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Uh-oh. . .

'99 986 with 125K, my daily driver, just replaced my AOS with help from this board now has a host of new rattles, one of them getting worse and sounds very clang-y and varies with RPM's. Something is bad, very bad.

Started about 2 weeks ago as slight clank, like you might hear on an old 70's Caddy that hadn't seen a shop since '82. Varied with engine speed, seemed to occasionally go away when I was driving, but that may have been just that I couldn't hear it with the top down.

Now very loud. An aural tour around the engine compartment shows the sound is loudest as indicated on the pic. However it also sounds very loud just poking head underneath. Might be closer to the bottom than the top. Can't tell because I didn't have time to get it up in the air and investigate. When I came from work it was so bad, I took it right to the shop.


Don't know if this board has sound capability, but here's a couple of MP3's about how it sounds. The first is holding recorder right over the spot where the bullseye is. Second is moving recorder from L rear of car to R rear, then to the bullseye.



Even though it's in the shop, shops don't always get it right, and I've never known this board to be wrong, even when making calls against the shop. So, what say you, Renntech?


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I'm not a Tech but it sounds to me like you may have not tightened/connected something completely when installing the AOS or perhaps there is a hole/leak in one of the tubes or connectors. Also on the first sound file there is a dip in the idle that would indicate the system does not have the proper vaccuum (unless you were barely moving the throttle.) Maybe it came a little loose while driving the past two weeks.

Edited by fasterjames
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It's difficult to say without hearing the car in person but I'd say you need to check the oil for engine goodie. Drain the oil through a paint strainer so you can study any debris that may be present. Then remove the sump cover from the bottom of the engine to investigate further should you feel the need. Once you have removed the cover you'll be able to see the sludge that has built up on it and check for metal fragments. You'll also be able to see the bottom end. I don't want to freak you out but it definitely sounds like it could be deep and nasty. It could just be something stupid but going straight to the oil will tell you how serious the issue is immediately and may help put your mind at ease.

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Thanks all, for the helpful input.

Answer was the water pump, believe it or not.

Fixed now, but cost me $300 in parts, $300 in labor. S'okay, because it coulda been much worse, but I'm kinda bummed because I wanted to try my hand at fixing it myself. Oh well. Car sounds great, runs great, and I got out for under a grand.


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That's great! You just never know these days who the next poor guy to replace his engine will be. :(

Hey! I resemble that remark! Watch my saga unfold in my IMS failure thread. I'm very glad for this gentleman that he got off with a light spanking...


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This, a quote from Jake Raby, from another thread:

"When I hear any complaint of a rattle in the engine I immediately recommend having the IMS bearing checked for issues.. Thats because if caught early enough it can be repaired... Sometimes 1 mile of driving can make the difference in salvaging the engine or not.

Lots of things can rattle including water pumps, pressure plates, A/C compressors and the list goes on.. None of those rattles are more critical than that of the IMS bearing. Thats why ANY rattle should be taken seriously and looked at immediately!"

Looks like you truly did luck out on this one!

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