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2.3L ('83-'97) Overly High PCV Pressure


ylidk

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Hey all, I've been test driving my 1991 ranger with a 2.3 turbo motor from a 1988 thunderbird turbocoupe in order to get it tuned after being rebuilt and assembled. After these drives, I've noticed a lot of smoke from the engine bay coming from oil that is being sprayed around and hitting the exhaust, which is coming out of the air filter at the back of the valve cover. The Engine is building up enough pressure that it actually ejected the filter from the grommet holding it in, and I am not entirely sure why it is.

The engine is bored 0.040" over, with forged rods and pistons, and has a Big R T3/T4 "stage 1 upgrade" turbo. The PCV system is mostly stock from the 1988 turbocoupe, woth a hose coming from the block and through the pcv valve to the intake manifold. On the valve cover there's also a filter which has a hose that goes to the turbo inlet, though I have mine going to atmosphere as the turbo I swapped in doesn't have a port to route it to, so this is the only difference from the stock system.

Does anyone have any idea why the engine would build up enough pressure to launch that filter out of the valve cover and spray oil all over the engine bay? I'm not entirely sure what I can do here, aside from make the filter in the valve cover fit even more snugly so it doesn't launch out.

Thanks to anyone with advice!
 


franklin2

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Has it been driven very much since you rebuilt it? If the rings have not seated yet, boost may be making it's way into the crankcase. Do you see any smoke out of the tailpipe when you start it? If you do, it may need to be run a little more till the rings seat.

I rebuilt several engines and always had this problem. They would smoke and use a little bit of oil for the first month or so of use, and then clear up. I asked a old engine rebuilder what the problem could be, and he asked me when I am putting the engine together, and turning it over by hand with the pistons installed, do I hear this swishing noise when the pistons went up and down in the bore. I said yes. He said I was not getting the bores clean enough after honing. I thought I was, but the next engine I built I really cleaned the bores good. It took awhile. That engine never made that noise, and never used a drop of oil and no smoke since the first day I started it. Those old guys were smart.
 

scotts90ranger

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Been there, trying to remember what I did... I think I just put in a new PCV valve and let the engine break in more... The PCV valve is an important part of the equation as when the engine is under boost if the valve isn't closing it is pressurizing the crankcase. There for a while I ran the crank vent hose to a 3/8" hose into a quart oil jug as a makeshift catch can in camp or something (that ended up staying that way for like 3 years). I honestly don't remember where that hose goes to right now, I know I did something with it :)
 

ylidk

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It's been driven less than 100 miles, honestly probably closer to 50. I knew the engine would consume oil before the rings break in but I never really thought about the boost leaking past them and causing trouble. It's been on lots of shorter drives trying to nail down any issues that pop up before dailying it to get the engine properly broken in. Would it be a good/bad idea to purposely create a boost leak by disconnecting an intercooler pipe to prevent the engine from seeing boost while breaking it in? It's running a standalone ECU with speed density so it shouldn't affect the drivability at all. As for startup, it has been smoking some on start, but not a ton, and it's been cold enough that I was just chocking that up to the cold; just white smoke that didn't make me think it's burning oil. I'll keep driving it gingerly and replace that PCV valve and see where that gets me. Sounds like this isn't anything to worry too much about which is good. I'll top it off with some more break in oil and report back once I let it break in more and get the PCV valve swapped out. Thanks!
 

ylidk

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Replaced the PCV valve, but no change. Took it for a drive, oil was pushed up and out of the valve cover breather, same as before. I'll keep driving the truck at low loads to help the engine break in, if that is the issue here. A few questions about the PCV valve, in case the replacement I bought is also bad:

1) Are you supposed to be able to blow compressed air through the valve from either direction? I can blow through even on the small end that goes to the intake manifold, which is where the boost would be pushing from, so I think it might just be a DOA replacement.

