Removing the vacuum line will leave the flap open, drawing cool air. The best thing to do is connect the vacuum actuated motor to a vacuum line that's always got vacuum.

One thing you may want to check on your flywheel... Make sure all the bolts on the flywheel are tight. This happened on my 1980 Bonneville wagon. They got loose, and it sounded like the car was knocking.

Your Eldorado is small by Cadillac standards of the time, but should still float some. Check your springs for proper ride height. If you have weak springs, or bad shocks you may not float properly. Also, that car is on a full frame, right? If its only a partial frame, or a unibody you won't get the classic "big car ride" without a lot of work.

-Jay

Wouldn't I have to drop the transmission to inspect the flywheel?

No. There is a coverplate on the bottom of the car. 4 screws and it drops right down. Tighten the bolts you can get to, then either turn the engine by hand with a wrench, or put a small dot of white paint on each bolt after you tighten it, then quickly bump the key to turn the flywheel. When all the bolts have paint on them you know you're done.

Last time I did this I was much younger, and after I tightened a bolt I just kept turning the wrench to bring the next bolt around.

Heh, I just realized you were talking about JoeBob's Caddy with the part about knocking and checking the flywheel bolts. I was trying to remember when my car knocked... :D

Yeah, You can check it on your car too, it wouldn't hurt. I just remembered that Joe's Eldorado is FWD, The procedure may be slightly different to get to the flywheel, but once you're there, the concept is the same. Make sure all the bolts are tight.

Actually, I did check the bolts that I can see...they seem to be tight. However, I did notice some of the bolts from the bell housing to the engine were < finger tight...interesting. And I noticed some sag at the transmission mounts...so I think before pulling the trans I might tighten the mounting bolts and try new trans mounts. I had noticed a week ago that if I put a jack under the engine and lifted slightly, the knock went away (of course, doing this carefully, with a board between the engine and jack).

The Cad is a lot more floaty than the Geo...and probably less than it was when new. Time, smog and miles take their toll on rubber mountings. It's less floaty than the '50s and '60s cars I grew up with, but a lot more than the '60 Chevy lowrider a friend had about 40 years ago...

IIRC, at least on the Cad, the default position of the air cleaner flap is closed, drawing warm air from the oven around the exhaust manifold. Maybe your cars are different...or my memory could be wrong...I'll have to look.

I never considered that the mounting bolts would be loose. Go ahead and tighten them and re-evaluate. Cadillacs may be different than the rest of GM, that's totally possible. I'm quite sure that the flap stays open on my Buick until the vacuum is applied. I can double check it tomorrow as I keep the Buick parked at work.

-Jay

Oh bloody hell. I run cheap parts and even junkyard parts when I get em and they work just fine.

Same here, depending on the part. Starter for the Geo, from the junkyard. 20 bucks instead of 120. Starter for the Cad, about $30 with lifetime warranty from Autozone. When I had my '85 Continental, the ABS pump died horribly. From the dealer, $2100. From a junkyard, $8.00. Junkyard unit worked just fine.

High engine vacuum should pull more hot air into the engine in a properly functional factory WAI.

As far as whether that is open or closed, does it really matter?

Open to what or closed to what? I consider a vacuum operated device open when the vacuum is operating the device, but it really is not that relevant.

As far as junk yard parts, to me it depends on how much work you have to do to install the part. Easily replaced parts mean less labor risk, but my logic was more dependent on customer satisfaction, which is a non issue when you are doing the labor yourself.

I also practiced the principle of not replacing parts that were not relevant to the customer complaint, which avoided the "hit and miss" accusations from someone who really did not need the parts replaced to solve the original customer complaint.

When their problem had been resolved and they understood the price of the repair, then it was a better time to recommend preventative maintenance, to avoid repairs that were the consequence of lack of PM.

HC, again I apologise for my first comment that was inconsiderate. Let us know what is going on and I will try to help as much as I can, but Jay is probably better versed in GM products. I have very little GM experience.

regards
Gary