Leakdown Done - Questions and Inputs

[kyngfish]

In the middle of a "while you're in there" cautionary tale. What started with just a single broken torsion bars turned into:

1. New shocks and torsion bars front and rear (sway away / bilstein)
2. New turbo tie rod ends
3. New Speed and Flywheel sensors
4. Injectors out for ultrasonic cleaning
5. Valve covers off for valve adjust, gasket replacement, paint
6. Spark plugs - cap and rotor
7. A Arm bushings
9. New lower ball joints
10. Sway bar bushings
11. Rebuild pedal cluster
12. Spring plate disassembly, cleaning, and bushings
13. Eventual alignment and corner balance
13. Chasing down a vac leak
14. Disassemble, polish, paint and rebuild rear calipers

( I just wanted to write it all out... jeez)

I also finally did a leak down test. (On an uber cold engine) When my car is cold and I sit at idle too long, I will blow white smoke. So I was 100% prepared for doing a top end rebuild, but low and behold, all of my cylinders were at 2%-4% loss except for 4 which was around 6%.

So. For a car with 95k miles are those results fishy? I've had the car over 5 years and no idea if the PO did a top end rebuild. If the cylinders are in such good shape, why idle smoke?

My plugs looked slightly whitish which also suggests a lean condition, hence chasing the vac leak.

Pics below. Also my sweet leak down extension I made with a swivel connector because getting at some of those plug holes is a PITA.

[darrin]

what's your oil consumption like?

[kyngfish]

QT every 600-700

[al lkosmal]

smoke, when sitting and idling, can be caused by worn/cracked valve stem seals and probably worn guides. do you see any smoke on decel?

worn guides/seals do not show up in a leakdown test.........

[kyngfish]

No smoke on decel

[Bill Douglas]

Originally Posted by kyngfish

So. For a car with 95k miles are those results fishy? I've had the car over 5 years and no idea if the PO did a top end rebuild.

In theory it should be fine for the next five or ten years.

How about giving it death on a track for the day then check the readings again. It doesn't seem right

[Flat Six]

Kyngfish, does the smoke go away once you've driven away? If it's more bluish than white could be a slight oil overfill. But -- and this is an oddball, longshot -- I experienced something similar when I lived in Portland, but only ~October-March. Drove me batschit crazy for a while, but cool/cold overnight temps w/relatively high humidity = condensation, I assumed in my exhaust. Got a little white smoke just after startup as the water vapor steamed off. Saw water droplets dripping from my exhaust tip, gave me my first clue. Again, longshot but might be worth a look. Good luck.

[Arith2]

Originally Posted by Flat Six

Kyngfish, does the smoke go away once you've driven away? If it's more bluish than white could be a slight oil overfill. But -- and this is an oddball, longshot -- I experienced something similar when I lived in Portland, but only ~October-March. Drove me batschit crazy for a while, but cool/cold overnight temps w/relatively high humidity = condensation, I assumed in my exhaust. Got a little white smoke just after startup as the water vapor steamed off. Saw water droplets dripping from my exhaust tip, gave me my first clue. Again, longshot but might be worth a look. Good luck.

What droplets coming from your exhaust is 100% normal. That means your catalytic converter is working normally. Blueish smoke is coolant burning. Slightly overfill of oil IS NOT going to cause this.

Check crankcase pressure and do a dynamic compression test. Leakdown only tells you so much. If there are no oil leaks and you're burning that much oil, it's rings not scraping oil of walls or sealing, leaking valve seals, or possibly a scratched cylinder wall(highly unlikely unless you run on low oil alot).

Sent from my LM-Q710(FGN) using Tapatalk

[kent olsen]

Catalytic converter??? My cars are all too old for one of those.

[kyngfish]

Originally Posted by Arith2

What droplets coming from your exhaust is 100% normal. That means your catalytic converter is working normally. Blueish smoke is coolant burning. Slightly overfill of oil IS NOT going to cause this.

Check crankcase pressure and do a dynamic compression test. Leakdown only tells you so much. If there are no oil leaks and you're burning that much oil, it's rings not scraping oil of walls or sealing, leaking valve seals, or possibly a scratched cylinder wall(highly unlikely unless you run on low oil alot).

Sent from my LM-Q710(FGN) using Tapatalk

Given the state of my valve covers I think I was leaking a fair amount from them.

The white smoke is reasonably substantial. Only happens when the engine is cold or if I start it and idle for a few minutes after driving the car and letting it sit for an hour then coming back to it. Idle at temp doesn’t cause any smoke. The smoke isn’t as blue as what I would see say coming out of my lawn mower with bad rings. But it’s not white white either and doesn’t feel like condensation.

[kevstens]

How did you make the extension? Could give a few more pictures of it? Thanks

[kyngfish]

Originally Posted by kevstens

How did you make the extension? Could give a few more pictures of it? Thanks

Look up jegs compression tester extension. I cut it down with a diamond blade on my grinder and kept it as level as possible because it’s too long. I cut it down to about the length needed to get from the valve covers to the plug hole. Then rethreaded with a tap that fit an npt swivel connector and some Teflon tape. Easy peasy.

