Hey everyone,

First post on the forum, but longtime reader. I’ve spend a good few hours trying to find details about my particular setup, but I would love some second opinions.

I just bought a 1986 2WD toyota pickup with 106k miles and one of the previous owners has put quite a few modifications on it. It seems he knew what he was doing but the way he setup the valve cover breather and pcv valve has me scratching my head.

He has a breather filter sitting on the pcv valve in the rear and an open vented oil catch can coming off the front valve cover vent. The oil catch can fills up pretty quick (equivalent of filling up completely - a bit smaller than a soda can- over about 700 miles of 65mph highway driving). It fills with a low viscosity oil looking substance, almost like water, with a cream foam atop it. The filter on the oil catch can drips even when not full. The same stuff sits atopt the pcv valve when I take the breather filter off.

My current thinking is that the current setup fills so quickly because the vapors are getting pushed up through the open front vent and into the catch can instead of the good oil draining back into the valve cover because the catch can is mounted lower than the valve cover. But what’s in the catch can is still pretty watery which doesn’t seem like it should be going back into the engine?

I’ve been thinking of changing the configuration to have the PCV valve go into the oil catch can then into the intake manifold (I would relocate the catch can to be closer so less hose would be needed and install it lower than the valve so nothing flows back onto the pcv valve). No external filter on the catch can as this would defeat the purpose of the IM vacuum. I would then put the breather filter on the front valve cover vent. This seems to be the more typical setup with the addition of a catch can between th PCV and IM.

My question to you all is why would one set up the engine as it sits in the photo and should I change it?

Ill be putting a dual row timing chain on soon and will be dropping the oil pan to check for any sludge buildup.

Thanks for all the help! I look forward to finally being a part of this forum.

 

Just bumping this thread, I figure it got lost in the sauce during the new years.

 

Welcome

Looks to me like you have no functional Positive Crankcase Ventilation system at all.
Just a catch can.
The PCV valve under the filter likely reduces any flow in either direction thru the filter to near nothing.
A functional system uses intake vacuum to create negative crankcase pressure and the PCV valve on the valve cover is what moderates this suction.
Your proposed changes would appear to restore the system to functionality.
This restoration might require some change to carburation, I don't know....
Unless the engine has excessive blowby, the catch can, and any filter, for that matter, should not really be necessary, but probably can't hurt.
Sounds to me like you are collecting volatiles and a little condensation moisture that an engine that is in decent condition and operating at correct temps would easily combust if returned to the intake stream by a PCV system in stock configuration.
My .02

 

Thanks for your insight! I certainly wonder why the previous owner set it up that way. You’re right, very little air is flowing through the filter on the pcv valve due to no vaccume from the IM.

I’ll go through with my changes and update this thread once I do. I’m curious as to how much gets caught in the catch can via pulling from the pcv valve instead of pushing through the front valve cover hole.

 

the weber should have a fitting on the underside of the filter bottom to attach a hose for the pcv filtered air source, and the manifold or carb base should have a port for vacuum.

this is on the 258 in my cj5. you can see the vacuum port on the manifold, and the filtered air hose. many webers have a port source on the manifold adapter itself - i used an existing port on the manifold.

 

Figured I should finish up this thread. The catch can photo is after 3000 miles after a partial rebuild (dual row timing chain install with new head gasket) on the new pcv setup. Not much of the white sludge anymore. While taking the head off I noticed I had huge amounts of carbon buildup on the intake valves. Hard to know exactly what the timeline of the engine was before me so I’ll just keep an eye on it. Engine runs so smooth after the rebuild




Also side note, the idle vacuum advance was disconnected before but I added it back in (hooked up to the intake manifold with a 1/8” JSPT barb fitting) and it seems to idle better with it connected.

 

putting the catch can back in was a smart idea, because putting the blowby vapor directly back into the intake contributes to buildup on the backside of the valves and in the combustion chamber... toyota figured that out years later, and put internal catch cans in some(all?) of the ur-series motors, if i recall correctly.

after watching ray nada on youtube struggling with getting an optimal crankcase pressure, using a pcv alternative(linked), i started trying to do it with my 22re using the factory pcv and adding a catch can like yours: https://digital.allchevyperformance....street-engine/

it started because i kept having these difficult oil leaks, like at the back of the valve cover, and now that i have created a no-internal-pressure crankcase situation, the leaks may have all gone away, knock on wood... i had to monitor the crankcase venting with a gauge to understand what it was doing, and in the beginning i increased the crankcase pressure, the engine was blowing oil out of several seals and even the head gasket(!)... we'll see how it holds up on a long trip, which is the acid test.

