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 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.

[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.