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Discussion Starter #1
Setup:
DOHC ZC (fresh rebuild)
JRSC (from D16A6 kit running 5.5Psi)

The motor is a fresh rebuild, done by myself and a friend, machine work by a professional. First summer it was back together (2013), had a lot of oil burning issues. Had the machine shop redo the guides on the head, and that cleared up most of it.

Now this season (2014) I still have SOME oil issues. Mainly happening after a section of foot off throttle deceleration, usually on a downhill. The longer I say off the gas and let the engine slow down the car, the more oil I get out the tailpipe ONLY AFTER I get back on the throttle. I don’t see very much under hard acceleration in other conditions. (there is a bit, some of the time).

Rebuild including rings now has about 2k KMs on it (1250 miles).

So my question is this. Does this sound like the rings simply didn't seat properly and I will need to do them again? The reason I ask is I have had some people telling me it has to do with the boost, and that I’m not running any kind of catch can setup (just the factory PCV etc.). I find this hard to believe, but thought I would ask. Is it possible this could be solved by a catch can, or it just a ring issue and that's the only way to solve it?

Any constructive thoughts are appreciated.
 

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The pcv is a good start and yes you need to run a catch can setup. Chances are you have way too much crank case pressure and could, or have already damaged your valve seals. I'm also wondering if the bypass valve is sticking or maybe stuck closed? This would cause a boost condition (although minimal) even on decel.
 

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Valve stem seals. Make sure they are the right diameter.
I have to agree with beav here.

Your getting oil drawn past the valve seals/guides, because while decelerating, especially in gear, your engine is producing its maximum vacuum, causing the issue. So when you hit the gas your burning the oil that has been drawn past the seals/guide.
 

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Discussion Starter #5
The pcv is a good start and yes you need to run a catch can setup. Chances are you have way too much crank case pressure and could, or have already damaged your valve seals. I'm also wondering if the bypass valve is sticking or maybe stuck closed? This would cause a boost condition (although minimal) even on decel.
So bare with me, as I’m not fully versed on catch cans theory.

My understanding of a catch can setup, is it just stops any oil vapor from recirculating into the intake manifold like it would in the factory setup.

Is the idea that because it’s no longer a “sealed” system (from factory black box at the back of the block, up hose through PCV valve then into intake manifold) the reason a catch can would remove crank case pressure?

Can you try and explain why crank case pressure would be giving me the above oil burn issues?

Last, could I test this by basically just venting to atmosphere from the black box on the back of the block for a test run down a hill, or is there something else I am missing?

I have checked and changed the PCV valve just thinking that might be it, but no change.
 

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Discussion Starter #6
Valve stem seals. Make sure they are the right diameter.
I have to agree with beav here.

Your getting oil drawn past the valve seals/guides, because while decelerating, especially in gear, your engine is producing its maximum vacuum, causing the issue. So when you hit the gas your burning the oil that has been drawn past the seals/guide.
I have actually replaced the valve seals 3 times over the last 2 seasons of doing this setup. I am sure they are the correct size, however are you saying that under deceleration vacuum I'm pulling oil down from the head?

Lets say for now the seals are good, or at least were when they were installed. What do I address next so it doesn't happen again, or may solve the current issue?
 

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the artist formerly known as drexelstudent11
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you've replaced the seals 3 times in 2 years? have you replaced the valve guides?

bad guides will wear out a set of seals very quickly
 

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I had/have the same problem on my d16y7. This motor would seriously crop dust after a long steep downhill stretch with engine braking, it ended up burning a valve a few months ago. I did a cheap-o rebuild on the head that included new exhaust valves, all new valve seals, all rubber gaskets, oem head gasket and head bolts, and a new pcv valve. After doing all of that the damn motor still burns oil! The motor still runs well it just burns through a quart very quickly, almost seems to burn faster now. I suspect the rings to be bad, but I refuse to dump more money into the y7 so I just bought a y8 to swap.
 

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Discussion Starter #11
you've replaced the seals 3 times in 2 years? have you replaced the valve guides?

bad guides will wear out a set of seals very quickly
Valve GUIDES....
1st change of seals, during rebuild process.

When I first got the motor together and put it in the car in 2013, it burnt a ton of oil. After some leak down tests and finally pulling the head after letting it sit for a while, I found a puddle of oil on top of the cylinders. I changed the seals then, that was the 2nd time.

No change, still burnt lots of oil, so this last winter the head went back to the machine shop and the guides were replaced. They replaced the seals again when the guides were redone. That cleaned up MOST of the issue, but still having the burn after throttle off deceleration as described above.

I'm doing some trailing arm work right now, but when I'm done Ill try venting the PCV box to atmosphere just to see if it changes anything on a down hill run. If not, then I guess its back to the machine shop to investigate the head, again.
 

