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PCV and oil leaks

mgtf328

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I know, sorry PCV's AGAIN!!!

I'm wondering how effective fitting a PCV will be in eliminating the small oil leaks I have from the rear main bearing and the timing cover. I'm also thinking it may help reduce the puff of blue smoke I get when starting the car up from cold.

However,
I am concerned that pulling a depression in the crankcase, which I've read can be up to several psi, might have some detrimental effect on the oil distribution
, especially to the rear and front crank bearings. Has anyone got any thoughts or experience of this?

It seems to me that fitting a smaller valve such as a Ford 4 cylinder PCV from a
Pinto engine might
pull a lower depression than say fitting one from a larger 6 or even 8 cylinder engine. What type of valve have others used? Also I may experiment with fitting a restrictor in the line between the breather and the PCV. I'll ram a short piece of steel rod with a small hole drilled in it into the pipe so I can experiment with controlling the flow/pressure.
Any comments would be appreciated.
AJ
 
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AJ
i used the PCV valve suggested on the forum and i believe that came from a BCS kit. i got the NAPA version of the same one.

However i did feel i had way too much vacuum in the engine. so i controlled that with a filtered fresh air intake and a small paint gun valve from HF.

a couple of things i read:
1) it is good for an engine to have fresh air vented in to the crankcase. it helps to remove harmful vapors from the oil and blow-by.
2) the amount of vacuum in the crankcase should be about 4-6 inches of water. (about 1/2" of HG)

PCV systems, after the first couple of years, went to a filtered vented system. Maybe to control the vaccum?

Since there is not a PCV valve designed for our cars, i am not sure you will ever find one that gives the proper amount of vacuum. And there are lots of variables. how well is your engine sealed? how much blow-by do you get? Etc. Plus no one on this forum or anywhere i have read on AH cars has said what that vacuum should be. i got the info above from a tech article on a hot rod site.

by adding the vent and controlling the vacuum with the air valve, i could set my vacuum to just under 1" of HG. (i do not have a water gauge) after setting the vacuum, i checked and it does not change at any speed or in higher vacuum situations. it stays consistent at just under 1". i felt that meant the PCV valve was working as it should.

i first used a brass fitting in the vent line to the freash air filter trying to control the vacuum. after drilling it a couple of times to get close to where i wanted, i saw the valve at HF for a couple of bucks and it has worked better. i put a vac gauge on the line and then just adjust the valve.

i pull my vacuum from the valve cover. it runs from there over to an oil catch can and then to the PCV valve and on to the intake manifold. i use the side port at the tappet cover for my air intake. the verticle vent tube from the side cover to the valve cover is still there for looks but it is blocked with a rubber plug. the plug is actually stuck in the metal T at the valve cover. this way i can disconnect the verticle pipe at the top, hook my vac gauge there to recheck my vacuum at any time.

Does it help with oil leaks? i can't really say for sure. i get oil out the bell hole... from my gearbox. i also installed a rear main seal kit when rebuilding the engine. the engine did not have any oil leaks from the front before i started this project. So i ended up making catch pans that fit under the bell hole and the rear of the gearbox to keep oil off the floor.

good thing is i can pull this PCV system back out in a few minutes if i decide it is not worth it at some point.

here is a pic of the vented side and the valve. if you look close in the bottom right of the picture, you can see my filter. it is tucked away behind the brace.
fullsizeoutput_2d8.jpg

here is a pic from up top. i have a tri-carb so the vac line comes in to the front intake. the PCV valve is behind the valve cover. the hose going to the back carb has a "T" in it. the side to the carb is plugged and the back of the T goes to the oil catch can on the left.
fullsizeoutput_2db.jpg
 

steveg

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I'm also using a PCV, but I think the primary defense against oil leaks is sealing up the bottom end. My car only leaks a drop from the front bearing. No leaks from the timing cover and rear main and seal. Used Permatex Aviation Form a Gasket as the glue for the gaskets, with Hylomar Universal Blue on the side that releases. I would glue the gasket to the part and let it set overnight with the bolts in the holes for alignment. In the morning it would be stuck but still moveable.

Timing cover: glued gasket to timing cover. BCS sells a u-shaped reinforcing plate for the bolts on the lower half. It's about 1/16" thick. I used it as a guide to cut an additional reinforcer from 1/8" x 2" steel. Then bolted up with longer bolts and the oblong washers.

Tappet covers: Tom's Toys rubber gaskets glued to tappet covers.

Front and rear main bearing caps, bottom rectangular depression usually occupied by cork strip: filled with Permatex Ultra Black. Engine builder had filled the round plugs with silicone in place of the felt "cigarettes".

Pan (Aluminum): Tom's rubber gasket, glued to pan, bolted with sealing washers. Bolts and washers gooped with Form a Gasket.