2) Is the PCV valve intended to be installed exactly vertical in the engine bay? Currently it is installed horizontally, and I've noticed that when holding the valve horizontally, the check valve inside is at an angle, and with compressed air pushing it, it just jams itself at an angle and never seats properly. When vertical (large end up though) it rests on the spring evenly and usually seats properly. With the small side up (which would be the ideal install since the intake manifold is above the oil separator) It also seems to sit at an angle, though would usually (but not always) seat when being pushed by the pressure. Sometimes I had to jostle it to seat properly. In all orientations air still passes through both ways, though much more when it is jammed at an angle leaving an opening of course.
 

franklin2

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You could always just take the pcv valve out of the valve cover and let it suck engine compartment air while you took it for a test drive. See if the other breather pops out with the pcv just hanging there not in the engine.

You can help the rings break in faster. Find a road that is not very busy, get it warmed up, putt putt along and then nail the throttle and run it up full throttle till you get to the speed limit and then let off. Wait about 15 seconds or so, and do it again. Repeat this about 10 times in succession. Opening the throttle up puts a lot of pressure in the cylinder. This pressure gets behind the piston rings and pushes them out against the cylinder walls. This helps them break in faster. You do not want to over do it, hence the wind up and then let it rest,, wind it up and let it rest. You do not want to get the engine too hot and glaze the cylinders. But this pulsing power cycle will build pressure to push the rings out without over heating things.
 

ylidk

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You could always just take the pcv valve out of the valve cover
So I have a quick question about the proper setup of the PCV system based on this wording.

The replacement pcv valve has two ports on one side of the valve, this style here: https://www.autozone.com/emission-control-and-exhaust/pcv-valve/p/duralast-pcv-valve-pcv1210dl/830773_0_0?searchText=pcv+valve?vehicleId=1070901

On my engine, the valve did not have the dual ports, and only had one hose that goes into the intake manifold. The other side of the valve goes to the oil separator/block.

The valve cover doesn't have any connections to the pcv system, just a breather with a filter to atmosphere. This is where the pressure and oil are being pushed out of.

Is the valve cover supposed to have external connections to the pcv valve? It's entirely possible that my pcv valve setup just isn't correct.
 

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Regular PCV valve is never closed, no need for it to be on a normally aspirated engine
Its mostly closed at idle, high vacuum, then wide open when accelerating, low vacuum, to suck in the extra blow-by made at higher RPMs

It never "sees" positive pressure at the intake end

With boost you are forcing the PCV Valve open with positive pressure, that along with the extra blow-by just blows it off, so you are "boosting" the crankcase, lol
The breather is not big enough for the extra pressure, blow-by + boost

You can put a 1-way valve on the intake hose of PCV valve to block positive pressure, a check valve, during Boost

Excessive blow-bay during boost should go out the breather so I would install a catch can on that hose, or on both

Oil shouldn't come out the PCV valve hole, oil vapor will
Inside the valve cover there should be a plate under the PCV Valve hole, so there is no direct oil access, maybe a 1/2" gap between plate and valve cover, and there is often a filter, like a scotch bright mesh, between plate and hole

They do make PCV Valves for boost, basically a 1-way valve when there is positive pressure and PCV Valve without boost
 

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Can you post a pic of your setup?
 

scotts90ranger

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Most PCV valves come with an elbow with one or two connections on them, that's pressed onto a metal housing, all you have to do is pull that plastic elbow off the top...

I got a replacement PCV valve once for my turbo engine that had some holes around the perimeter on the big end, not sure on the purpose of that, I chose to install a random one that didn't have those that I found after I bought the replacement.