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Why not just run a simple leak down test and see if the rings or valves are sealing like they should.

If they are then its to much positive crank case pressure pushing oil past the seals while in vacuum. :bigok:
 

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Discussion Starter #13
Why not just run a simple leak down test and see if the rings or valves are sealing like they should.

If they are then its to much positive crank case pressure pushing oil past the seals while in vacuum. :bigok:
Last leak down test I did was before the head was rebuilt (again), but it did show the rings seemed to be seating okay.

So lets say that what your saying is correct "If they are then its to much positive crank case pressure pushing oil past the seals while in vacuum".

If this was the case, should I expect to see a difference by venting the black box to atmosphere? Or what do I do to correct this issue?
 

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Drill out the stock pcv and install a tube to it and point it to the ground.. its called a draft style pcv system.. and cars used this setup for years before emissions control.

This way you don't have to even buy a catch can system to find out if its getting to much positive crank case pressure... I would run a breather on the valve cover also.

I run a ghetto style catch can drilled out pcv setup from my black box.. witch is being changed to a drain back system when i decide to turn the boost up. My setup is runing 10 psi and i never have anything in the catch can, just a few drops of water mostly.. all its doiing is releasing crank case pressure under boost so you don't stress the seals.. from not running a open PVC system on a boosted motor.. you might have done some damage to the valve seals..

I would do a leak down test just to be sure, it takes 5 min. BUT your not wasting your time installing an open pcv system on your motor so get to work and report back with the results otherwise ima neg rep your ass lol just kidding GL
 

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you've replaced the seals 3 times in 2 years? have you replaced the valve guides?

bad guides will wear out a set of seals very quickly
Valve GUIDES....
This ^^

No matter how new the seals are, if the guides are fuct, then theres no way the seals will be able to do theyre job. I would look to a different machine shop if youve replaced them this many times. Either they told you and you didnt listen or they didnt tell you and just did the bare minimum.

Heres a good understanding of positive crank pressure.

beesandgoats.com/boostfaq/g2icturbo.html#PCV


EDIT: heres another option


Rings..


U said it smokes on decel

Usually guides will smoke on start up
Rings will smoke on decel

So with all this info given to you, I ask how the engine was broken in.

If the AFR's arent right then you could easily damage the rings.

So with that being said, read this and I hope you broke in the engine correctly

Laskey Racing Online Store




So you have a lot of good people telling you it could be these reasons.. Its up to you to troubleshoot and figure out what the problem is.
 

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Discussion Starter #16
Drill out the stock pcv and install a tube to it and point it to the ground.. its called a draft style pcv system.. and cars used this setup for years before emissions control.
Currently Setup is just black box, hose to PCV valve, hose to intake nipple on JRSC manifold. On the valve cover I'm just running a filter.

Is there any point to drilling out the PCV valve in this case? Why not just run a short hose of the block box pointed down. Wouldn't this achieve the same thing for a short test?

Itll all have to wait until the trailing arm/LCA bushings are all done and back in. Ill give it a go then and go from there.
 

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Currently Setup is just black box, hose to PCV valve, hose to intake nipple on JRSC manifold. On the valve cover I'm just running a filter.

Is there any point to drilling out the PCV valve in this case? Why not just run a short hose of the block box pointed down. Wouldn't this achieve the same thing for a short test?

Itll all have to wait until the trailing arm/LCA bushings are all done and back in. Ill give it a go then and go from there.
Of course you can, just use a tube from the black box and point it to the ground.. but how is the tube going to stay in once it gets hot.. it will more then likely fall right out. This is why I drilled out the stock pcv and took the plunger out, so the drain tube will stay in place. you can do what you want for the test, its like that on my boosted setup and i have no problems with access crank case pressure.

Read about PCV systems and learn how they work. Then you will understand why you don't want to run a stock pcv valve routed to the manifold on a boosted setup. If you must run a PCV valve you need to install one like a toyota supra has.. so it stays shut in boost and not open like a Honda pcv..The honda PCV is not designed for boost so when your motor sees boost the valve will open. If the stock honda valve opens in boost your pressurizing the block with how ever much boost your running, witch will lead to oil seal leaks... make sense?

I agree with everyone on the valve guides for sure though, i bet they are shot.
 

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Discussion Starter #20
Read about PCV systems and learn how they work. Then you will understand why you don't want to run a stock pcv valve routed to the manifold on a boosted setup. .
I've been trying to find a good basic write up on the principles. Regardless Ill give this all a go once I have it back up and running.

I'm leaning away from the guides being the issue, only because of them being addressed twice now (1st rebuild, and second because of oil burning). After the second time it did clear up most of it. The machine shop that did the work is full of Honda guys who generally know there stuff. Not ruling it out yet, but I want to try other options first before I speak to them about it again.

Thanks for the help guys.
 
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