Re: Vacuum Lines, Windshield Wipers

Posted by HH56 On 2024/5/30 21:29:03

Good writeup but don't forget about the numerous oil pump "fixes" and conversions. Many cars running around have one of the versions that eliminate the crankcase aux vacuum pump. Their plumbing may look stock but may not work as advertised. The Packards International mod which removed the aux pump and added a thick bottom plate was very popular starting in the 70s and many cars have that mod. The Olds pump which never had an aux vacuum at all is now the preferred mod and that started almost 18 years ago with quite a few conversions being done since then.

Both those pump mods eliminated the second line from the balance valve to crankcase functioning as a vacuum source. In some instances the balance valve was completely removed and a single line with a tee connection powers the wiper and washer. In other cases the valve stayed but port was plugged in some fashion and line removed. To keep the completely stock look, in other cases the line to the crankcase port stayed too but was plugged and unfortunately in a few cars nothing was plugged and the hopefully functional check valve at the side of the block was all that prevented a vacuum leak.

Various methods have been tried as an aux pump replacement. Most common is to revert to a 54 and earlier style dual action fuel pump and plumbing layout. It can either be in series as was done on earlier cars or can use the discarded second source line to the balance valve. There is at least one car having an alternator with a vacuum pump on the end running around. I have also heard there are a couple of cars with aux electric vacuum pumps but not sure how any of those cars with the alternator or electric pump are plumbed.