smoke & fuel in sump

[svandamme]

finally got the 944 running again (after headgasket replacment and new seals front and balance shaft afts )
but it smokes immensly ... blue smoke

definately did not overfill the oil , but when i checked again... the level on the dipstick had gone up...

i don't think the fuel could go to the sump so fast from a couple of attempts to crank it.

checked compression, all nice, not much difference

drove it around, engine isn't smooth enough yet

did turn down the air meter.. to the point the engine killed...

was thinking stuck oil pressure relief valve.... got it out , looked worn , so i'll replace it with the newer type ( no spring)

what am i missing here ? anybody has some more ideas on how the fuel could get to the sump , what could cause that?

[Razorback1980]

Are you sure it's fuel and not water?

[Zero10]

As for the smoking, give it a little bit of time running and see if it clears up. If the head was off, some oil could have gotten into the cylinders, and it will take a few minutes to fully burn off.
You would hardly get any fuel in the sump from trying to crank it a few times. Certainly not enough to measure the increase, and it would evaporate the first time the oil got up to temperature.

As for not running smoothly, the blue smoke is probably related.

[nynor]

when i first got my '83 back together, bent valves, it smoked. i am sure it was from oil in the cylinders, etc. it cleared up pretty quick.

[svandamme]

Razorback
yes , very sure, it's fuel
the oil came out thin, smelling very much like fuel

zero10, i had it on idle for more then 10 minutes, it stank up the whole garage, then took it for a drive to the fuel station... and it still smoked when i came back....went back to troubleshooting after that


i had it running for 20 minutes at least... no sign of improvement
not even after i changed the oil

[Slam]

Interesting problem.

Okay, fuel comes from injectors and goes to cylinders. If it's getting into crankcase it must be getting past the piston rings, given location of fuel rail. If the car's burning oil, then oil, too, would be entering the combustion chambers via worn/broken piston rings, no? Given the symptoms, it seems like fuel and oil are moving across/through the rings. Very rich mixture? I know the CIS cars can fill up a crankcase with fuel.

Then the smoke would be blackish grey - rich mixture and oil burning.

Just guesses, of course.

Valve stem seals? Who did the head rebuild/valve job?

[alex.rhodes]

try the fuel pressure regulator/fuel damper

[Razorback1980]

My 87 had a leak in the fuel pressure regulator and damper and it was going into the vacuum lines and into the intake manifold. You can check this by pulling the vacuum line that runs to the regulator from the intake while the engine is running and see if fuel runs out. I would guess this is not the problem but something to check. Obviously fuel is running at a very high rate into the cylinders somehow and I'm just not sure how it could do that and if it was coming in through the cylinders it would be black smoke not blue. Burning oil can come from many places including valve guides and up through the piston rings or from the intake manifold somewhere. The first thing I would do is pull the spark plugs and see if one is dirtier than the others. Maybe one is coated in oil and this will tell us which cylinder is doing the burning. Look for a plug that is black in color...if it's smoking at least one will be black. If all plugs are black then we know it's not related to one cylinder alone and can rule out the rings or a certain valve guide seal. We then need to look into the injectors not functioning properly or toward the intake manifold somewhere. If only one plug is black, then we may need to look back at the head gasket or a broken head or something like that. It's hard to tell if the car isn't running smooth because of improper air/fuel mixture or if it's rough because there is a vacuum leak or something. One thing I just thought of...isn't there a seal somewhere on the intake that separates oil and air intake? Of course that wouldn't explain gas in the crankcase (sump). If that seal were leaking it could explain the burning oil. The first thing though is to find out if it's related to only one cylinder or to all of them. Pull those plugs and let me know what you find.

