Delta 88, rattling noise at idle.

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Hey, I've got an Oldsmobile Delta 88 Royal, 1988, 3800 VIN C engine, 125,000 miles. I had all of the fluids changed, transmission and radiator powerflushed, etc about 1000 miles ago. Before all of the
fluid flushes, I also Seafoamed the engine, which made it run a LOT smoother, but I don't think it contributes too much to this problem (or maybe it does, who knows?).
After a semi-rough start today (where you turn the key and it barely catches, putters, and complains until it grabs a good idle 5 seconds later), I noticed the engine makes quite a loud rattle noise at idle rpm. Right after I start it, sitting at lights (in neutral or drive, doesn't matter), or after I park, I hear the noise. If I step on the gas pedal AT ALL, the noise goes completely away. It also takes a second or two for it to come back after I let off the gas (but it does come back if I let of the gas and let it coast). It's loud enough to get other drivers to notice it when I'm driving, but it doesn't seem to affect the performance of the vehicle at all.
I tried the "screwdriver-as-a-stethoscope" test, and I didn't really hear anything from the alternator, but I do hear it loudly from either the area right below the power steering fluid reservoir (is the water pump?), and on the rear valve casing, louder on the passenger side (towards the alternator/etc). I know my car has camshaft sensor problems (as in, there's no magnet left...:( ), but that doesn't really cause any problems, besides the minor inconvenience of having to let it idle a bit after cold starts (or else it suffers from gas pedal "lag" for the first couple of minutes). This noise I'm hearing is completely new, and I'm hoping it's something that won't cost an arm and a leg, like the harmonic balancer pulley. I can't really afford to have them pull the engine and replace the timing chain (though, that'd be a good time to get a new camshaft position magnet, whatev), but if that's the problem, I'd like to know.
Anyone have any thoughts?
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Sounds like could be classic case of belt noise. If u accelerate, it slightly 'tightens' the belt & can quieten it--then be noisy when it is 'loafing'. If u know a tech who knows how to safely use a file and roughen up the grooved side of belt while running, u probably will hear the noise leave--if just for a day or so. It maybe got too clean from the Seafoam! New belt? A good brand like Gates, not AutoZone's brand. s
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So, my list of things that could be bad are: Pulley Belt Timing Chain
...?
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Pulley: highly unlikely= good news for u. Timing Chain: highly unlikely=more good news. Belt: likely=final good news for u. All my 2 cents' worth, but I'd bet 10 cents your situation is the 'best of the 3'. Luck, s
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I've replaced the timing chain on those cars and it's not bad, pulling the engine isn't necessary. Not saying that's the problem, though. I had an '88 Delta which always had a clattering noise similar to what you described. I bought the car as a cheap winter beater with 225K on it and sold it with 246K, and the noise was there most of that time and never changed. Sold it to someone else and saw it around town quite awhile after that and I'm pretty sure they never addressed the problem either, since the trans was getting weak by then and I'm sure they were going to just drive it 'till the tranny shucked out and then junk it.
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On Jun 16, 8:40 pm, snipped-for-privacy@webtv.net (James Goforth) wrote:

Well, that's cool. It's kinda my plan for the car: I bought it for $1k, with new AC system/brakes/etc. But, for being so old, it had "only" 100,000 miles on it. I kinda want to get another 100,000, if possible, though if anything costs more than $700, I'm gonna go "fuck it" and get another beater. I've put this car through a LOT, but I've also been very kind and caring when it comes to maintenance.
Though, the fact that less than 10 miles ago the car didn't make ANY odd noise means I really don't want to live with it. For being so old, it's got a bit of power ('specially after the double Seafoaming....RAWR!), and it'd be nice to not have people stare at me when I stop moving.
Does it help at all if I say the noise is in cadence with the engine? Or that turning off the AC makes it get quieter for a short period of time? I'm getting a quote Monday when I take it in for an oil change (I know how to do it, but removing a tire isn't fun) to get the timing chain, serpentine, and camshaft position sensor magnet replaced. If I don't really have to do that, that would be nice to know...hehe
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On Jun 16, 11:14 pm, snipped-for-privacy@gmail.com wrote:

Oh, and forgot to say: while I don't have any special tools for the belt, I do have a REALLY big torque wrench (swear the handle is 4+ feet long), and the serpentine belt itself doesn't "look" too bad...the ridges on the inside are SLIGHTLY cracked...but I'm no specialist mechanic. So far it's been all "oil, sensors, tires" for me.
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And thirdly: a "wannabe mechanic" said it sounds like a "broken valve spring". I don't really know what that entails, and I hope it's a case of "overdiagnosing". I was only thinking timing chain because it's the stock one, and some peeps like to change it more often than every 100,000 miles...when I replaced the spark plugs a year ago, they were STOCK. The car had one previous owner, and he didn't do anything besides oil changes.
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A broken valve spring would make noise at all times, plus the engine could possibly misfire if valve is not closing completely. Also, timing chains usually last the life of the engine, don't know personally anyone who changes them at certain mileage intervals unless the engine uses a belt instead of metal chain. Roy

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I heard something about "nylon coated sprokets"?
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On Jun 17, 2:47 pm, snipped-for-privacy@gmail.com wrote:

Oh, put "belt dressing" on the belt, didn't change anything, even temporarily. Sound seems to be coming from rear side of engine, but can't pinpoint it. Now kinda rattles all the time, but only loudly when stopped. I can get an audio sample if you guys want me to...
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wrote:

You seem rather sure it is internal, How about some external component like the air pump for the emissions system (if that engine has one)?
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Replaced the belt. Not the belt...
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Update for anyone who may want to know (or any people who may search Google Groups or something with a similar problem)
It was the harmonic balancer. I'm having it replaced as I type this. The shop says the harmonic balancer threw timing off (?) and was starting to slam valves. When I was told that, I decided to also replace the timing chain and tensioner pulley, because it's all in the same area of problems.
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klintor wrote, "It was the harmonic balancer. I'm having it replaced as I type this. The shop says the harmonic balancer threw timing off (?) and was starting to slam valves. When I was told that, I decided to also replace the timing chain and tensioner pulley, because it's all in the same area of problems." ****************************************** That's a new one on me.
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On Jun 23, 4:54 pm, snipped-for-privacy@webtv.net (James Goforth) wrote:

New one to me, to. But, I did notice that it was kinda...lopsided when I changed the oil a few days ago. I assume the harmonic balancer is the big one, down by the oil filter?
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"New one to me, to. But, I did notice that it was kinda...lopsided when I changed the oil a few days ago. I assume the harmonic balancer is the big one, down by the oil filter?" ************************************* I would expect them to first see if the noise disappears with the belt(s) removed; then swap the harmonic balancer and see if _that_ gets rid of the noise. Maybe it will.
If not, then check the timing gear, which would be a viable culprit for the noise anyway. If the timing gear has already been changed, it may not need replaced and hence all a new one will add is cost.
I'd be curious to see if there's evidence of it having been changed already, although it's possible it was done incorrectly and it's noisy for that reason.
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On Sat, 23 Jun 2007 18:54:26 -0500, snipped-for-privacy@webtv.net (James Goforth) wrote:

Be sure to replace the cam button and spring in the end of the camshaft and the plastic encased magnet on the camshaft sprocket. These items frequently fail causing a "check engine" light and (if I remember correctly) code 41 "cam position signal missing".
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On Jun 23, 4:48 pm, snipped-for-privacy@gmail.com wrote:

The car couldn't keep a tune?!?
Sorry...couldn't resist. I had an 88 Delta 88 RB, as well, and had the same problem, except when mine went the car wasn't drivable. Idled extremely rough. I hope your bill to replace it wasn't as much as mine ($500, I think).
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**************************************** $445
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