I put a new engine in my car about 700 miles ago. It is a D16A6 with 75.5mm Vitara pistons and eagle rods, stock sleeves. Fairly basic setup.

The motor is not boosted yet, just running all motor until I get a trans built.

The motor runs great, has plenty or power, perfect A/F ratio, and good vacuum. The only thing I've found wrong with it is this weird smoking problem. It only does it under one condition:

I cruise along in like fourth or fifth gear and then down shift into second and let the car slow itself down. The vacuum goes up to like 24/25 in. hg., and then if I nail it after a couple of seconds, it'll burn oil for a second and then stop.

I am running .0035" PTW clearance and my ring gaps are .019 top and .020 bottom. The only thing I could think is that the much higher vacuum of letting the car rev down is pulling oil past the rings due to the large clearances and then when I get on it it burns off.

Any thoughts?

Random pic of the car to lure you into the thread:

 

I have honestly never seen a D/B Honda engine not burn oil, lol.

 

My old engine didn't burn any oil. This smoke concerns me. It's not enough to register any loss on the dipstick, even after a week of driving, but still...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SovXietday &raquo;</TD></TR><TR><TD CLASS="quote">I have honestly never seen a D/B/K/H/F Honda engine not burn oil, lol.</TD></TR></TABLE>

Fixed

 

how is your pcv system hooked up? if you have no pcv valve and your breather is open to atmosphere, you may have blow-by and not know it.

 

did you change the valveseals, when you buildt the block? if they are bad the engine tend to suck oil through them when your engine braking, (biggest pressure diffrence). since monst engines don-t have any combustion going on when you engine braking it will acumulate untill you go back on the throtle and then you burn it for a short period.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jewjew bean &raquo;</TD></TR><TR><TD CLASS="quote">how is your pcv system hooked up? if you have no pcv valve and your breather is open to atmosphere, you may have blow-by and not know it.</TD></TR></TABLE>

I have a hose going from the valve cover breather to the catch can and a hose going from the "black box" to the catch can. No PCV.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mh &raquo;</TD></TR><TR><TD CLASS="quote">did you change the valveseals, when you buildt the block? if they are bad the engine tend to suck oil through them when your engine braking, (biggest pressure diffrence). since monst engines don-t have any combustion going on when you engine braking it will acumulate untill you go back on the throtle and then you burn it for a short period.

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I used the head off of my last motor, it did not smoke when it was on the other block.

 

Under vac then back on throttle smoke is either valve seals or turbo seals.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tippyman &raquo;</TD></TR><TR><TD CLASS="quote">

I have a hose going from the valve cover breather to the catch can and a hose going from the "black box" to the catch can. No PCV.

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Do you have any vapors from the breather line? If you do, that means that you have excess crankcase pressure which would suggest a bad build.

 

Exhaust side oil seals. Oil leaks when you downshift then when you boost it all burns up and smokes out.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jewjew bean &raquo;</TD></TR><TR><TD CLASS="quote">

Do you have any vapors from the breather line? If you do, that means that you have excess crankcase pressure which would suggest a bad build. </TD></TR></TABLE>

I have some vapors coming out of the catch can, but from what I was told that is completely normal.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 93CX &raquo;</TD></TR><TR><TD CLASS="quote">Exhaust side oil seals. Oil leaks when you downshift then when you boost it all burns up and smokes out.</TD></TR></TABLE><TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tippyman &raquo;</TD></TR><TR><TD CLASS="quote">

The motor is not boosted yet, just running all motor until I get a trans built. </TD></TR></TABLE>

 

most likely exhaust vavle seals

check the plugs if they're nasty like burning oil it could beintake valve seals too.

my d16z6 stock longblock burns oil on high rpm decel like yours. my plugs are clean as hell but the exhaust has a burnt oil sludge on it cus the exhaust vavle seals are shot...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tippyman &raquo;</TD></TR><TR><TD CLASS="quote">

I have some vapors coming out of the catch can, but from what I was told that is completely normal.

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I think you have excess blow-by. I suggest you do a leakdown test

 

if your not burning a noticable amount of oil, FORGET ABOUT IT, and just run it hard.

its not worth fixing if its ring gaps unless your using a quart rapidly..

sounds exactly like my valve seal problems on an old engine (barely used any oil, and only smoked going from high vaccum to WOT, or pulling to a stoplight andgoing to full vac.. )

ROCK THAT THING

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by redzcstandardhatch &raquo;</TD></TR><TR><TD CLASS="quote">if your not burning a noticable amount of oil, FORGET ABOUT IT, and just run it hard.

its not worth fixing if its ring gaps unless your using a quart rapidly..

sounds exactly like my valve seal problems on an old engine (barely used any oil, and only smoked going from high vaccum to WOT, or pulling to a stoplight andgoing to full vac.. )

ROCK THAT THING</TD></TR></TABLE>

It is ONLY in that one condition. And after like two weeks of driving, and doing it alot on purpose to see if it still did it, it's not noticable on the dip stick.

 

i see NO PROBLEM then..haha

 

you sure it's blue smoke (oil) and not black smoke (fuel)?

maybe your ecu tune dumps a bunch of fuel from decel&gt; WOT?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by non-VTEC &raquo;</TD></TR><TR><TD CLASS="quote">you sure it's blue smoke (oil) and not black smoke (fuel)?

maybe your ecu tune dumps a bunch of fuel from decel&gt; WOT?</TD></TR></TABLE>

Definately blue smoke, that's why it concerned me.

Stock ECU.

 

i am having the same problem with my ls/vtec, so last night my buddy and i put in all new OEM valve stem seals, and did a leak down test.
i have 4% leak down, and my seals were changed, and i still get smoke on downshifts too.
i am completely lost, my engine will use a quart of oil in lik e750-1000 miles..

 

Could just be the rings seating, change the oil and look for a slight graphite look in the oil, if you have new rings and a honed cylinders it’s kinda normal. Load the engine hard to seat the rings as fast as possible don’t use synthetic oil for break-in. and it could just be the valve seals, as many have alluded too. Or I should say more than likely, it’s just the valve seals, the rings are just another possibility. good luck

 

well i already have over 6k miles on the build. just seems odd, the motor was a fresh bore to .040, new hasting rings, new gsr op pump, new acl bearings, arp rod studs, arp head studs, crower valve springs and retainers, pro tech headder, AEBS intake.
so its a fresh build, and i i seated the rings cause my leak down is low at 4-5%, so i just dont know, im not running a PCV, i have the nipple on the valve cover open, and i have a catch can ran from the back of the block.
mine happens evertime i get off the freeway, or slow down from speeds over 30, where i donwsift more.
its really embarassing.
and on break in i used 2 oil changes of castrol GTX, 10w-30, with bosch filters...