Advice on PCV setup

martymil

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The vacuum realief valve will fix the issue but you have to adjust it and possibly trim the spring, you will have to use a vacuum gauge on the valve cover to see how much your inhg your pulling, you should set it to 5 to 6 but like most Ive seen that start to whistle is around 2 to 3 stock is less than 0.5 inhg
 

Torgus

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Nov 6, 2016
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The VTT vac relief is either a knock off(most likely) or private labeled from Moroso. instructions and product is identical. Moroso make a number of versions NPT AN etc.

There are a number of these on the market: https://www.gzmotorsports.com/relief-valves.html & https://www.amazon.com/JEGS-23630-Adjustable-Vacuum-Relief/dp/B078WHWPMY for example.

I agree with @Cruizinmax I think you are pulling too much vac.
 
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Tzaks

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May 30, 2019
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I will wait for my adaptor pipe to arrive and fit the VTT vacuum relief valve straight to the head.
Will update soon!
 

Cruizinmax

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The vacuum relief will solve your issue. One way you can test prior is open you oil cap a little when it's whistling. Just enough to allow air in and see if it stops.

Also I don't believe the vacuum relief valve is appropriate for a street car that sees very many miles. You are essentially letting unfiltered air in your crankcase along with all the dust and dirt it contains.
 

Tzaks

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May 30, 2019
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This is what I used. It came here about an hour ago. Its an10 to an10 with a switchable extension in between. Used a copper o-ring between the block and the fitting to seal properly.

I'm still pulling too much vacuum, the engine has occasional hiccups and it even turned off once. I removed the VTT vacuum relief valve to allow more flow inside the crankcase, it still runs a bit rough, it's intermittent but I can feel that it doesn't have that linear smoothness.

Does it matter where I'm installing the one-way check valve for the low side? Saw people using both (between crankcase and OCC) / (between OCC and Intake manifold) with good results.
169087300_457907838759357_3007992891452081920_n.jpg
 

Tzaks

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Can probably fit a small filter where the holes are, after I solve my problem I will try to DIY something and update.

I will remove the restriction on the low side hose and run another test.
 

Tzaks

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May 30, 2019
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I did a few more tests that I will outline and describe the best I can below:

1. Test setup one
* I blocked the pipe from the intake manifold but still left the Nylon lines in. This setup works fine or at least that's the first impression but when checking vacuum in the crankcase, vacuum seems be non-existent. The end of this hose is blocked.
1618076131748.png


2. Test setup two
* I removed the restriction, there's way too much vacuum applied to the crankcase which results in a whistling sound as air passes through the VC gasket.

3. Test setup three
* I installed a nut with a very small opening on the hose between the OCC and the Intake Manifold. Used a clamp on the outside of the hose so no air can go around this nut, only through. This improved the situation however, the vacuum applied to the crankcase is still too much. Please see picture below, USB stick for size reference.
1618076310089.png



Conclusion:
It seems that even the smallest opening will still allow too much flow and create a lot of vacuum in the crankcase. I believe that due to the spring in the PCV valve and the way the valve is designed, it acts as an airflow restriction because of the path the air has to take and no simple hole can achieve that.

The VTT Vacuum relief valve seems to be doing precisely nothing. Not sure if it's not allowing enough flow through inside the engine or if the spring is too hard. According to their website, they provide 3 shims with it.
No shim = 10inHG
1 shim = 12
2 = 14
3 = 16

From my testing, I can't tell if it's opening or not, tried with no shims, or with 1 shim. If I blow through it with some mouth action, it does open so perhaps it's not letting enough airflow through. The weather over here is crap as always and it's too windy to actually tell if it's sucking anything else than my energy. I will try with a vape pen to blow some smoke on it when it's not as windy to see if it's actually doing anything.

Action:
I have purchased a 2JZ PCV valve which according to @Panzerfaust and his post it should be a perfect fit for the an8 hose. Will update afterwards.
 
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martymil

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If your pulling to much vacuum with shims removed you need a pair of really sharp side cutters and trim the spring in the vacuum relief valve half a turn of the coil at a time to reach your desired amount of vacuum.

So for if the coil has 5 turns trim to 4.5 turns, if you go a little to much don't worry as you can use the shims to bring it back up.

Be patient and don't trim to much first go and reinstall and test after every trim.
 
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