Delta 88, rattling noise at idle.

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?

Reply to
klintor
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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

Reply to
sdlomi2

So, my list of things that could be bad are: Pulley Belt Timing Chain

...?

Reply to
klintor

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

Reply to
sdlomi2

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.

Reply to
James Goforth

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 "f*ck 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

Reply to
klintor

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.

Reply to
klintor

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.

Reply to
klintor

Reply to
ROY BRAGG

I heard something about "nylon coated sprokets"?

Reply to
klintor

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...

Reply to
klintor

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)?

Reply to
Edwin Pawlowski

Replaced the belt. Not the belt...

Reply to
klintor

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.

Reply to
klintor

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.

Reply to
James Goforth

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?

Reply to
klintor

"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.

Reply to
James Goforth

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".

Reply to
Chuck B.

" For being so old, it's got a bit of power ('specially after the double Seafoaming....RAWR!)..." *************************************** What exactly is the 'double Seafoaming' you're talking about?

Reply to
James Goforth

******************************************

Seafoam is an anti-carbon additive: you can put it in your gas tank (to maintain injectors/pump, kinda like Techron), directly into your crankcase to "dry out" oil, like HEAT, or (my favorite) directly into the engine to remove buildup. For my car (since it's an automatic), I pour it directly into the powerbrake vacuum line; pouring it in there pulls it directly into the engine, and makes it puff smoke out of the tailpipe. The first time I did it, the smoke that it made was a really dark brown (supposedly, that's the gunk it's cleaning out). The second time I did it (hence the "double"), the smoke was lighter, almost bluish (like burning oil, makes sense since it's a petroleum product), but still brown. After "Seafoaming", you take the car for a spirited drive and watch as it smokes up the whole neighborhood. Also, after Seafoaming, you'll have to change the oil, especially on old cars, because a bunch of buildup will drop into it.

I used the Seafoam right after changing my oil, and had to change it immediately thereafter because it turned the oil a pitch black. The good news is it gave my car a TON of power, and also smoothed out the idle a great deal. I was afraid the Seafoam had done something to my car; the bottle itself warns about doing it on cars with more than

100,000 miles because removing the buildup can also remove what's left of seals and gaskets. There have been a couple of stories of people using the Seafoam and immediately starting to burn oil, or blowing a head gasket altogether. But Seafoam isn't going to completely smash my harmonic balancer, so the two were probably mostly unrelated (I hope).
**************************************

Actually, I've had code 41 for a LONG time. At first it was intermittent, then it became constant. I've replaced the sensor and the wires themselves to no avail, and have just come up with the conclusion that the magnet itself is completely gone. The shop I took the car to flat-out refused to replace the timing chain, and said that it would cost a bit to replace the damned $2 magnet. I'm tempted to turn the engine over manually and epoxy one in there...I saw a guide for it floating around the intertubes awhile back. I didn't think it would be anywhere NEAR $1k to replace the magnet, especially since it's right there on the big timing chain sprocket. Since they weren't actually going to replace the chain, they never opened up the area. Any advice you guys have on this would be nice, too :)

Reply to
Geirskogul

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