 

Hell, I've been trying to figure this out, I hope you don't mind me jumping on your post.
Problem is mine is boosted.
Ive been wondering if I can tie my pcv into the brass T on the intake manifold.

Would I want to go
(pcv) - (oil catch) - (check ---》valve) - (Brass T)

Or is there a better way, since this would only give me vacuum when not under boost.

 

from what i've read, people run check valves to keep boost out of the pcv and the brake booster.

is there a port with vacuum at the bottom of the carb, before the supercharger?

 

yeah, the adapter (from supercharger to carb) has a vacuum port with my brake booster... booster has a check valve before it the check valve is stock.

That would probably make more sense to tie into.

 

i got one of these vacuum gauges and wedged it between the dash and the driver-side window frame, haven't needed to screw it down yet... ran some cheap clear hose to the efi plenum, it collapses a bit under vacuum but the readings still respond really quickly: https://www.harborfreight.com/fuel-p...ter-62637.html

maybe with that you could figure out if there is enough vacuum to draw on a pvc, thru a catch can??

i ended up splitting the hose out of the catch can into two ports on the plenum, which seems to have stopped the oil leaks, the gauge says that the crankcase never goes into a positive pressure reading.

in your case the boost must be blowing past the rings to some minor extent, more than a normally aspirated motor... it would sure be an interesting experiment.

 

Yeah, that's probably not a bad idea. I've already got a boost gauge, what kinda vacuum should I be looking for?.... If I can get a damn thermostat that doesn't stick in this thing. 😒

 

my vacuum readings in the plenum are all over the place, but seldom under the 20hg range on the face of that gauge.

i'd be hoping for no positive pressure in the crankcase.

when i first put the catch can in, i used a small amount out of the metal baffle mesh that came with the kit, and it was too much, i had oil blowing out from multiple locations, including a head gasket oil leak on the side of the engine :-/

 

Interesting, Do you not have a vent on the front of the valve cover? Im guessing my air filter in the front is being used as an exhaust for the positive pressure so Im not blowing seals.

But from what Ive come to understand the front one should be used as an air intake while the rear is vacuuming out through the pcv.

Also, isnt the pcv a check valve.... putting another check valve inline with it seems redundant. Positive pressure from the intake manifold should close the pcv while vacuum opens it????

 

i think that the pcv operation you posted matches what i've read wrt how it works on an efi system... all of the air is metered, including what is in the crankcase, and a rough test for how well it's working is to plug that front hose and plug it's connection on the valve cover, then put a balloon or finger off of a rubber glove on the open end of the dipstick, see if it collapses or expands at idle.

one thing i don't understand is why toyota moved the end of that front hose location from the throttle body to the plenum(early 22re vs. late 22re), gotta take a closer look at the early throttle body to see where the hose passageway comes in, wrt the throttle body plate... is it in front of the throttle plate? if my 22re plenum is pulling vacuum all the time, how does it get fresh air into the crankcase? maybe i have too much vacuum on the pcv, and it's supposed to occasionally have positive pressure? ack :-0 i guess i'll find out, based on how much oil gets sucked into the catch can... i don't know how gunked up the baffle under the valve cover is.

carbed i have no idea, i'm guessing that it should have been a closed pcv system on the 22r?? i wonder if the baffle under the valve cover is different, from what is on the 22re... i also don't know where the 22r pcv is pulling vacuum from, i'm guessing that it's teed off to it's own system, before the check valve on the brake booster... it probably isn't hooked up between the factory check valve and the brake booster?

 

The carb has a little rubber 90 that goes from that black pipe to the front hole on the valve cover. So it gets fresh filtered air in the front and gasses vacuumed out by the pcv. The efi gets it from the front of the throttle body. So fresh air the same?

 

thx, it looks similar to the efi concept.

that late 22re photo shows both ports on the valve cover going to the plenum, which is why i don't understand how the front port is supplying fresh air if it's getting vacuum from the plenum, but that's probably not relevant to your carbed situation.

 

That's actually out of an 85 4runner 22re, that does seem weird if its vacuum front an back.

 

thx for the correction, i had it backwards, shoulda seen it with the tilted throttle body, it was early 22re that had both hooked up to the plenum... btw, i found this supercharged 22r, not sure what he's doing with crankcase vapors: https://www.holley.com/garage/view/8...toyota-pickup/

 

one of the blog posts in that supercharged 22r link showed this, but it looks like he altered that in later photos: