Smoke when stepping hard on gas after coasting

[Dustained]

The smoke is blueish, the engine is a very recently rebuilt Nissan GA16DE. Oil level is exactly where it was 1000 miles ago, when I did the oil change.

After coasting for say 10 miles or so, I step on the gas to the bottom, blueish smoke comes out for like 2 seconds, and after that I can rev it as high as I want, no more smoke. Could anyone enlighten me? Is it normal?

 

[CharBaby]

Probably some carbon buildup on the piston tops!
Or, while you're coasting, some oil is getting past the rings and then, when you go into WOT, it blows out of the exhaust!

IDK if I'd call it normal but, it can happen!

 

[berniedd]

What exactly was done/replaced during the engine rebuild? Maybe something was overlooked/not touched that should have been?

 

[Dustained]

Basically the only thing that is not new is the crankshaft and the camshafts, it is DOHC. The engine block is also the original iron cast one.

The thing is that it doesn't burn any oil.

 

[spasm3]

that sounds like valve stem seals.

 

[Dustained]

Originally Posted By: spasm3
that sounds like valve stem seals.


I have thought about that, but the fact that the oil level has stayed the same for 1000 miles makes me doubt.

It's Valvoline Synpower 10w-30.

 

[DirtyMoe21]

I would give the engine a little bit longer to wear in before I got too worried.

 

[Dustained]

Originally Posted By: DirtyMoe21
I would give the engine a little bit longer to wear in before I got too worried.


It's got about 5000 miles now, do you think it hasn't worn in yet?

 

[Quest]

blue smoke when accelerating hard after coasting indicates high vacuum (on non-turbo gasoline engines), which typically sucks the oil through valve guides and valve-stem seals.

Bottomline: have you check the valve guides for wear and clearances and also replace the valve stem seals?

Q.

 

[Dustained]

Originally Posted By: Quest
blue smoke when accelerating hard after coasting indicates high vacuum (on non-turbo gasoline engines), which typically sucks the oil through valve guides and valve-stem seals.

Bottomline: have you check the valve guides for wear and clearances and also replace the valve stem seals?

Q.


I think the mechanic did, but you know, some of those guys are not to be trusted.

 

[datech]

sometimes the valve stem seals can be installed just under the valve cover. They should have done this on a rebuild.

 

[Dustained]

Why do you guys think the oil level remains the same?

 

[Smokescreen]

Did the rebuild come with any type of warranty?

 

[L_Sludger]

bum rebuild. internal engine problem. valve seals most likely. sorry dude

tienes que reclamar su dinero!

 

[Quest]

Originally Posted By: Dustained


I think the mechanic did, but you know, some of those guys are not to be trusted.


I've seen all kinds of mechs cheated/lied through their teeth, and for that I typically oversee most of the repair process and also requested to get the replaced parts back.

You never know when a mech lie ....esp. OPE engine repairmen.

Q.

 

[Hokiefyd]

Originally Posted By: Dustained
Why do you guys think the oil level remains the same?


It doesn't take a lot of oil to cause a puff of blue smoke. I had an Oldsmobile 307 V-8 once in a beater Buick Regal that would do this. It'd puff blue smoke after idling for more than about 10 seconds (and on every cold start). The oil level never really moved on the dipstick.

 

[DirtyMoe21]

Originally Posted By: Dustained
Originally Posted By: DirtyMoe21
I would give the engine a little bit longer to wear in before I got too worried.


It's got about 5000 miles now, do you think it hasn't worn in yet?


I misread your post and thought it only had 1k on it. It should be broke in for the most part.

 

[ARCOgraphite]

Coasting for TEN MILES! I think ANY of our cars or trucks would puff some smoke.
Coming down off a big mountain pass? IN OD or 4th or 3rd or N?


Pull the plugs and look for deposits on the inner shells after some NORMAL driving without excessive coasting. If level is OK and plugs look good, I would not freak.

 

[eljefino]

+2 normal enough.

If you have decel fuel cutoff, oil will sort of linger on your piston, not being ignited, when coasting down hill. Small amounts add up over time, then when you hit the gas, whammo.

 

[Cardenio327]

OP, you are in Mexico, right?

Originally Posted By: Dustained
Nissan GA16DE


Call around to Nissan dealerships, that engine is available brand new as a crate engine for $19000 pesos. There is no reason whatsoever to rebuild a GA16DE unless you want to do it for fun.

I've worked in the auto repair industry in Mexico for 5 years. I would never have an engine rebuilt here for the following reasons; lack of parts availability, lack of cleanliness in shop practices, lack of precision measuring and milling equipment, lack of knowledge, and dishonesty caused by the pressure of competing with dishonest competitores.

Recent case with one of my customers: Late nineties Suburban 5.7 Vortec, came to me for a second opinion, misfire and clatter on cylinder #1. After advising him it isn't my area of expertise, I did some basic diagnostics for free. I opined a stuck valve, about $15000 for a complete valve job. On teardown, the crooked mechanic found a broken connecting rod, and went ahead and rebuilt the engine anyway because it hadn't damaged the block much! The customer brought it to me afterwards for my opinion, it would barely run. The crooked mechanic wasn't even able to get the cam timing right when he put it back together!