high oil consumption, oil leaks across the piston rings Options

[HLANG]

I just recently did a complete 2L engine overhaul and installed forged JE-Pistons with Biral Cylinder Liner kit 96 mm bore. The compression is fine, the engine runs well but I experience a consumption of 1 liter oil per 1.000 Km. After I checked the combustion chamber I found too much oil deposits on the spark plugs and the pistons. The ring gap of the piston rings is in tolerance so I wonder why there still passes so much oil from the crankcase into the combustion chamber.

[Superhawk996]

Without knowing details of how you broke the engine in, the mileage on it, and/or whether you are running a functional thermostat and cooling flaps it’s hard to say what’s going on. Likewise you don’t mention if valve guides were replaced and properly reamed. Not uncommon to have oil pulling past worn out or improperly sized valve guides.

Whether or not you are running fuel injection or carbs (and their tuning) also plays a part in whether or not the cylinder walls are washed down leading to crazy ring wear or failure to seat the rings.

However that isn’t excessive oil consumption by the factory manual. Yes it’s more than a modern engine but it isn’t excessive. It’s more than I would want to see on a fresh rebuild. However, if your mileage is low and the rings haven’t seated fully, it will probably decrease with more mileage as the rings seat.

Could also be related to PCV pullover depending on your intake setup.

So basically too many variables.

I’d start with a leak down test to see how well the rings are seated.

[wonkipop]

Without knowing details of how you broke the engine in, the mileage on it, and/or whether you are running a functional thermostat and cooling flaps it’s hard to say what’s going on. Likewise you don’t mention if valve guides were replaced and properly reamed. Not uncommon to have oil pulling past worn out or improperly sized valve guides.

Whether or not you are running fuel injection or carbs (and their tuning) also plays a part in whether or not the cylinder walls are washed down leading to crazy ring wear or failure to seat the rings.

However that isn’t excessive oil consumption by the factory manual. Yes it’s more than a modern engine but it isn’t excessive. It’s more than I would want to see on a fresh rebuild. However, if your mileage is low and the rings haven’t seated fully, it will probably decrease with more mileage as the rings seat.

Could also be related to PCV pullover depending on your intake setup.

So basically too many variables.

I’d start with a leak down test to see how well the rings are seated.

@Superhawk996

ever noticed the typo/misprint in oil consumption amount in that spec posted.

says per 1,000km for the litres. and per 6,210 miles for the us gallons.

they have the litre amount correctly transposed to US gallons.
but they have left a zero off the km conversion.

should be per 10,000km? a km is 0.621 of a mile.

[Superhawk996]

1000 km =621.371 miles . . . So, decimal in wrong position . . . . 1 liter is 0.26 US gallons (approx 1 quart). . . Monday after a 3 beer lunch? (IMG:style_emoticons/default/confused24.gif)

Hopefully OP has a little more background and/or has access to a leak down gauge.

Note: 1L of oil consumption per 10,000 km isn’t plausible for an air cooled engine design with origins that date back to the 30s.

[emerygt350]

[JamesM]

What does your crankcase venting situation look like?

[wonkipop]

1000 km =621.371 mi decimal in wrong position . . . . 1 liter is 0.26 US gallons (approx 1 quart). . . Monday after a 3 beer lunch? (IMG:style_emoticons/default/confused24.gif)

Hopefully OP has a little more background and/or has access to a leak down gauge.

Note: 1L of oil consumption per 10,000 km isn’t plausible for an air cooled engine design with origins that date back to the 30s.

right.

something had to be wrong there.

but even my old type 3 squareback never used anything like 1/2 to 1 litre per 1000km.
at most it might have gone through half a litre per 3000miles going back in time between services (oil changes) which i used to do every 3000 miles max. its speedo/odo was still mph but aus had gone metric and oil was sold in metric containers. i reckon i used to do about 1/2 a litre in 4,500 km.

as to the 914, it uses precisely zero oil between changes.
and i am coming up to a change now having covered about 3000 mile since last change.
(my odo is still a US imperial mph gauge). absolutely zero oil consumption.
or its undetectable.
still the original engine never been apart. sitting now at near 48000 miles.
just on 4000 added since reawakening it 5 years ago.

i'd be a little concerned using a litre of oil every 1000 km or 620 miles if it were me.
seems like a lot - for an engine in good condition.
1/2 a litre would be not such a worry.
but i guess it depends how much high speed cruising in hot weather you do?

[Superhawk996]

i'd be a little concerned using a litre of oil every 1000 km or 620 miles if it were me.
seems like a lot - for an engine in good condition.
1/2 a litre would be not such a worry.
but i guess it depends how much high speed cruising in hot weather you do?

Yup - used to have the opportunity to hit triple digit speed on a daily commute way back when. Consumes more oil that puttering around town. (IMG:style_emoticons/default/happy11.gif)

[TMM914]

Yup looks like a leak down test will tell you…..rings or valve seals.

[930cabman]

Oil ring gaps facing down?

[JamesJ]

Perhaps these oil consumption figures were published to avoid warranty work.

[wonkipop]

i'd be a little concerned using a litre of oil every 1000 km or 620 miles if it were me.
seems like a lot - for an engine in good condition.
1/2 a litre would be not such a worry.
but i guess it depends how much high speed cruising in hot weather you do?

Yup - used to have the opportunity to hit triple digit speed on a daily commute way back when. Consumes more oil that puttering around town. (IMG:style_emoticons/default/happy11.gif)

makes sense.
drive a 914 like it was designed for conditions - namely autobahn flat out -
all the time and i suppose that will be the case.

unfortunately the nanny state of north antarctica prohibits me from that more and more.
(IMG:style_emoticons/default/sad.gif) (IMG:style_emoticons/default/beer.gif)

[porschetub]

Lots of great replies here ,I would think it would help to know what oil is currently in the engine ? , not a lot of info on this thread ,cheers.

[Superhawk996]

Perhaps these oil consumption figures were published to avoid warranty work.

That is a very typical consumption number for vintage engines from 60s and 70s. It was a well known rule of thumb when I was a kid. Check oil level at every fill up used to be a common recommendation.

Unfortunately much of our hobby is being corrupted by people’s modern expectations.

These engines are not up to modern standards.

The same thing is happening with people’s expectations for braking and steering forces. Expectations are being corrupted by power brakes and power steering in everyone’s daily drivers. I’ve literally watched people try to park a 914 or a VW Bug trying to turn the steering wheel without rolling at all, then complaining about how hard it is to turn the steering wheel. (IMG:style_emoticons/default/headbang.gif)

Manual transmissions are now anti-theft devices. (IMG:style_emoticons/default/happy11.gif)

Hand crank windows and manual adjusting mirrors are considered a hardship (IMG:style_emoticons/default/av-943.gif)

[emerygt350]

When are you checking your oil? I find I get very different readings first thing in the morning vs any time after that, even after letting it sit for an hour.

And mine has been going through less and less oil as the motor has been breaking in. I have about 8000 miles on my top end rebuild. I also race it and do lots of high rpm driving. Maybe a 1/2 liter in 2000 miles.

[HLANG]

Thank you guys for your feedback. It seems like the oil consumption is in spec but still a little high. As this have been the first 1.000 Km for the new engine, I give the whole thing a little time to settle in while monitoring carefully.
By the way: it`s a first hand 1973 Porsche 914 that I have overhauled over the last years. I couldn`t do it without having such a good forum and many enthusiasts like you.