Oil burn diagnosis (minor)

[saki302]

Hello, I hope everyone is surviving quarantine!

My car with the roush 427r puffs a little oil smoke from the passenger side when revving from idle (slight). I only noticed it while watching a drive by video on the track, it puffed a little smoke as I did a high rev hard acceleration shift from 1-2 gear.

It's not terrible, but I'm a bit OCD so I will chase this stuff until it's either too expensive or impractical to fix

I pulled each spark plug on that side- they all looked fine except plug #8, passenger side rear. After a track day and a couple hundred miles it was slightly oily.

From researching it, it looks like one of three things, one easy (valve guide oil seal(s)), one easy-ish (infamous roush intake manifold gasket failure), and one.. never mind (piston oil control ring).

Based on the symptoms of a light puff on a shift after a hard acceleration, and wispy puffs on rev up in neutral from idle (cold or hot it seems), what do you think the likely cause is?

I went into the intake with my janky Chinese bore scope, and the intake valve of #8 does look like it has more carbony/sooty crap on it versus the other cylinders. I'm leaning toward valve seal or infamous intake gasket. Keep in mind the bore scope kind of sucks, so visual field isn't great. It took some wrangling to get it in position to focus on the valve.

Thanks!

-Dave

P.S.- this and my leaky oil pan gasket I plan to swap with Moroso at the next oil change are hopefully the last things before I just enjoy driving the car. I'll have to rebalance the wheels too.
The pan gasket (I swapped a Fel Pro 1Pc) drives me nuts- it doesn't leak much if at all if you go for an immediate drive, but will leak a few drops if you idle it around and don't take it out. Like an SR71, leaks cold, seals hot :P

[blykins]

Generally a puff of white smoke when you let off the gas (higher vacuum situation) is the engine pulling oil in from above.....manifold gasket, valve seals, valve guides, etc.

[saki302]

I took the pace car video and edited it so you can see the clip

https://youtu.be/e7kopTRAaKk

I'm ordering the intake gasket and valve seals- they're cheap. Nice to have on hand anyways, and I need another oil pan gasket anyhow.

-Dave

[olddog]

Based on all the threads I have read over the years, Roush has had a lot of valve stem seal issues. No intake issue stuck in my mind, but my memory is failing. I think I would do the valve stem seals first.

Often valve seal will belch blue when you first start the engine after it sits a day or two, as the oil will run down the valve stem. Oil will run away from the intake gasket. That may help diagnose it. You can prove a valve stem leak, but I'm not so sure a lack of a puff proves anything.

If you could attach a gun cleaning cable with a clean cotton swab to the scope and run it a bit into the head, wiggle it around, and pull it out, then see if there is oil on the swab. If it is dry carbon the gasket is good, assuming you rubbed it around enough. If there is oil the gasket likely leaks. However if there is a lot of cam overlap, reversion flow might blow oil back toward the manifold, from a valve stem seal.

Its a bit hard to prove what it is by inspection, without turning bolts. It's a much surer thing to just change the seals and see it that fixes it. If not pull the intake and inspect very well to see if it was leaking.

[Gaz64]

If they are the white teflon seals, chuck them all in the trash.
I've seen a few failures from heat and poor installation techniques.
Go for viton to suit your stem and guide diameter.
Ensure adequate retainer to seal clearance at full valve lift.
Lots of measuring, especially with a sporty camshaft.

Gary

[saki302]

Thanks everyone, I ordered a set of the viton seals from summit.

They are AFR heads, but I'm not sure what the seals look like. I had them open when I did the valve cover gaskets, but the only pic I have doesn't show the seals.

It's a fairly cheap fix if it's the seals, or intake. I may just do both anyways, we have loads of time and itll make me feel better ��

-Dave