Blue smoke puffs @ start-up... - ZR-1 Net Registry Forums

Schrade · 06-22-2014

When I start up the motor, I see blue in the exhaust. Seems like it's lasting about 10 - 12 seconds, then stops. Car has 37k.

On the road, I unloaded a few times at dusk just today, and didn't see much exhaust in the headlights behind me - maybe some Black / fuel.

I never noticed this startup oil before, except after the front was on the ramps for more than a few days. That I figured was from being '90 w/o valve stem seals (???). Pooled head oil was draining to #'s 7 + 8, and pulling through the burn?

Is it possible that OEM exhaust was absorbing some of this oil? (and it's always done it?) And only now, with headers + straight 3" tubes, it's showing more easily?

Ideas?

Paul Workman · 06-23-2014

Normal, methinks for a 90 especially - having no oil seals on the exhaust valves. And, even with seals, a certain amount of oil gets into the plenum and pools on top of the intake valves, ready to be sucked in and burned at start-up.

If as you say, it last for only the first few seconds, I wouldn't give it a second thought. Keep an eye on consumption, and realized these motors seem to use the top half of a quart, according to the dip stick, and slows after that, unless you're putting your foot in it a lot.

I've got a 90 with a valve job done less than 5000 miles ago, and new seals were installed on all the valves at that time. Still it puffs blue if it has been sitting a while (as does Ami's 91). I don't have my oil catch can installed yet. Maybe that will reduce the oil in the plenum, hopefully. But, a blue puff on initial start-up is nothing to obsess about!

06-22-2014	#1
Schrade Join Date: Dec 2012 Location: NC Posts: 1,786	Blue smoke puffs @ start-up... When I start up the motor, I see blue in the exhaust. Seems like it's lasting about 10 - 12 seconds, then stops. Car has 37k. On the road, I unloaded a few times at dusk just today, and didn't see much exhaust in the headlights behind me - maybe some Black / fuel. I never noticed this startup oil before, except after the front was on the ramps for more than a few days. That I figured was from being '90 w/o valve stem seals (???). Pooled head oil was draining to #'s 7 + 8, and pulling through the burn? Is it possible that OEM exhaust was absorbing some of this oil? (and it's always done it?) And only now, with headers + straight 3" tubes, it's showing more easily? Ideas? __________________ I'm getting my snappics / threads removed blindly as fast as I can, to get in compliance with copyright / license TOS on the boards here (lots of FSM pages and other copyright / license violations on my part; sorry guys). And thanks to all the guys who didn't whine when I posted those FSM copyrighted / licensed stuff in my threads... ( :thumbsup: [b]and to think I complied with a mod's request to delete a pic of him in a Challenge Car in NCM Museum, so he wouldn't get in hot water)[/b] Thanks to several guys here for sending parts FREE; BearlyFlying, WeGone, Geezer, GoldCylon, and more there, TonyD, mike100, fletchusmc... 1990 #2794; 4L60e Stage V by RPM Transmission, TCI Dedicated TCM, OBX Stainless, Power Effects 3" [IMG]https://lh5.googleusercontent.com/-GHpfzty7DVU/UQn-0Ru2xAI/AAAAAAAAA14/08mz1p4QLD4/s445/Screenshot-5.png[/IMG]

06-23-2014	#2
Paul Workman Join Date: Nov 2007 Location: Squires (near Ava MO in the Mark Twain N'tl Forest) - Missouri Posts: 6,493	Re: Blue smoke puffs @ start-up... Normal, methinks for a 90 especially - having no oil seals on the exhaust valves. And, even with seals, a certain amount of oil gets into the plenum and pools on top of the intake valves, ready to be sucked in and burned at start-up. If as you say, it last for only the first few seconds, I wouldn't give it a second thought. Keep an eye on consumption, and realized these motors seem to use the top half of a quart, according to the dip stick, and slows after that, unless you're putting your foot in it a lot. I've got a 90 with a valve job done less than 5000 miles ago, and new seals were installed on all the valves at that time. Still it puffs blue if it has been sitting a while (as does Ami's 91). I don't have my oil catch can installed yet. Maybe that will reduce the oil in the plenum, hopefully. But, a blue puff on initial start-up is nothing to obsess about! __________________ Good carz, good food, good friendz = the best of timez! 90 #1202 "FBI" top end ported & relieved Cam timing by "Pete the Greek" Sans secondaries Chip & dyno tuning by Haibeck Automotive SW headers, X-pipe, MF muffs Former Secretary, ZR-1 Net Registry