Valve cover (Aluminum): cork gasket glued to valve cover. Here I've found weatherstrip adhesive superior to Form a Gasket for holding the gasket in place on the flat surface of the valve cover. I haven't been able to make the red silicone rubber gaskets work with the aluminum valve cover, though they seem to do fine on the stock covers.
 
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Bob_Spidell

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I've had a PCV 'system' for years on my BJ8; originally the BCS design and parts. When I had the engine rebuilt a couple years ago the mechanic upgraded the system (I know y'all seen this pic before, but the OP apparently has not):

IMG_0418.jpg

Steve (above) has an even more sophisticated rig, but he has an aftermarket manifold. I think the system gets its 'fresh' air entirely through the rear main bearing (though how fresh the air is is debatable). I haven't checked the bottom end since the rebuild, but I have over 10K miles on the engine with no apparent issues, and I probably put over 60K miles on the previous 'Nock Design' and my crankshaft still mic'd STD (at 200K+ miles). I gave the mechanic a rear main seal to install, but he said the PCV was the way to go, and he appears to be correct. When I installed the original system oil consumption was cut almost exactly in half on long trips (from 1qt/1K miles to 1qt/2K miles).

I was under the car yesterday, and the hole in the bottom of the bell housing was dry as a bone.
 

steveg

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Bob - thanks for the compliment. My system, however, does the same thing yours does - it takes vacuum equally from both carburetors. I my case from the middle of the balance pipe. The PCV valve is the one called out by Norm Nock in his book. Delco 727C (IIRC from a '70s Gremlin 6 cyl).

IntakeWithPCV.jpg
 
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RAC68

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Hi Guys,

I have come close to installing a PCV and even created an oil catch can for the installation. However, due to the lack of published information I could find on valve specifications (designed for and selected by specific car and engine) or the amount of vacuum appropriate in the bottom end of an engine, I decided not to continue.

I must admit I found Drone Dog's post most enlightening and am having second thoughts on continuing a PCV installation. He presented a specification as to what internal engine vacuum level is appropriate to maintain in operation and, most importantly, a method to monitor and control that vacuum. As a result of his vacuum monitoring and management approach, the selection of the commonly used PCV becomes less of a leap of faith and can be tuned to the internal value he identified (4"-6" of water). When added to the method of evenly drawing vacuum posted by Bob and Steve, and we have a much better and we seem to be evolving a much more enlightened approach to PCV implementation.

My last questions are:
1. As a common starting point, what PCV is Drone Dog using and what was it maintaining before air intake valve adjustment?
2. Is there any performance benefit to a PCV installation?

Keep in mind that, if the answer to question 2 is none, we are talking about performing a PCV implementation (and added complexity) to eliminate a few oil drops on the garage floor when a piece of strategically placed cardboard could, for some, satisfy as well.

Just my thoughts,
Ray(64BJ8P1)
 
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Ray
i used a NAPA PCV valve. it was the cross-ref to the one listed by BCS. i looked back thru my invoices but can't find the PCV one. i know i posted it here in an earlier thread on PCV valves. you can probably do a better search than myself.

my vacuum without any air inlet was too high. once i got my dipstick sealed properly, it was running up around 10" HG. at 9" HG, it would cause the oil pan to pop. So i added an air inlet. the only reason i went with 1" of HG is that i felt it was the lowest i could read on my gauge. i tried find a water gauge but no luck at a reasonable price. i believe 2" of HG is equal to 27" of H2O?

Now my engine was just rebuilt about 1200 miles ago. All new seals and gaskets. also all of them using glue and Hylomar. etc. i also used gapless rings which probably cut down on blow-by.

my concern was too much vacuum would pull dirt in the engine seals. just like positive pressure can push oil out. the problem was i could not find any info on what the vacuum should be. i searched all sorts of websites. (keep in mind i am not the best searcher in the world) i finally found this tech article on a hot rod website somewhere. i did not save it but it made pretty good sense. And it was the only place i found an actual number to go by. is it the absolute truth? who knows? best number for this engine? Can't say.

i also read numerous articles on the PCV system and the change to a vented system. that is an easy google search.

Does it help the engine performance as far as power? i did not read that anywhere. i believe the system was developed to help with air pollution and to cut back on oil leaking in to the environment. after a couple of years they went to a vented system. the added benefit to the vented system was that fresh air helped to remove bad gasses from the crankcase. cuts back on sludge, gunk, and moisture build up.... thus wear on engine parts. Also the vented system would allow for any positive pressure created in the engine. Thus you could seal off the oil cap and the dipstick and cut down on dirt being pulled in to the engine there. i also read the vaccum can actually help to expand the rings cutting down on blow-by and oil burning.

