my friend got a dohc zc they rebuild and for some reason the engine seems to have smoke from the tailpipe. it has some at idle and when reved to about 2k etc. but sometimes disapear when idle...

idk whats the problem but what could it be.
the rings had a hard time going in be pounded in etc.,
and i heard one of the cylinders was 3,000 of inch over? so they sent the block to machine shop..


it was like that before the build when its cold and etc. but it looks the same now but smoking when its normal temp.
i think it was also white with blackish/blue idk. smells funny and had water looking near the exhaust pipe.

is it normal for the engine to smoke after a rebuild???

 

BUMP anyone????

 

is it normal for the engine to smoke after a rebuild???

 

no, did you hone the block? or replace the valve seals? and when you said pounding in the rings did you mean they werent going in so you beat them into the bore?!?

 

I have seen rebuild engines smoke several times, it was always someone fukced up.
the bored but didnt hone, or just didnt hone at all with new rings, or they cheaped out and didnt replace valve seals.

 

my friend said that they didn't hone the block bc one cylinder was 3,000 of an inch oversized.
they sent it to the machine shop to get it done.
also idk if they changed the valve seals,
and yes they still pounded it in he said it was hard to go inside???

 

Seriously, you shouldn't have to pound a piston into a cylinder. If it had a hard time going in either the piston wasn't matched to the bore properly or the rings were gapped incorrectly. In either case I'm sure the damage is done.

 

They should have honed the block, and you never have to pound pistons in, should any take light taps.

 

yea or possibly you didnt clean the head or block before putting on the new HG. either way something is messed up and it needs to be taken back apart

 

i didnt rebuild the engine my friend one. i don't know he told me that the engine had smoke before and idk it still is the same smoking white somewhat blackish what else could it be?? is the engine F***ed???
and can the engine burn white smoke if its from the oil he said he put when installed the piston rings??? its been 100 miles about run and still same will it go away??

 

might have damaged the rings by pounding pistons in. gonna have to dis-assemble it and inspect it and most likely, also machine it. also have the head machined too. ask them for a valve job and resurfacing if it needs it. also replace the valve guides regaurdless what the shop says. i never refurbish them-just replace them. and also use new head bolts. but it needs to be inspected by a machine shop. your friend should probably have the machine shop assemble the engine too. IDK but pounding in pistons isnt the way to build an engine so i'm not sure if engine building is in your friends skill level. thats my opinion though

 

rip it apart and take a look, and for god sakes dont let your friend ever build another engine without training, he clearly has no clue how to properly assemble a engien.
White smoke is water, blue is oil burning internally.

 

could it be a cracked cylinder or head but they said they sent it to the machine shop,

is reusing the head bolts Bad?

 

re using the bolts is not recommended. there are some members on here that will debate this but basically you wanna use new bolts. the bolts get fatigued and stressed from the torquing on them and also from a lifetime of heating and cooling. just replace them.

 

yea the head bolts are not reusable. people do but you shouldn't. as far as a cracked head or cylinder, its possible but not likely. from the sounds of how it was put together id bet my money that it wasnt put together right. maybe he didnt stagger the ring end gaps? maybe the hone job wasnt at a steep enough angle and the oil rings couldnt clean it all off. no matter what the engine needs to come back apart for it to be fixed.

 

he says it only happens sometimes the smoking etc.
he told me that it just might go away after the brake in but idk i told em. but for sure if it don't go away, does he have to re take apart engine then??

 

i would take it apart and inspect it before any more damage is done. better to be safe. something must be wrong because the only smoke i ever get from engine rebuilds is paint burning a little sometimes. or sometimes the car has oil inside the cat and thatneeds replacing. but thats it.but then again, we dont pound pistons in either. inspecting it would be best

 

did you even read the 10 posts above yours?