@alwaysFlOoReD On the Limas there's an oil separator in the crankcase behind the distributor hole with some mesh or something in it that has a 3/4" hose coming out the top, they run that hose forward and up a bit then stick a PCV in that then the PCV is what converts down to 3/8" hose then goes to a port on the bottom of the throttle body. Then they run a hose of some form (ranges from 1/4" to 3/8" usually out of the valve cover going to a fresh air source before the turbo or some people will put that to a catch can or whatnot...
 

ylidk

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Alright, sounds like I'll need to get a hose for the breather on the valve cover and route that to my catch can instead of the hose from the oil separator to intake. I have parts on order for that since the pressure actually popped the breather out of the valve cover while driving and I have not seen it since 🙃 I just picked up a generic filtered breather but it doesn't have a port to attach a hose to. The new set has a new grommet so hopefully everything fits more snugly into the valve cover this time. I will also get myself a one way check valve to install on the hose to the intake manifold alongside the PCV valve, or the boost rated PCV valve so that it is completely closed during boost and not pressurizing the crankcase to cause the breather to eject again.

Was the stock PCV valve on Ford's turbo engines not designed to do anything about boost getting into the crankcase? I grabbed the stock replacement for the turbocoupe, rather than the ranger PCV valve.

I can still go grab a picture if it will help, but the explanation by scotts90ranger is almost exactly how it is set up, aside from a catch can between the PCV valve and intake, and no hose from the valve cover breather to turbo inlet/catch can. Mine is just a filtered breather right now. A picture of the actual PCV hoses would be kind of hard to see what's going on since it's pretty cluttered down there.
 

scotts90ranger

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That stupid PCV with the holes in it was the turbo coupe one from the parts store, just get the one for a Ranger which should shut off. I wouldn't worry too much about boost rated anything and probably wouldn't run a check valve on the vent side as air should move both directions under normal conditions, not under high flow though...
 

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On the replacment PCV valves with two hose connections, that is just the aftermarket making universal parts. If you look at the new PCV valve with the dual hose connections, the smaller one will actually be plugged off with molded plastic. On applications that do not need this smaller hose, you just leave it plugged like they have it. Some engines used this smaller port for a canister purge, so in those applications you have to take side cutters and cut the molded plastic tip off so it's open and then stick the smaller hose in place.
 

ylidk

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Alright, I was out of town for a week and couldn't get everything together and tested until tonight. I installed a Vargas Turbo 100PSI rated check valve between the oil separator and throttle body, so that flow is allowed from the crankcase/oil separator to TB but not from TB to crankcase so it shouldn't be getting pressure through there. The stock PCV valve is still in line as well, but mainly just as an adapter for the hose size. Unfortunately, I grabbed the wrong size hose and adapters for the valve cover, so it still vents to atmosphere until I can route it to the catch can. That being said, that would only catch the oil being shot out and not actually fix the over-pressure issue I am seeing.

After my test drive: Nothing changed. Still getting oil blowing out of the valve cover, even when the PCV can't be providing that boost. Must be blow by then? That seems like an insane amount of blow by to cause this much pressure and this much oil to shoot out. I tried multiple slow runs ramping up to help break in the rings but there doesn't seem to be any improvement. It is during these slow runs that at higher RPM's the oil shoots out. Really at a loss. At the rate this oil is coming out I'll need to empty the catch can every few miles and top off the engine oil to avoid it running dry.

Pictures below of a UV light showing the oil shot out of the valve cover adapter and onto my brake booster, though it is getting all over the engine bay.

signal-2024-03-03-185244_002.jpeg
signal-2024-03-03-185200_002.jpeg
 

ylidk

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Update after getting the rest of the hose/adapters for the valve cover to catch can line - oil is still being blown out of the valve cover through that hole. I purchased and installed the stock replacement elbow and rubber gasket for this engine, yet oil is being forced out from between the two. I'm sure some is making its way to the catch can, but enough is escaping that I have noticed no significant decrease in smoke from oil being burned on the exhaust, so it appears that the check valve and catch can setup was unsuccessful, with no notable difference. In the image below you can see oil between the elbow and gasket, as well as between the gasket and valve cover.

signal-2024-03-04-175954.jpeg
 

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