'41 Cadillac Convertible power top help

[Jim H]

My vacuum operated top hissing, not working. Are there any drawings, vids, articles, parts diagrams, or anything else out there showing how the vacuum pump operates/vents, etc.?

 

Not addressed in my skinny Shop Manual for '41

 

Thanks, 

 

Jim

[Marty Roth]

Hissing would imply a cut, rotted, disconnected hose.

check first under the dash to see if you inadvertently bumped a hose at the switch for the power top as you used the hand brake.

 

Also, it may take a modest amount of time to build vacuum before the top will operate, and sometimes may need a bit of assist off the windshield frame and up a few inches so the system will pull .

 

Good luck. Mine has worked flawlessly since I got the car in August, 2006.

Edited April 19, 2020 by Marty Roth (see edit history)

[Jim H]

Thanks, Marty. No loose connections, just doesn't have the oomph it needs. 

 

still looking for any shop drawings, etc GM might have produced re the vacuum pump.

 

Nice looking car there!

 

Jim

[Matt Harwood]

The system is shockingly simple. There is no pump, it simply uses engine vacuum so the engine needs to be running at idle for the system to work. The engine itself needs to be healthy, so hook up a vacuum gauge to the intake port and see what you've got. Should be 17-21 in hg vacuum on a healthy, properly tuned engine. The rest is just hoses, the switch under the dash (which can be problematic), and two vacuum pistons in the top well. The most likely cause is a leak, either in one of the hoses or the vacuum cylinders (which I believe are available from Hydro-E-Lectric). Then check the switch, which should have some kind of diagnostics in the manual--these are often part of the problem. Finally, be sure you are using the correct type of hose, since that much vacuum and that kind of load will collapse incorrect hoses--all rubber hose is not created equal and it needs to specifically be hose designed for vacuum applications. If it's collapsing somewhere, that would give you the weak response you're describing and most people doing this in their driveway may not even realize that they're using the wrong type of hose. Just because they're intact doesn't mean they're doing their job, and there's A LOT of hose in that system.

 

The system is reliable and easy, but all the components need to be healthy. Those cylinders will lift an engine block if they are sealed and have vacuum.

 

 

Edited April 20, 2020 by Matt Harwood (see edit history)

[kgreen]

If the seals are dried out in the switch or the cylinders, a little oil on the leather can temporarily rejuvenate the seal.  Old trick from Coleman camping stoves with air pump used to pressurize the gas.

[Jim H]

Thanks to all!

 

Seals were bad and we replaced with thick felt - all good now.

 

Jim