Burning oil, how much is too much?, Engine rebuilt and now with about 4,000 miles on it... Options

[MikeInMunich]

Greetings again from Munich gentlemen! (IMG:style_emoticons/default/beerchug.gif)

The engine in my car was rebuilt and expanded from its original 1.7 to 2 liter. I don't recall off hand if it's 2056 or 1911 cc.

I'm using the Porsche 20-50 oil and am currently replacing about 400ml every 5oo km. This seems to be quite a lot to me. I've added about 2 liters over the past 2,000 km, so it's burning about a liter per 1000km. That's about a quart per 600 miles.

A freshly rebuilt engine will burn more oil, but until when, as in, how many miles?

How much is roughly normal? (IMG:style_emoticons/default/confused24.gif)

Thanks for your feedback!

M.i.M.

[Dave_Darling]

That is within the "acceptable limits" in the owner's manual, but I think it's more than I would like to see.

If you've put over 2000 km on it, it should be broken in already. My guess is that the rings did not seat very well. Try a compression test and then a leak-down test to see if any compression is leaking, and if so where from.

--DD

[IronHillRestorations]

I'll 2nd DD's comment. Not ideal, but just above the generally accepted limit, and not good for a new engine.

[MikeInMunich]

Thanks Dave. I'll report back after I do those tests, but I'm unclear on how to determine "from where". What are the possibilities! (IMG:style_emoticons/default/confused24.gif) How can I determine where??

M.i.M.

[Rand]

I'm unclear on how to determine "from where". What are the possibilities! (IMG:style_emoticons/default/confused24.gif)

Meaning valves vs rings, etc.
Here's some info:

https://mobiloil.com/en/article/car-mainten...a-leakdown-test

[MikeInMunich]

I'm unclear on how to determine "from where". What are the possibilities! (IMG:style_emoticons/default/confused24.gif)

Meaning valves vs rings, etc.
Here's some info:

https://mobiloil.com/en/article/car-mainten...a-leakdown-test

Ah. Thanks.

[porschetub]

I'm unclear on how to determine "from where". What are the possibilities! (IMG:style_emoticons/default/confused24.gif)

Meaning valves vs rings, etc.
Here's some info:

https://mobiloil.com/en/article/car-mainten...a-leakdown-test

Ah. Thanks.

How was the engine run in ?,did you constantly change the load to keep gas pressure on the rings,did you avoid idling the car for long periods for instance, you have done more than enough time on the engine for the rings to bed in correctly,problem is they most likely won't get any better now.
Unfortunately the only cure is to pull the barrels off and hone them lightly to bust the oil glaze,sorry to hear you have this problem (IMG:style_emoticons/default/sad.gif)

[Tom_T]

Hey Mike,

IIRC the owners manual says up to 1 qt per 800 miles for even the factory fresh new engines, & over time - although mine never used more than maybe 1/2 qt between my 3000+/- mi oil changes - either before (45-140K from factory) nor after (140-172K stock rebuilt) the rebuild of my 2L.

IIRC yours isn't a stock motor, but the idea is the same or very similar, & I think Porsche used the 1/800 on both 4s & 6s on all models, from 356 days on up to maybe the mid or late 70's, when they had to crack down even harder due to smog controls..

So 1/600 is a bit high even by the somewhat generous factory standard. In addition to the tests mentioned above, you might also check for leaks first, cuz I'd think that you'd notice at least some blue smoke at that burn rate, if it's not leaking somewhere hidden to your eyes.

Good Luck! (IMG:style_emoticons/default/beerchug.gif)
Tom
///////

[MikeInMunich]

Good info, thanks Tom.

[MikeInMunich]

Hey guys!

I was on the autobahn yesterday to go to a D-Jetronic workshop with Dr. D-Jet, a guy who knows more about this system than almost anybody in the world and discovered upon arrival, after almost 1.5 hours of driving between 90-100 m.p.h. / ca. 4500-5000 rpm, that I indeed have a significant oil leak at the rear main seal. I was aware of this but had thought it was very limited based on how much was showing up on the pizza box I keep on the floor of my garage, but apparently as the oil thins when the engine is hot it's a lot worse than I thought it was. (IMG:style_emoticons/default/blink.gif)

So I'll be pulling the trans and clutch to change it soon and then see how it goes with oil consumption after that. The good news is that I've not been burning apparently anywhere near as much as the 1 liter per 1000 km that I've been losing.

I have the following question: first off, I just realized yesterday that I'm missing the rubber seal that goes around, more or less, the engine tin, on the passenger side. When I had arrived yesterday we opened the engine hatch and saw a significant patch of oil on the edge of the tin near the injectors, under the plenum, due to the 2-3 cm gap there which should be sealed off but isn't. Is this very surprising for you, as it is for me? How the hell did oil get sprayed up through that gap?? (IMG:style_emoticons/default/confused24.gif)

Also, any feedback regarding the main seal and how / why it may be leaking on a rebuilt engine?

Thanks!

M.i.M. (IMG:style_emoticons/default/beerchug.gif)

[r_towle]

rear main seal
rubber o-ring on flywheel

you may have forgotten to replace the ring.

aslo, there was a run of crappy rear main seals for a while.
Goetz worked for me.
Set it just even with the case, no deeper.

Rich

rich

[MikeInMunich]

http://www.914world.com/bbs2/index.php?sho...p;#entry2305994