Printable Version of Topic

Posted by: 914Timo Jun 13 2003, 03:00 AM

Hopefully someone could hepl me....

Where is the promblem ??

When I start my 3.0L six, it blows big smoke cloud. Yesterday I opened the right side valve cover. There came out about 3 liter oil Before that the engine had been not running about 6 days.

Is it so, that the oil pump let the oil drain from the tank to the oilpan ?? Is there somewhere some kind of back-pressure valve, or should the toleraces in the oil pump be so tight, that no oil can go through it?? Should the oil pump be fluid-tight when the engine doesnt run ???

Or, is it normal that you find your oils in the engine after couple of days ?? How is it ?? Any experiences ?? Any advices ??

Should I chance new valve steams ?? Or pistons and cylinders...

Posted by: Jeroen Jun 13 2003, 07:37 AM

Timo,

Dunno, maybe you worry too much.
Smoke on start-up is very common and nothing to worry about
It's because of the flat 6 configuration... since the cilinders are positioned horizontally, oil seeps past the rings and gets into the combustion chamber when the car isn't running.
This (very small amount) of oil is burned on start up.

If it keeps smoking, then there is a problem ofcourse.

Worn out valvestems will only smoke up on accelleration or decelleration (I always forget which one )

cheers,

Jeroen

Posted by: 914Timo Jun 13 2003, 08:05 AM

You are right Jeroen, I worry too much....

But, my theory is that they were not so supid at Porsche when they design the engine. There have to be some explanation.

One of my theory is that the capacity of the oil tank is not too much and the oil level should never rise to the cylinders. I hope somebody could say if I am wrong or right. Otherwise I will test it....

If the theory obove is right, then the oil may flow to the exhaust port through the valve steam. I think that could be possible too.

Couple of weeks ago I cleaned (from rust) and painted my headers. Before that I removed them from the engine. Then I noticed there were oil in couple of exhaust ports. Damn, I should have look more closely that. I just thought it was there only cause the engine had not run in many weeks. I was too busy to worry about that then...

Posted by: joea9146 Jun 13 2003, 08:33 AM

Taking the valve cover off and having oil dump out is normal.
The oil does drain back into the motor.
Finding oil in the exhaust port is not ok.
Could be bad valve guides or bad valve seals. How much smoke to you get on startup ??? How much oil did you put in the motor .... are you running CIS is the oil in the Intake Air box ?

Posted by: need4speed Jun 13 2003, 11:26 AM

It's not that Porsche was stupid for designing a flat-opposed engine.
Every engineering project is always a series of trade-offs.

The flat-opposed engine design is great, because it maintains a low center of gravity, and low profile, which allows the car to be designed in such a way as to improve aerodynamics, and the low center of gravity, of course, is great for handling. But an unfortunate side effect is that sometimes oil seeps into the cylinders.

Other engine designs are, what they are. You trade one weakness for another.

On the other hand, if you feel that you've overfilled your engine with too much oil, there's a simple soution. Drain it, and refill it with fresh oil to the correct level.

Posted by: 914Timo Jun 13 2003, 01:01 PM

Valve guides are new, but I used old valves and I know they are nearly in the worn out limit. Could it cause this ??



Very hard to describe. When I start it, I can clearly see the big smoke cloud from the rear view mirror. I am sure this is not normal. I know some other Porsches here.



I have original 914-6 oil tank and I have measured the level is ok. There should not be too much oil, but .....



No, I have Webers.

The idea about bad valve seals was so good, that I have already ordered new set. Hope it will help.

Posted by: J P Stein Jun 13 2003, 01:02 PM

A problem with no solution....but a "work around".

My motor drains most all of it's oil into the sump when it sits for a week or so.....thru the pump, by the main brgs....yada. Don't think it's supposed to do that, but there it is.

Some leaks by the rings and into the combustion chambers to boot.....smoke on start-up.

The "problem" is that if the tank is effectivly empty, there is no oil for the pump to pressurize the system.....not gud. I spin the motor over for 30 sec or so....sometimes longer( as I have carbs and it don't like cold starts) to get oil into the tank.

When I start it every day, "the problem" disappears.