Of course a lot of these engines went pretty far on the original design so is it worth it?

my hope was it would help keep the oil in the engine. does it help? i can't say for sure. as i mentioned above, it is a rebuilt engine. didn't really have a good handle oil leaks before i started this project. i get oil out the bell vent but i feel most.. if not all... of the oil there is from the gearbox. i have not run the engine oil long enough for it to get black and be able to tell. even now, if i change once a year, it probably won't have much over a 1000 miles on the oil. current oil has been in about 300+ miles. it has not moved even a little on the dipstick. (i know, i need to drive the car more)

as far as the cardboard goes.... i can't carry it with me and i don't want to drip oil in another person's driveway. So i built a couple drip pans. another fun project. i like those.

Sorry this got long. when i used to work, a buddy of mine said he would never open an email from me on Friday. he said he wanted to take the weekend off.
 
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mgtf328

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Guys, thanks for all your contributions. I got interested in PCV’s because I recently fitted a catch tank (with a built in sintered filter) in the line from the tappet vent to the air filter. I was trying to stop contaminants from fouling the plugs. It didn’t work, dah, the carbs were too rich! But it did result in my rocker cover gasket leaking oil, I think the sintered filter was too fine blocking the flow. So I removed it. To me this indicated that the crankcase is operating under a positive pressure and all I succeeded in doing was to increase it. So maybe this is why my rear oil seal leaks! PCV!!!
So I began to wonder if anyone has gathered any more operating experience with PCV’s before I jump in. Drone Dog, I think you and I are on the same page. The trick is to control the pressure in the crankcase so we drag it down just far enough to keep the oil in. I tried to do this on my MG by inserting a restriction in the pipeline to the PCV. I think your solution is elegant by the way but I’d like to know what you used to measure 1” Hg vacuum!
I wondered what would happen changing the crankcase pressure from a relatively small +ve to a large -ve pressure. How much would it change and what will this do to the conditions under which the oil pump operates? I seem to remember that gear pumps don’t much like negative suction pressures as it tends to promote fluid slip back through the gears reducing the flow. Is the reduction in leakage a result of the pump producing less flow? Probably not but I guess the pressure change must be having some effect, but what?
Before I make what might be an expensive mistake I’m going to try to measure the pressure before and after fitting the PCV then I need to find the pump curve to see what effect it will have. A winter project I think.
Thanks again
AJ
 

John Turney

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One can make an inexpensive vacuum/pressure gauge that measures in inches of water with a loop of clear vinyl tubing with water in it. If you want to see it easier, add a drop or two of food coloring.
 
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Hilarious. Even using a regulator. My guess is these engines don't last long enough to plug up the lines.
Used to get the steel lines from manifold vacuum to PCV, clamp them in a vise, torch and air nozzle, once you got the plug hot enough, it was a blowtorch out the end. Did them in shops all the time.
Originally oil fill cap was big, vented, filled with..steel wool. Those would get gunked up, but for sure solvent wash each oil change
There never was a spec on amount of vacuum. CARB simply wanted crankcase fumes out of the atmosphere. When someome thought maybe fumes could go back out the oil fill vent, those literally got outlawed (but grandfathered) and the vent was on the venturi side of the air filter element.
Before PCV we had road draught tubes. Baloney cut to increase draught at speed. And our mains always leaked...they were supposed to. Rope seals, if no oil, burned out.
So, seal it up, adjust your regulator, and something goes haywire on a long road trip....and you have 19 inches in the sump......fun.
Kinda like the guy I used to know who told folks to monitor coolant pressure to keep from overheating.
 
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AJ
i put a vacuum gauge on the verticle pipe from the side cover. i pull the pipe out of the rubber hose and attach the gauge at the top. You can see my rubber "T" at the bottom in the previous post.

at first i put it over the dipstick tube and measured from there. i got the same reading but i wondered if my dipstick tube might also leak a little. so i decided to put the dipstick in and measure from the pipe. keep in mind my metal "T" at the top of the valve cover is plugged on the pipe side so all the vacuum is pulled from the valve cover.

if the negative pressure had an effect on the oil pump, would you not see a drop in oil pressure?

i believe the early closed systems used to leave the dipstick unsealed and the oil fill cap was vented. if you did not do this, you pulled all the air in by the seals.

Again i do not know that the 6" of H2O is the gospel. it is just the only number i ever found. i do not have enough experience as a mechanic, especially with AH engines, to have a feel for these things.

IMG_0763.jpgIMG_0772.jpg

The one thing about the valve i used vs the fitting i had in the line at the begginning. the valve has a little whistle to it. when i shut the car off, for about 2 seconds, you can hear air still going thru the valve. if i completely open the valve my gauge will not read a vacuum.
 

