Stovebolt.com
Posted By: Steve1940 1959 235 blow by - Mon Jun 01 2020 09:36 PM
Hi, Has anybody installed a crankcase evacuation system on their 235 looking for pros and cons on this? Thanks Steve
Posted By: panic Re: 1959 235 blow by - Tue Jun 02 2020 01:49 AM
crankcase evacuation system
Vacuum pump?
Exhaust connection?
PCV?
Posted By: drdoug Re: 1959 235 blow by - Tue Jun 02 2020 01:56 AM
The factory had an RPO for commercial vehicles that added PCV for vehicles that wouldn't be on the highway for the most part (making the draft tube ineffective), and an optional kit (shown in the drawing for '55). Note in the image how tall the breather is that replaces the draft tube. It was designed to avoid pulling too much oil vapor into the intake system.

But sure, it can be done. Best bet is to keep the baffling of the draft tube in place, and modify for a 6 cylinder PCV valve (occasionally one of the NOS or used factory PCV set ups show up on eBay, but they are rare at this point). The valve cover should be sealed of course, if the engine has one with the breather slots (model year dependent), and a better inlet connection designed. Note the factory mod has a tube running from air cleaner to valve cover added for that.

Hope this helps!

Attached picture 417-1.gif
Posted By: Steve1940 Re: 1959 235 blow by - Tue Jun 02 2020 10:57 AM
Thank you for the info on that A older gentleman said I should look into that to let more crankcase pressure out .
Posted By: tclederman Re: 1959 235 blow by - Tue Jun 02 2020 11:29 AM
Steve,

What year 235?

Does it have a road draft tube?

Have you inspected/cleaned the road draft tube?

If your engine has a non-clogged road draft tube, there should be no "engine/crankcase pressure".
Posted By: Steve1940 Re: 1959 235 blow by - Tue Jun 02 2020 07:10 PM
Hi Tim, It is a 1959 235 and has a road draft tube. I was planning to clean it today but have not got around to do it. Hope to do it tomorrow I will report back. Thanks Steve
Posted By: panel fan Re: 1959 235 blow by - Tue Jun 02 2020 11:28 PM
Originally Posted by drdoug
The factory had an RPO for commercial vehicles that added PCV for vehicles that wouldn't be on the highway for the most part (making the draft tube ineffective), and an optional kit (shown in the drawing for '55). Note in the image how tall the breather is that replaces the draft tube. It was designed to avoid pulling too much oil vapor into the intake system.

But sure, it can be done. Best bet is to keep the baffling of the draft tube in place, and modify for a 6 cylinder PCV valve (occasionally one of the NOS or used factory PCV set ups show up on eBay, but they are rare at this point). The valve cover should be sealed of course, if the engine has one with the breather slots (model year dependent), and a better inlet connection designed. Note the factory mod has a tube running from air cleaner to valve cover added for that.

Hope this helps!

Drdoug . Please explain the need for the tube running from the valve cover to the air cleaner . I have a 261 with a similar pcv but not a tube to the valve cover . I do have a vented breather cap .

John
Posted By: Hotrod Lincoln Re: 1959 235 blow by - Tue Jun 02 2020 11:43 PM
John, either setup will work, as long as there's a way for air to get into the valve cover. After 1968, the "Clean Air Act" in the USA mandated "closed" ventilation systems that put air from the "clean" side of the air filter into the crankcase so there was no possibility of fumes from the crankcase getting into the atmosphere. GM's PCV setup in the 1950's did it to assure no "dirty" air could enter commercial engines and promote abrasive wear. If the vented oil filler cap has some type of filter built into it, the same thing will be accomplished.
Jerry
Posted By: drdoug Re: 1959 235 blow by - Wed Jun 03 2020 12:58 AM
John, Jerry covered your question nicely. Either the "clean air" routed from the air cleaner to the valve cover, or a vented filler cap with internal filter will work just fine.

Doug
Posted By: panel fan Re: 1959 235 blow by - Wed Jun 03 2020 01:05 AM
Thanks to you both for the clearing this up for me , I was clear on the what and the how but not the why !

John
Posted By: Steve1940 Re: 1959 235 blow by - Wed Jun 03 2020 10:30 PM
Hi, Road draft tube was real dirty I cleaned it out real good so should be good to go . Thanks for all the help. Steve
© The Stovebolt Forums