clanking" in time with the starter sure sounds flexplate/torque converter related.

You might be able to get a peek in the bottom flexplate cover - under the transmission. Can't see much through the starter opening - with the intake manifold removed.

carnut
01-31-13, 10:53 AM
A common mistake! Left and right is from the driver seat in car language!

daveyhouse
01-31-13, 04:51 PM
I didn't even think about the torque converter, been there done that also, almost the same sound as the broken flexplate I had. It was on a grand caravan with a 3.3
Sounds alot like a bent rod contacting the block or something, except it was not constant. Again it was at idle and certain unloading conditions never during acceleration, until they got too loose then it was any rpm and free spinning but not accelerating.

At least that you can check when you have starter out (1 bolt at a time).
My caravan happened about a year after garage swapped a motor for me. They never put loctite on the threads. All the bolts were loose, but I didn't loose any.

carnut
01-31-13, 05:45 PM
This flex plate is held to the crank flange as well as the outer edge of the torque converter. You can access the t/ converter bolts, but not the crank flange without at least, partially removing the transmission! as I mentioned earlier, if there is a crack at the crank flange it will in most cases, leave a rust stain down from it.

eldoradoin
02-02-13, 01:01 AM
Have you checked the Harmonic Damper? It's common, esp. at your mileage. Pull the LH front wheel and liner to expose it and look for defunct elastomer between the hub and pulley. If you can just look down at it and see anything or it wobbles you've found it already.

Vernon

You know what? You're probably on to something. I'm going to check tomorrow. I was looking at the wrong side of the motor and my symptoms sound like something up that alley. Thanks!

I had a brand new flexplate put in about a year ago.

When I said the flexplate "centered out".. was something like this
http://jaguar.professional.org/snaps/ford/flexplate_out_2.jpg

carnut
02-02-13, 01:44 AM
Thank you!

eldoradoin
02-12-13, 04:59 PM
Okay guys, here's the final verdict. Brand new flexplate, sheared and centered. I was told because the harmonic balancer was bad, the vibration travels through the motor, and and onto flexplate/tranny. Checking BOTH sides of the motor doesn't hurt. Lesson learned on this end.

daveyhouse
02-12-13, 08:33 PM
Thanks for the update.
It's sucks that a bad part at one end ruined a new part at the other.
Now I am wondering if I should change my son's while the motor is out.

eldoradoin
02-12-13, 08:43 PM
Thanks for the update.
It's sucks that a bad part at one end ruined a new part at the other.
Now I am wondering if I should change my son's while the motor is out.

It wouldn't hurt taking a look-see around, once the cradle is dropped.

edit: daveyhouse - I see you're in PA. Definitely check the flexplate. I grew up in Pittsburgh and that salt will find its way up through the bottom inspection port.

Manic Mechanic
02-12-13, 11:03 PM
Man that's rough, sounds like another Northstar hard knock lesson. Ha, sorry no pun intended. Thanks for the update as I've never seen that happen before but now I know to at least look for it when I see one or the other. My uncle gave me my DeVille with 130K on it about a year ago, mainly because it would be very hard to sell with the issues it had. One of the first things I noticed was the harmonic damper was wobbling. The elastomer was still intact and the hub to ring bond was strong but for some reason it had become slightly crooked therefore spun in a uneven way. Seeing that this engine was shifting at 6200 made me even more scared of it coming apart and doing damage. So I soon picked up a good one at a salvage yard and installed it with a new bolt. I also make sure the weight of the engine never rests on the dampener during servicing, you can never be too careful with these things. Very complex, delicate, and hard to service. If they didn't work so well when they are working we'd be scrapping them quick.

Vernon

eldoradoin
02-13-13, 05:55 PM
Well Manic, when the N*'s are on.. they are ON. My motor doesn't have tick one, and there are 214K miles on it. I believe that my downfall was when I started servicing it myself. :suspect: Good luck!