Johnny G Pipe

Hi folks. Still having a happy time with my C4 as a daily driver, full convert to the sound with no cat now..

Anyway, the good old oil leaks seemed to disappear for a while (no droplets on rear deck, no smoke drifting up through the spoiler in traffic) - and I had started to wonder whether it was related to the oil level, which has lately found its way down into the red on the gauge.

So, I just topped her up to just under max and no more, as usual, and straight away I have the signs of the leak back, I left the car in the work car park this morning with a column of smoke gently rising from the tail!

Just wondering if this was significant. I'm sure the engine is leaking a little from the usual o-rings and cylinder base, but maybe this suggests a big leak from breather hose or oil pressure sender or something that doesnt cope with much oil when the level is lower - does this make sense, or is the crank oil level kept completely constant with circulation to and from the tank? Would be great to stave off getting the engine out for as long as possible if I could fix some of these things myself of course.

Interested in any thoughts before I start to pull bits off the top of the engine to investigate..

ghouth

Hi Johnny,
Which C4 is yours? I can understand that yours is an air cooled one. I have a 964 C4, and according to the manual, the destance between max and min in oil level gauge, represents 1.5 liter. For me, I usually depend on the dip stick when the whole system become really hot.

Shoaib

vincer77

On 993s filling beyond about half way point leads to higher oil consumption presumably due to leakage. Not sure of pathway.

FeralComprehension

I see more leakage when I go over half way up the dipstick, FWIW.

DarrylH

Perfect sense. I'd suggest getting the car hot - oil-cooler-fan-coming-on-hot, you want to be certain the oil volume is as high as it's going to be - and filling only until the oil level gauge needle is horizontal or the dipstick is at the halfway-between-marks point, whichever is your favoured method of measurement. More oil than that is unnecessary and the excess get dumped into your intake, possibly leaking out along the way.

dfinnegan

Good point to make sure the oil is really hot before determining the correct level.

This calculation shows that the volume will grow a half quart.

I generally run my oil gauge between the lower red mark and approximately 1/3. Often times it won't really move until it gets well warmed up.

Johnny G Pipe

Dipstick? Ahh, yes I remember that, gave up trying to use it sometime around 2003 (although that was back in the Mobil 1 days..)

Thanks for the thoughts...I have always filled it up this way and have never had problems with oil fouling the intake. Will oil only get to the crank breather (as opposed to fumes) in the scenario of a major over-fill? The car is almost never hot enough for the cooler fan to kick in, with the use that it sees (East coast Scotland, no traffic jams..).

I guess I thought that the amount of oil entering the engine was dictated only by how much it needs (not sure how it does it though - just increased oil pump work rate?), not by oil tank level - in other words surely the crankcase level should be independent of how much you put in the tank, within reason. Maybe there is a gravity effect?

sml

red is perfect.

my level sits in the red for 98% of the time during hot city driving.

leave the already hot engine idling for a further 15 mins and it will go up halfway on the gauge.

aiming to keep the level is red is perfect.

dfinnegan

+1