Rebuilt engine, blue smoke when started stop smoking after warms up

[Savstyle]

So,

I'm looking at a 90 z32TT. Engine was rebuilt and has less than 50 miles on the rebuild. I went to look at it and the car smokes at cold start. What the owner told me the piston rings haven't sealed and that's why it smoking.

Now i know very little about cars but, from a little research ive found 2 conflicting opinions. One is that is should never smoke and the rebuild was done wrong. The other is rings haven't sealed and it will be around 500 miles or whenever the rings seal till it stops smoking.

I'm really just trying to figure out if i should be running for the hills or if its just a little risky or if i'm good to go.

And if you need more info ask away, ill answer all that i can!

Thanks in advance

[NolimitZ32]

First and foremost, welcome to NICO, glad to have you join our ranks. As for your issue: I have never seen a car NOT smoke from all sorts of weird places after a rebuild. Unless the work was done in a clean room and the engine went through break in on a stand you will always have a bit of smoke, now if your car is billowing smoke like a diesel then yes you may have a problem. As for buying a freshly rebuilt car, i would steer clear unless you get some kind of transferable warranty. If this is something that the guy did in his garage and is dumping it 50 miles after the rebuild that would be suspect to me but I have trust issues.

[Savstyle]

Thanks,

That seems to be the consensus across all the Z forums im on.

Looks i will be avoiding it, unless he lets it go for cheap.

[earthdog61]

Some blue smoke is very common with rebuilds, I've done several dozen of them.
Just keep running the engine on regular non-synthetic oil for 500 to 1000 miles and check your spark plugs every couple of weeks least they foul.
If the motor runs and has good power and you don't hear any knocking or rattles, you most likely have a good rebuild.
Also, continue checking the radiator for scum and oil, they are signs of a poor head gasket seal.
Otherwise, don't hammer it until the engine is broken in,