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Exhaust smoke

778 Views 6 Replies 2 Participants Last post by  Frohst
So... How long should it take to burn off any oil that gets into the exhaust?

1994 RS. Abused/basket case. 290k miles. Last compression check at 280k was 160 140 140 170 or something like that.

Been having an issue with a rich smell wafting into cabin after WOT at 5-7k rpm. Figured exhaust leak pre cat, O2 sensor and ecu coolant temp sensor...

Well. Driving up a steep driveway and she all of sudden started pouring smoke out of the exhaust. Like thicccck clouds of it.

Exhaust manifold is stained/wet where it meets the gasket on cyl 2 n 3. Oil isn't chocolate milk shake (yet). Oil is ~ 1qt lower than when I filled it 300 miles ago.

I'm assuming it's headgasket and cylinder rings at the same time - but could be pcv... I had deleted the breather box on the back.
Plugged the bottom hole, routed back of block threaded breather ports to a closed catch can on firewall, same height as heater hose to cabin. Catch can vents to pcv valve and into stock I take port.
Catch can was filled to the brim so figured she could have drank oil during the steep uphill.

Curious how long a flooded cylinder should take to burn off all the oil (and praying it's not a headgasket n cylinder rings ..)
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Finally got time to tear into her (yes. It did take that long for my project log to clear up)

Pistons 1-3 look like this.
Motor vehicle Automotive tire Automotive lighting Gas Auto part

And here's piston 4.
Automotive tire Motor vehicle Automotive lighting Rim Goggles

Am I right in saying: clean edges on 1-3 the piston rings are letting go.

All that crap on piston 4: bad valve stem seal or was running rich - but only on him (injector, maybe the ring blow by on others kept them clean vs him)

And as far as rebuild at 290K... I was only planning on gaskets... But looks like I should add rings... At which point.. do the bearings? Or not spun don't touch factory work?
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You sure that's cyl #1? That looks like #4 to me. Had you performed your compression test recently? It looks like you performed one, but that was 10K mileage ago.
You sure that's cyl #1? That looks like #4 to me. Had you performed your compression test recently? It looks like you performed one, but that was 10K mileage ago.
I definitely brain farted that one. I had the numbers backwards. Editing original post, thanks!

Unfortunately no. My boroscope made the carbon on cyl 4 looks shiny and pitted metal like so I pulled the head before cycling the engine out of fear of head damage. Dumb move on my part since it would have already screwed the head up in the mile it's been driven while smoking had the valve actually dropped.

I'm committed to the rebuild just to learn, but trying to make sure I'm following best practice as I go.
Nothing obvious in ring land but hooooo boooy main and con rod bearings were rough (scratches, pitted to copper, and/or worn to copper color).

As far as crank - looks fine, nothing I can feel with a finger nail. This is the worst of it - more experienced eyes see any concern with it?
Wood Gas Machine Metal Auto part

And then cylinders to me I'd guess need a hone? (I would definitely say cross hatching is gonzo) But no clue what they are 'supposed' to look like.
Tire Automotive tire Musical instrument Idiophone Alloy wheel

(Cylinders were wiped down with acetone, photos, then re oiled - can't feel anything in the walls so assume it just needs more cleaning as far as the staining)
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Block cleaned, hone in hand, and...
Womp womp. 1 intake and 1 exhaust valve on the actual cylinder 1 are bent.

Least I know before I order parts.
To anyone pulling valve stem seals - universal valve stem seal pliers don't work. 5-15 seconds propane torch+ whatever pliers you got in the tool box does.

Wouldn't do this if you don't have head off - makes a bit of a mess for cleanup.

I'll update if I run into any issues with valve guides - doubtful with how little heat is going into the head.
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