No, it's not the heat shields. Those have been off for a long time. And it doesn't seem to be any of the accessories - PS pump, alternator, compressor. etc. I get a funny rattling that is slowly getting worse that is coming from the engine compartment, but it seems to be coming from the engine or maybe the transmission. It's hard to locate the sound. Although it does sort of sound like a heat shield rattling, it's not that. The way I could also describe the sound is that it sounds like a bad timing chain on a car with a timing chain. But a little more intermittent.

The latest thing I've noticed is that it seems to only happen when the transmission (auto) is engaged, and not when it's in neutral.

I know that the motor mounts need replacing, and that the engine shakes more than it should.

Anybody have any ideas what it could be? Is there a serious engine problem that sounds like what I'm describing? Or something with the tranny? Thanks for your thoughts, this is sort of stumping me.

Has the transmission ever been removed? If so the torque converter to flex plate (flywheel) may be loose. When it's in idle they won't make much noise but when you put it in gear they will. There are a couple of inspection covers on the lower transmission bell housing you can remove to check these bolts.

Hope this is it...

Good Luck...
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Volvos4me4ever 1989 245 273K miles still going strong, 1992 745 Turbo 110K miles real nice!

If those broken motor mounts have shifted they could be allowing metal to metal contact between the engine and frame. This will vibrate the whole car (and your fillings).
steve

Same symptoms I had before the catyltic converter went to hell. I'd say take off the cat and start the car, but thats loud as hell and you wouldn't be able to hear the rattlign if it was still there anyways. If you have a known good cat with exhaust, try bolting that up. I'm telling you I had the same symptoms and then bam, one day my car would not accelerate over 30 mph, and it was a struggle to there. Talk about back pressure

If everything else is ok, this could definitely do it.
I'd want to rule out engine mounts first, but a new cat is only $125, so maybe thats the way to go. Surely the original 1988 cat is on its way out anyhow.
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Rob Bareiss, New London CT ::: '87 244DL/M47- 234K, '82 245T/M46-182K, '89 244DL/AW70- 212K Not too distant past: 86 244DL 215K, 87 244DL 239K, 88 744GLE 233K, 88 244GL 147K, 91 244 183K

Provide a link to your original post.
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Art Benstein near Baltimore

Actually, this post has all of the relevant information and symptoms. The "news" is only that I just noticed that the sound happens more when the transmission is in one of the forward gears or park. When it's in neutral it usually goes away.

Of the many well thought out responses in your original thread http://www.brickboard.com/RWD/index.htm?id=856633 I kind of like the only one you cared to comment on.
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Art Benstein near Baltimore

I'm not sure what you mean. Do you mean to say that you think it's my Scantech tensioner going bad after less than 15K? I suppose that's a possibility. I checked out most of the other suggestions (my cat is also fairly new - less than a year old - Bosal cat from FCP; although it's too early normally to suspect it, again anything is possible I guess....)

I posted new because I think it's significant that it only makes the sound when the transmission is in gear, which I just noticed yesterday.

Hi Bruce,

I like the response because it fits with my experience with a rough tensioner bearing, louder while the motor is under load. Like the loose heat shield, it will make a racket next to a wall in drive, but get quiet in neutral, though the sound is much different. Your timing chain description is also a strong influence on my attempt to "hear" your car.

But matching symptoms with causes is only guesswork without investigation, and I'd supposed after three weeks you'd have made that suggested stethoscope and ruled out those exhaust pipe and cat possibilities.

To isolate motor mount and body contact noises, try it in reverse-- the noise would change. A rough tensioner wouldn't care if the car was straining in reverse or drive.

Just be very careful poking around with a hose or cardboard tube with the car idling in drive. Have your wife keep pressure on the service brake. But first, make sure she's happy with your work on her car;-)

Neither cats nor tensioners die purely because of age, though you are right to expect one to live more than 15K.

Thanks so much for your helpful input. In three weeks I haven't been able to work on the car much or even make that stethoscope. I have this weekend to myself, so hopefully I can track this down once and for all after I change out the master bedroom window!