oil consumption- rebuild or not?

[dede911]

Hi,

I already posted a question around this topic last year, but after some more miles, fixing a small leak and some experiments with different oil visco's, I'm still puzzled.
This is the story:

3.2 engine with K-jetronic
completely rebuild 12K km ago by a local experienced porsche rebuilder
Very good power and torque
Leakdown test around 8%
No smoke
running 10w60 synt oil.

Last test regarding oil consumption is around 0.8l/1000km, with a combination of streetdriving and 1h40 on track.

I think that the rings are not seating properly...

Is this the time for a re-ring, or what would you do?

Thx

André

[RSTarga]

8/10 of a liter in 1000KM? That sounds ok to me. Although for a rebuild with just 12K on it 8% seems high. Is that on all cylinders?

[Reiver]

Something is not sealing properly for a fresh rebuild. Alusils or Nicasil?

[dede911]

I suppose nicasil: i counted 11 cooling fins on the cilinders

The leakdown nbrs were all very close. This result is from 4k km ago. I can perform a new test..

André

[Flat6pac]

Consumption is not out of line with factory standards.
Bruce

[rfuerst911sc]

Try switching to conventional oil to see if that will help seat the rings ?

[tharbert]

I saw your other thread about this. It's obviously got you worried. That level of consumption is considered by the factory as the high side of normal. Other than the fact that a newly rebuilt engine probably should have a bit better leak down numbers and less oil consumption, if there are no other reason to tear it down like plugs fouling and low compression, drive it and don't worry about it (as much.)

Just a few questions that may help get a dialog started: Did you get new rings, pistons and cylinders with the rebuild? Describe. Was the 8% leak down across all P/C's? With that much leakage, did you try to determine where the air was leaking? Did you follow the break-in instructions? Something like this? Who did the heads? What was replaced?

At this point, I would certainly go back to the builder and see what she thinks. You're right. They might take an interest and decide to help.

[Reiver]

Nicasil is an easier rebuild sealing wise than Alusils. Hopefully you used a dino oil for break in and not a synthetic.
Go back to a straight dino oil and see if that helps mate surfaces.

[dede911]

Hi,

some more information:

The rings have been replaced, cilinders and pistons are reused.
Heads are rebuild by the same shop who has done this engine. This guy is already years Porsche specialist, and worked together with very well know drivers in this little country, rally as well as track....

He rebuild and installed the engine, because he wanted to do the start-up himself.
When I collected the car, there were some extra miles on the country (initial running-inn?).
I guess that the oil (when I collected the cat) was synth 5w50. That was what he recommended.
The instructions I got was to be careful and keep the revs limited to 3K for the first 500 km. Then for every 100km increase the revs with 1000 rpm.

What I can do is to execute a complete leak-down test and determine the location of the losses.
I also thought to go to dino oil, but does that makes sense after more than 10k km?

Last year already, I contacted the shop to tell him that I worried about the oil consumption, he told that me that my consumption is normal, and will still improve...

I think that the 1 or 1.5l/1000km in the Porsche manual is mainly to avoid claims. From a technical point of view, this seems very high to me.
In the past I have build several BMC (finest British engineering..) racing engines, and never had high oil consumptions with fresh engines.

André

[kodioneill]

Change out the synthetic refill with cenpeco.

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CCsQFjAA&url=http%3A%2F%2Fwww.cen-pe-co.com%2F&ei=AXluU-LhFZPQsQTwq4HYDg&usg=AFQjCNH_CE5bvnxBkTigW1BOw2V41cP5lw&sig2=vZC110t8j2XIkxz0I-YJSQ&bvm=bv.66111022,d.cWc

[dicklague]

Originally Posted by kodioneill

Change out the synthetic refill with cenpeco.

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CCsQFjAA&url=http%3A%2F%2Fwww.cen-pe-co.com%2F&ei=AXluU-LhFZPQsQTwq4HYDg&usg=AFQjCNH_CE5bvnxBkTigW1BOw2V41cP5lw&sig2=vZC110t8j2XIkxz0I-YJSQ&bvm=bv.66111022,d.cWc

CENPECO??? What the hell is that? Oil from Walcott Iowa? Do you think the OP can get that in his country?

Why not just good dino oil?

[dicklague]

Rings will seat a lot better with normal non-synthetic oil. Very surprised that your expert put synthetic in a newly rebuilt engine for break in.

[Reiver]

No one I know ever puts a synthetic in for start up/break in.
Maybe now a days it is ok but in the past it was always considered a no no.

[wayner]

Drive it harder?

[kodioneill]

Originally Posted by dicklague

CENPECO??? What the hell is that? Oil from Walcott Iowa? Do you think the OP can get that in his country?

Why not just good dino oil?

Cenpeco is a paraffin based oil great for these oil cooled engines. I didn't notice he was from Belgium. Just trying to help the guy.