[darrin]

Originally Posted by kyngfish

QT every 600-700

IMO, that's the value to focus on -- unless you have a small river of oil under your car, your oil consumption is not being caused by external leaks (I was shocked by how far even a a tablespoon of oil spread across the ground) -- your compression test is showing piston/cylinder integrity with the valves shut (so isn't capturing whether the oil being sucked down through the worn valve guides when valves open).

Suspect you'd find a fair bit of horizontal (side-to-side) play on at least some of the valves' stems, which is indicative of worn valve guides and that (like mine), your carrera is one of those that's succumbed to worn valve guides and will need a top end rebuild in its future. And, further suspect that your cat is doing a great job of burning off the oil that's escaping past your valves.

[RedCoupe]

Originally Posted by al lkosmal

smoke, when sitting and idling, can be caused by worn/cracked valve stem seals and probably worn guides. Do you see any smoke on decel?

Worn guides/seals do not show up in a leakdown test.........

+1

[kyngfish]

Well. I’ve got the engine mostly back together now so after I find the vac leak I’ll drive it for a summer and see how it goes. Then maybe do a top end next winter.

I also was under the impression that 500 miles per qt was really the number to aim for for a top end. Is that not correct?

Again. I’m getting zero smoke on decel...

[911pcars]

Lube oil can travel in two directions past the piston rings.

During acceleration, the piston compression rings can allow excessive combustion pressure (blowby) to pass into the crankcase. The resultant pressurized crankcase passes this onto the factory crankcase/oil tank vent system (or leaks externally past faulty gasket surfaces), then back to the intake section of the engine to remix with fresh air/fuel mixture. This also occurs while the piston rings are wearing in with their cylinder surfaces. That's one source of oil consumption.

During decel, a closed throttle creates more engine vacuum. This tends to draw in additional oil via the cylinder walls or other easier access points into the combustion chamber (e.g. valve guides).

White exhaust smoke usually indicates water vapor from normal cold engine combustion - condensation through the exhaust system. Water-cooled engines also exhibit this during cold weather starts.

Oil consumption during early engine miles is usually due to the piston rings breaking in with their cylinder walls. There is no "break in" period with the valve train (guides, valves, valve seals, etc.). It's not normal for excessive oil to creep into the combustion chamber from these components.

Visible blue smoke indicates lube oil in the combustion process. This could be from an overfilled oil sump, worn piston compression and/or oil rings, loose/worn valve guides or a structural failure (crack) in an engine oil passage.

Excessive blowby increases oil consumption and it may occur without obvious blue smoke.

Hope your oil consumption is due to normal/extended break-in. With more miles, oil consumption break-in might be better or what it is.

There's no quick check other than a parts tear down inspection. You could remove the valve covers and wobble the upper valve stems to which would indicate excessive valve guide-to-valve stem clearance. Also make sure the valve stem seals are not damaged or installed incorrectly.

Sherwood

[proporsche]

kingfish..your oil consumption is way below standard.....it is usually 1-2l per 1000 km...
my engine is using only 3/4 of L per 1000 km........corrected... to make it less confusing as Spuggy said...
here is the info from specs....

[spuggy]

Originally Posted by kyngfish

The white smoke is reasonably substantial. Only happens when the engine is cold or if I start it and idle for a few minutes after driving the car and letting it sit for an hour then coming back to it. Idle at temp doesn’t cause any smoke. The smoke isn’t as blue as what I would see say coming out of my lawn mower with bad rings. But it’s not white white either and doesn’t feel like condensation.

White smoke is steam. From water vapor in the hot exhaust gas condensing into the cold exhaust system, and condensing into the cold exterior air. Yes, even on air-cooled engines.

Blue/grey smoke is oil, on start an initial puff from seepage past the guides or wet-sumping is not unusual.

Black or dark grey is gas, from rich mixture. Like a motor has when you start with cold enrichment.

Steam from a cold motor won't be white white - because the mixture will be rich, as well.

Start cold and let it run for 30 seconds to a minute - water droplets or a little stream running out of the tail pipe, like every ICE on the planet when ambients are cooler and the exhaust system is still cold? Normal.

Watch a TV show or movie with vehicles shot in cold weather. Everything does it on initial start. It's a very obvious continuity fail (like when the vehicle is supposed to be hot, but they obviously just started it up for the shot).

Still getting white smoke when the exhaust system is fully up to temp - eg the end of the tail pipe is too hot to touch? Not normal.

The factory oil consumption figure (given in litres per 1000 km, not quarts/1000 miles) is an "acceptable" figure. Motors driven harder use more oil - and motors which aren't hot use more oil, because they're still expanding to working tolerances.

1 litre/1000 km translates to 1.05 quarts/621 miles. Doesn't look like anything to be concerned about to me - especially if that's short journeys with warmups and lots of idling.

[yelcab1]

I get this question all the time. Why is there water coming out of my exhaust. It's chemistry.

HC + Oxygen = CO2 + H2O + Heat (numbers need to match up of course)