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PCV valve replacement, quick question or two  

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NottaMiata
(@nottamiata)
Honorable Member

Hi.

It is well past time to replace the PCV valve in The Frog. Maybe. But if you don't know if you still have the original part from '03, why not just do it?  I have a new OE part on hand. 

Took some time to do a little research first, wandered around the interwebz, read some some 16-year old posts from one of our members about turbo kits, catch cans, ET Performance's Krank Vent, continuous vacuum in the crankcase, etc.  Good stuff, but maybe a bit too much for The Frog to get carried away with a catch cat right now. Catch can will not do much good to help me with my "looming" pre-cat disintegration or some wet-brakes incident that may or may not have been corrected with a simple bleed and proper T-Juice Red in the lines.

@dev, why did you go back to just replacing the PCV valve yearly and calling it good?  I understand the utter simplicity part of the appeal, and I put plenty of value on that, but is that all? Don't all these low-tech stock valves leave slug-trails of crankcase foulness through the intake?  Did people stop caring at some point?  A catch can seems pretty low-tech and simple too, and it's bound to be healthier than re-burning all the crankcase stank.

Then I watched a video of a silly young man using teflon pipe thread tape to seal the new PCV he was installing. I suppose he has never removed and replaced a pipe tape seal.  But wait, those indestructible, tenacious little teflon-plastic strings are just fine floating around inside the crankcase, right?  I just worry too much? I'm just a big ol' over-thinker? I think I'll pass on the tape, just out of caution.

 

I notice there is a nice thin ring of some red thread locker-looking stuff on the threads of the new PCV I have; will this be adequate?  I realize that this could be a ridiculously "well, duh" question, but I just want to be sure, because sometimes this sort of thing is just CYA half-assery on the part of the mfr. But, along the same lines as the pipe tape, I also wonder if the practice of adding just a bit more, "just to be sure" is a dumb idea too. I wasn't considering it, unless of course, it's a *good* idea. 

See? I'm leaning heavily toward thinking it's adequate and correct as is, unless the valve is removed and replaced during the install for some reason, in which case it needs a fresh, *thin* coating on the threads again with a bit of care not to introduce crumbs into The Frog's spleen.  Is thread locker better here than something like copper grease?  This is all just so I know; this is the difference between just following a process and understanding why you are following a process; the very foundation of Skill/Talent/Experience, and eventually Art.  I'll never make it as far as Artistic, but a bit of intuition about what to do and when to do it (and when to just take a step back) really goes a long way.

So, "just turn it!", or do add some thread locker, and what about the copper grease instead?  I'll check out the hose too.  Still sniffing for that unlikely-but-not-impossible vacuum leak that's probably not there and not causing my sporadic braking issues.

Also, I know the crankcase cover material is soft, yes?  So I'm betting that torque it to "gorilla" is probably unwise here like it is almost everywhere... is there a torque spec on this thing that somebody could share, please?  Wait, let me guess: it's gonna be a low value... something like 15 to 18 ft/lbs?

 

TIA

🐸, 2003, Electric Green Mica, not enough mods

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Posted : March 7, 2020 7:27 am
dev
 dev
(@dev)
Just a member. Moderator

 The best thing you did so far is use an OE part but you are overthinking this. 

 Just remove the old PCV valve and screw on the new one. Tighten it to where it is reasonably tight. That means where its not so easy to turn but don't gorilla it.  Do not add anything extra its not coming off.  If you want to do something extra buy a new OE clamp for the PCV valve hose. 

 As far as catch cans it is my opinion you don't need them at all. As to their effectiveness if they help or hurt its a wash. Millions of Toyota cars and trucks don't have catch cans and they all do fine in this area because the blowby gasses get burned up and they dont cause any kind of long term valve issues as long as you use gas with the mandated levels of detergency.  Valves remain clean and the engine will run as it should for many thousands of miles without any evidence that this is a problem in a well designed engine.  Problems like this can be found in poor designs from the Germans with the direct injection systems but not Toyotas. 

 The reason why I dont have a catch can is simple because I like simplicity of design and I do not need anything extra in the engine bay compartment to complicate it further. The more stuff and connections leads to more points of failures and that is precisely why I do not run an oil cooler because I monitor my temps instead. 

 People tend to add more than they need without any bases of logic. First you need to have a problem before you can solve it. Theoretical crap is just that, it will get you into trouble with a lot of unknowns.  There is a guy that was running 20w-60 oil in his 2zz Spyder which spun a bearing on the track. Could not understand why when he was running thicker oil. Its these kind of mistakes that happens more often when you overthink the engineers. There is a nuance to everything but sadly people only see in black and white and let their bias get in the way because its cool to do something for the sake of it. 

 

 

 

ReplyQuote
Posted : March 7, 2020 9:03 am
dblotii
(@dblotii)
Trusted Member

The best pipe-thread sealant for automotive use is Loctite or Permatex PST (Pipe-Sealant with Teflon).  It is an anaerobic (like Loctite thread-locker) and is designed for sealing threads.  It is also a weak thread-locker.

Like Dev says, keep the PCV functioning.  The fumes that are directed to the intake manifold have a very high concentration of Hydrocarbons which burn (and make power) very nicely in the engine.  Much better than polluting by venting to atmosphere.  PCV systems were the very first form of emissions control in engines.  The other reason for keeping the PCV system intact is that a properly functioning PCV system greatly slows down the deterioration rate of the oil in the crankcase.  If you want to use a catch-can, keep the hose connection points intact.

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Posted : March 7, 2020 10:35 am
dev
 dev
(@dev)
Just a member. Moderator
Posted by: @dblotii

The best pipe-thread sealant for automotive use is Loctite or Permatex PST (Pipe-Sealant with Teflon).  It is an anaerobic (like Loctite thread-locker) and is designed for sealing threads.  It is also a weak thread-locker.

Like Dev says, keep the PCV functioning.  The fumes that are directed to the intake manifold have a very high concentration of Hydrocarbons which burn (and make power) very nicely in the engine.  Much better than polluting by venting to atmosphere.  PCV systems were the very first form of emissions control in engines.  The other reason for keeping the PCV system intact is that a properly functioning PCV system greatly slows down the deterioration rate of the oil in the crankcase.  If you want to use a catch-can, keep the hose connection points intact.

 Thanks for the tip on the Teflon pipe Sealant as I could find uses for it in my coffee hobby with some of the plumbing that can develop  leaks from time to time with its larger thread spacing on soft brass fittings.  

 In regards to the OEM Toyota PCV it already comes with a pink teflon coating.  Toyota is really good with stuff like this when it comes to attention to details and its the only manufacture I know where the OEM parts are very reasonable. For their Luxury brand that shares the same parts its pretty amazing the difference between the Germans which is just outrageous. 

 

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Posted : March 7, 2020 10:54 am
marsrock7
(@marsrock7)
Reputable Member

Side anecdote: I did the cheap krankvent system before my crank scraper install (and subsequent oil change) and I like the results. It was done with OEM Supra PCV valves installed inline in the breather and PCV hoses, leaving the (newish) PCV valve in place. A little more clicky noise at idle but it's not hard to get used to. Can't hear it in the cabin. I've driven about 4000 (hard) miles on the current oil and it appears I am losing significantly less oil than before these two mods. My oil is also still a nice amber color, which I am surprised by. Usually at this mileage the oil is darkened. Can't say whether this is an effect of the negative crankcase pressure, the scraper reducing oil aeration, or a combination of the two. Either way I'm happy with what's happening in my oiling system right now.

ReplyQuote
Posted : March 7, 2020 11:36 am
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