Rattle under load...

Are all the exhaust components tight? From the header gaskets to the cat?

could that rattle only under load?

Definitely! I had an Audi with an automatic that made rattling and grinding noises when you would take off from a stoplight, but when in park or neutral, you could rev it and it wouldn't make any noise. I thought, oh great, the tranny is gone. I checked underneath and was missing a rubber exhaust donut and the manifold was getting a little loose.

Good luck!

Ooo! Hope! I'll have to take a look...

It could also be pinging! I have had two black 164 (a 164L and a 164S) and they would both ping under load at warm days on CA highest and finest 91 gasoline. The pinging I had in both cars could be mistaken for a rattle, and I wished the the 12v had knock sensors and associated timing retard.
Jes

Jes, were those two 12v cars bone stock? Yeah, the 91 octane kind of sucks...

Yup, bone stock, top condition cars. This was back in 1996 - the S only had 45k miles on it. I should probably clarify that it happened under significant load and warmer than usual temps, e.g. going up somewhat steep hills at somewhat low RPM. Driving on trips in the desert was a real problem.
Jes

hm... just tried a grade lower octane this tank... maybe I'll go back up and see if the sound goes away. I've heard pinging in other cars before and this definitely sounds like a rattle, but I could be mistaken. That would certainly make the top ten of easiest Alfa fixes!

rkundrat said:

hm... just tried a grade lower octane this tank... maybe I'll go back up and see if the sound goes away. I've heard pinging in other cars before and this definitely sounds like a rattle, but I could be mistaken. That would certainly make the top ten of easiest Alfa fixes!

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Thats your problem. Do the math. Going to a lower octane does not save you much and may cost you more with the amount of pinging it is doing. 91++ is the only way to go.
Get some octant booster or just wait until half tank and fill with 91. Just keep it cool until you get the low octane out of the system.
Jason

Lower octane in an S, naughty, naughty? Don't do that. The little money you might save at the pump could really cost you. Drain it out for your lawnmower, and refill with what it calls for. They rattle a little on steep hills even with 91, Don't make it worse.

I'm glad to hear that I am not the only one who gets a little pinging at times in the heat of summer (taking off from a dead stop occationally) even running nothing but premium. I have run mid-grade a few times when the shock of high gas prices was hitting, but I went back up, because it became obvious premium was really the only way to run this car.
Charles

My car still pings at almost 200,000 miles. I think its a good thing, just means it still has good compression!

Well I hope it is just pinging. Tank is near full with 89, so I threw a bottle of octane boost in for what it's worth. Will drive it lightly and then go back to 93 and see if the sound disappears...

rkundrat said:

Well I hope it is just pinging. Tank is near full with 89, so I threw a bottle of octane boost in for what it's worth. Will drive it lightly and then go back to 93 and see if the sound disappears...

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YOU GUYS AND YOUR TOYS! I run low lead 87 octane in my SEDATE 164B sedans without a problem and get on them with full throttle take offs and have no pinging. Maybe it is the 10% corn additive that we have in VA that makes the difference or the .5 CR you S guys have over me? I have no pinging.

You are just lucky, but then again, my wife's Milano doesn't ping either. Of course, it is a bit slower than the S.

Del said:

You are just lucky, but then again, my wife's Milano doesn't ping either. Of course, it is a bit slower than the S.

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My S hardly ever pings even in the high heat, only once in a great while under hard load.
I have never used anything under 91 octane and I do have a chip.

Just be careful.
j

Filled up with 93 and it's gone... Last time she'll ever see mid-grade! Thanks for the help.