Bob_Spidell

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Interesting. But, this ...

"An internal check valve within a housing is held closed by a spring when no engine vacuum is present. As manifold vacuum signal overcomes that spring tension, the check valve opens and the engine ingests (and consumes) the blowby vapor within the crankcase. The amount of airflow passing through the PCV valve varies with engine vacuum, which is directly tied to engine load."

... is the opposite of how I thought PCV valves worked. After all, engine vacuum is greatest at idle with the throttles closed, or all but closed, and you want the valve to be closed so it doesn't present a large vacuum leak to the engine (and very poor running). Did I have this wrong all these years?
 

steveg

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From their testing, materials and videos, it's clear they understand exactly how PCV valves normally work (even if I don't). There's a market for their adjustable valves for hopped up engines and those like ours that never came with a PCV. Most tuners are guessing or trying out a lot of different valves. Evidently all kinds of issues can result from a PCV that flows either too much or not enough air for the individual engine.

Our PCVs aren't normal, however. A typical non-Healey installation has a minimum 3/4" air inlet from the air cleaner to one of the valve covers. So there's a potential for a large amount of air leaning out the mixture if the PCV admits too much below the carburetor. IMO we can't have that problem because the amount of air admitted is limited by the rear main and dipstick.

With my dual AFR gauges, I'm not seeing any bad spikes of leanness, but may think about adding one of these valves. The inline-adapter version is $149.

I'll be talking to them about the Healey setup.
 

Lin

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When BDCVG posted the link, I knew it would not be long before Steveg would say, ‘I think I will try one!” He is always the one willing to go where no man has gone before! Looking forward to hearing the results. Thanks, Steve. 😱🤞🏻
 

steveg

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Spoke with Gene Wagner of M/EWagner. He said our setups pulling the air through the rear bearing are not good - I tend to agree the concept doesn't feel right. There always needs to be a filtered air inlet to the valve cover or crankcase. Then the Dual Flow PCV is used to valve the air at idle and running.

I'm thinking of installing a bulkhead barb fitting in the side of my valve cover and running a hose from the front air cleaner. I'd fire up my old stock cover for this before cutting a hole in the Ray Juncal cover.

screenshot.1873.jpg


Another possibility would be to install the barb fitting in the middle or front tappet covers with one of the small K&N filters on it.
 
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See my post and picture above. i used a "T" off the rear side tappet cover. the hole is already there. i only used the "T" so i could keep the side pipe look. you could run the filter right off the hole if you did not want to keep that side pipe.

i also thought of getting another rear tappet cover and using it for the middle cover and just attach my filter there. then leave my side pipe alone (but plugged). i think i found the rear tappet covers were expensive. So i went with a "T".

My thought on the venting of the valve cover. i think this probably works well on a V8 or any V type engine. you pull from one valve cover and have the filtered air come in the other. then the air moves thru the crankcase. on a straight engine (ours a straight 6) it seems the air would only move thru the upper part of the engine. that is the reason i went with the tappet cover.

i was originally going to run the vacuum side out of the side tappet cover and let the air intake side just come from the valve cover. then i would have left my hose from the valve cover T to the rear carb and let the rear carb breather act as my filter. this set up sure looked the cleanest. but someone pointed out that i would probably pull more oil out of the engine from the side cover. good point! so i changed mine around. The valve cover also has a baffle inside to keep oil from being sucked directly out.

i have only run a few hundred miles on my car this summer. but so far i have not had any oil to drain out of the catch can. i want to run it a bit further to be sure there is not any oil being pulled. if i don't get any oil after another year, i may eliminate my catch can and go back to connecting the PCV line direct to the front port from the valve cover T. Again just looks cleaner.
 

steveg

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DD - thank you for your insights.

I agree about the air intake on the valve cover being a bad idea for a straight 6. Besides, I hate to drill holes in the valve cover. :mad:

Installing one of the little K&Ns on a bulkhead barb fitting under the alternator on the front tappet cover would be easy to do and could be plugged inconspicuously later if desired.

I'd experiment with plugging the left side of the tee to disable the side pipe, forcing the ventilation up from the crankcase, through the head and valve cover, through the PCV and into the intake manifold.

After Deadwood, will move forward with this.
 
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mgtf328

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I'm loosing the plot now. I was concerned that fitting a PCV would have a detrimental effect on oil supply to the rear bearing and it's nice when someone with a little knowledge agrees. Fitting a fresh air intake will only allow us to control the vacuum if we go about it properly. Presumably the vacuum will still be there otherwise there's no point in fitting the PCV and as long as there's a vacuum in the crankcase air will still be pulled in through the seals. So I'm back to my original question. What's the point it fitting a PCV?
AJ
 
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