The Stovebolt Site Forums The Shop Area Engine Shop PCV valve

Installed a pcv valve in my 235 as per Deves instructions and it’s sucking my oil out. Any ideals what’s going on?

Maybe post some pictures of your setup for folks to look at so they can offer some thoughts/solutions.

That setup is not ideal. The pcv valve should be located much higher on the engine to avoid that problem. That's why factory installed pcv systems place the valve in the air cleaner.

It will help Bolters help you if you can post pictures of your set up and provide more details. I would also have to agree with Otto that the system you are trying to install has some design issues. The valve needs to be mounted well above the oil pan level if you look at original GM PCV system designs (pic below from the FAM). IIRC, the tube installed into the block draft tube hole also has a built in baffle to prevent oil being drawn up and into your intake.

Check out other PCV conversations like this one started by "ol 55". There is another link in "ol 55's" post to a thread by "Hanks custodian" that is also great info. Come back and show us what you have.

Compare your reference source to the way GM designed the PCV system. The right way to do it should be glaringly obvious. The valve needs to be located approximately level with the rim of the valve cover, and on the downstream side of an oil/vapor separator baffle.
Jerry

Here is a picture of the factory setup. It can be somewhat duplicated by using the original draft tube, cutting off the draft down tube a couple of inches from the riser tube, welding on a washer sized to a grommet that is sized to fit a PCV valve.

This mod has been discussed in this forum. Do a Search and you should find it.

I agree with what’s been addressed as to the location of the PVC valve needs to be higher. I still don’t know how Deve kit is able to installed without a draft tube.

Thanks guys for all the feedback. I am going to reinstall my draft tube and do some more research on the Pcv system. I have duel Weber carbs from Tom Langdon. When I put a tee at the manifold for the Pcv system it drastically affected my wipers.

Does that mean they worked better, or did they work worse?

Either way, forget about the wipers and use RainX. I use it on all vehicles, even those with functioning wipers. It's great. How often are you driving your antique truck in the rain, anyway?

By the way, what year truck is it?

I have a 1952 3100 with 1950 doors. Langdon two carb set up and the Patrick 3:55 rear end. Wipers are worst and I agree about how much their used. Will post pictures once I figure how to.

Could it be that he has no idea whatsoever what he's talking about? Most of the people on this website figured that out quite some time ago!
Jerry

My truck is a1952 3100 with 1950 doors. Langdon two carb set and Patrick’s 3:55 ring & pinion. Agree with you about the wipers. Question, should I use the Pcv system or stay with the draft tube.

Not trying to hijack but what a really nice RED truck.

That would depend on your driving habits and whether you are strict about oil change frequency.
Crankcase ventilation with a draft tube would be just fine if most of your trips involve going over 25-35 MPH. That is the speed at which crankcase fumes will be sucked out via the draft tube. Below that speed, not so much.
PCV would be better if you were a delivery driver in a city with lots of stops and starts with lots of idling, where you seldom go over 25 MPH, or if the only driving that you do is on and off of a trailer.
Crankcase ventilation is important for removing blow by fumes which will contaminate the oil which will wear out bearing surfaces and rings prematurely.

I was referring to PCV kit available from Deve Technical Network. My observation was too short and I neglected to state that Deve’s kit is installed without the draft tube and I’ve not seen any complaints about his kit causing issues.

With the proper PCV, the vacuum loss should have very little effect in the wipers. The factory installed them on big trucks for years. I didn’t notice any effect after installing mine. Vacuum wipers are affected by low vacuum which occurs any time you step on the gas. Not the best system which is why they went to electric wipers.

My vote is to stick with the PCV, but either buy a factory riser tube, (rare but the’re out there), or modify your existing draft tube to get that PCV higher. You can’t keep it where it presently is.

I found a NOS riser tube on eBay a few years ago and they were installed on big bolts for years.

If simply replacing the road draft tube with a freeze plug and a grommet would work, why would the GM engineers go to the trouble to build a standpipe with baffles in it, and place the valve high above the crankcase? The entire idea of putting the PCV valve down where it can pick up oil splashed off the crankshaft is ludicrous. Even though there's a sheet metal splash shield inside the block, it cannot do an adequate job of preventing liquid oil from being sucked up by the manifold vacuum. The freeze plug and grommet setup is an ill-conceived Rube Goldberg approach to crankcase ventilation which cannot be successful. If you don't have access to an original PCV setup, it's pretty simple to cut the road draft tube off, weld a threaded bung into the canister, and position the valve high enough to let gravity keep oil from being sucked up and burned. It can be done with various off the shelf components from any hardware store. There are also several varieties of PCV valves with different flow volume, depending on engine size, that won't cause excessive vacuum loss and poor windshield wiper performance. Try a PCV designed for a 200 cubic inch engine or something similar- - - - -maybe a Ford 200 6 cylinder, or maybe the old 170 engine used in an early Falcon.
Jerry

