pretty sure i know the answer to this but after fitting a pretty much straight through exhaust im getting intermittent blue smoke out of my passenger exhaust im guessing its turbo seal time but it being intermittent seems odd. Always at idle but will be fine for a day then just do it while sitting

 

thanks in advance :)

Classic symptom of turbo rear seal failure is grey, not blue, smoke at idle. Particularly prolonged idle on a hot engine, when the oils thin. I assuming your assumption is this. Thing is there isn't a rear seal, not as such, it's closer to a piston ring or splash guard. It's job is to stop exhaust gases going into the turbo not to stop oil pouring out. The drain in the turbo should be sufficient to allow it out at a rate that've doesn't get high enough for this. Often the turbo gets blamed and no ones checked what there crank case pressure is, wether the turbo drains are clear etc etc. Even your PCV not working properly could cause it.

i have though about the pcv valve but thought it to be too coincidental that a week after messing with the exhaust it starts doing it. only dose it on a hot engine. iv rebuilt 300zx turbo's before but never fitted them, and sadly don't have them any more. flogged them cheep as they still needed balancing.

It's to do with pressure balance. Your old exhaust may have been applying enough back pressure for the proper route, is through the drains, to work effectively. Now you've relieved that pressure the easiest place to go is the exhaust. Try driving around the air con on, that increase in revs and load can be just enough to stop the leak.

 

Is what I described what your getting?

 

Out of interest have you preformed a compression test? If compression is poor the crank case gases may be too high and cause the same issue.

never done a compression test but will have to look into it