If I was inclined to add PCV to my truck, I would put the PCV valve in the top of the valve cover, maybe in a hole drilled in to the stock oil cap.
I would then find a draft tube from an older model 216 or 235 which had the oil cap on top of the stand pipe. I would then put a vented cap there.
Why?
1) No issue with sucking oil out of the crankcase, or having to do anything to the stock draft tube except for plugging the hole in the bottom end of the down pipe.
2) Having the PCV valve at the top of the valve cover will scavenge the volatile fumes and steam which tend to collect on the underside of the valve cover with no way to get out unless there are multiple slots in the top of the valve cover. (The original slotted valve cover allowed these fume to escape while the vehicle was not in motion. These slots were an integral part of the crankcase ventilation system over and above merely being holes for fresh air to enter as blow-by contaminants were being sucked out via the road draft tube.)

If you find and use the factory standpipe setup I would advise against running the pipe to the manifold over the top of the valve cover unless you have hydraulic valve lifters, which few trucks did. Route it around the front along with the factory fuel and dizzy vacuum lines. Even that is a little crowded so I routed mine below the thermostat housing.

Regarding vacuum: The PCV will oscillate and cause idle speed to vary if it's set too high and the leakage from multiple throttle blades and loose throttle shafts will contribute to the problem. I worked for some time to get the twin-carb (zenith 228) linkage synchronized and the idle speed set low enough at 600RPM. All seem well now.

However, I have a large vacuum port for the Hydrovac that uses a large, trailer, air-brake tank as a vacuum reservoir, left over from pulling a hay trailer with vacuum brakes. There apparently is a leak somewhere that I haven't chased down yet; and until the air is purged from the vacuum tank the idle is erratic after startup when it's sat for a few days. Doesn't happen overnight. But I think any vacuum leaks will cause erratic PCV operation at idle.

I converted my '58 4400 by modifying the Road Draft tube. I removed the tube, cut off the down tube and welded the hole closed. I then welded the down tube back on just for the look. I remove the top cap and fashioned a baffel to help with oil control on the engine side. I cut a hole in the cap large enough to accommodate a Valve Cover gromet. Refit the cap and installed a PCV valve. The rest was just bending up tubing and installing a fitting in the intake manifold.

This was a year and a half ago, so far no noticeable oil consumption.

Which PCV valve did you use? I have a similar set up with the draft tube, and the used the PCV I had laying around (Standard V100 threaded), and the setup causes a loud hissing, and my wipers are useless now. I am down sizing the valve and checking for leaks, wanted to know what valve works.

I used a Standard Ignition products V237. I'm not certain that will be any help to you though, I have a factory electric wiper motor on my '58. It sounds as if you do have a massive vacuum leak with your setup. It shouldn't be that difficult to pin point the source.

Hi Youngster - - So, If for some 'reason you were to install your PCV valve' up and into your 'Valve Cover' , You would also need too install a (some type) of a "baffle , inside your V-C .
From your current PCV install , I really think you have it located way tooooo low.
I can also 'relate about the vac wiper = going to slow , as my 53 IH , uses those Vac Wiper unit .................. and they don't work , any.
I'd also like too say - that I like your Twin Carb set-up ; very cool !

I use my factory 250ci engine , with the Holley 390, 4bbl carb ; and I have the M E Wagner DF-17 PCV valve (it work great , with an oil catch can) . My PCV valve , is in my valve cover.

jim

If it helps anyone, I have an old post on my blog that covers what I use to do, including the PCV valve I used. https://chev235guy.blogspot.com/search/label/235%20PCV?m=0

I understand why the road draft tube was discarded in favor of the pcv system. I also realize that in normal, everyday use when these trucks were new, the build up of blowby, acid, etc. had a detrimental effect on engine oil and internal components.

Today, most of these trucks live pampered lives, never operating in severe conditions, using modern detergent oils, driving only a few thousand miles a year, and receiving oil and filter changes regularly. Is there any real benefit to the 216/235 engine that will be gained by converting to a pcv system from a road draft tube?

Otto,
Thanks for asking that question for I would also like to know for my 235.

The only reason I installed PCV systems for customers was because they complained about the smell in the cab from blow-by

I’m a PCV believer. The stink-reduction is a nice, but my truck actually runs better than it did with the draft tube. Only thing I can figure….is that the already worn rings don’t have to fight the pressurized crankcase.