Thanks

[alex.rhodes]

it's been awhile, so forgive me if I screw this up....

when the car runs rich, the excess gas will eat away at the oil on the walls of the cylinders. this in turn allows blowby past the rings since they can't seat properly. therefore, gas gets into oil and oil into cylinders. Blowby pressurizes the oil sump which you can feel by taking the oil fill cap off when engine is running. When the oil sump is pressurized, it will send oil up thru the oil seperator at back of engine and into the (ICV maybe?) and into the intake. This allows the engine to burn oil and make the oil smell like gas. Also, I believe the when the fuel reg/damper goes it allows fuel seepage into vacuum system after shutdown.

[Slam]

Ah yes. Forgot about regulator and damper. But the fuel's still gotta get past the injectors. Maybe they're the problem?

[Razorback1980]

Slam, actually when the fuel regulator or damper breaks the rubber diaphram inside; the fuel runs through the pressure regulator directly to the intake manifold via vacuum lines and directly into the cylinders bypassing the injectors all together not just at shutdown but all the time. This will also feed fuel into the crankcase ventilation system filling it with fuel. Alex is heading down the road I was going to go down after he tells me if it's one cylinder or many. If it's many, then I think Alex has probably nailed the problem but again I'm guessing. If it's one cylinder burning the oil, then I would agree with your analysis and say let's look at the oil seals on the valves but that doesn't explain the gas in the oil problem...so what Alex suggested is how I'm leaning at the moment. Typically, I look at what has changed that started the problem...in this case a head gasket which isn't the fuel regulator but I can't think of any other way that massive amounts of fuel can get into the crankcase. The fuel system is fairly closed with the exception of the fuel injectors and the fuel pressure regulator. But either one of these theories would suggest black smoke instead of blue smoke. The smoke color is killing my theories. Definitely has me puzzled at the moment. Hopefully, we'll learn more about whether it's one cylinder or many and that will point us down the appropriate road.

[Slam]

Okay. So if he simply pulls the vacuum lines off the reg and damper and runs the car he should know about this right away - as had been mentioned. Since there's only one vac line for these at the throttle body, maybe pull that one and check there.

So, fuel through the vac lines into the throttle body, draining from there into the oil separator via the big vac hoses (not the lines).

BTW - Razorback - I lived in Houston for a little while during my life as a rock singer. I'll never forget the smell of the flowers as I walked out of the airport!

[svandamme]

more info:
head was done by... me... new valve stem seals, the guides were good
checked fuel pressure on the rail.... was good , both in idle and running...
i did pull all the plugs, they were all equally dirty..black oily.... they were replaced when i started working on this car...

[Razorback1980]

Okay, so that tells us that it isn't one cylinder specifically. Did you pull the vacuum line from the fuel regulator and damper? We need to know that there is no fuel coming from there. Another thing that would be informative is to run with the oil cap off and see what type of pressure is in your sump.

Unless I am totally missing something, there is only two places to get fuel out of the fuel circulation system....the injectors and the regulator/damper.

[svandamme]

i'll try that first chance i get ( car's not parked nearby )

so i pull the damper lines, both , what should or shouldn't i see?

- no fuel
- any change in running condition ?? should it go richer, or leaner?

[Razorback1980]

The fuel pump pushes fuel from the tank through the lines to the regulator then the fuel rail on to the damper and then back to the tank. This is a closed system other than to the injectors. The fuel pressure regulator and damper have rubber diaphrams inside and when they break, fuel can run back through the diaphram and into the vacuum hose that attaches to each of the devices. Because there is vacuum there and that vacuum comes from the ACM, it will suck gas from the fuel system straight back into the intake manifold anytime there is pressure in the fuel lines. This will in turn run gas into the ACM and down the J boot and into the sump ventilation system. That's my theory at this second. The thing I'm looking for is where is the fuel coming from and the only place it can leave the circulation system is the injectors and the regulator/damper....at least that's the only place I can think of. If it's coming in massive quantities through the injectors, the car probably wouldn't run, so I'm thinking it's through the regulator/damper. Hope some of that makes sense. I'm hoping if we can find where/how the fuel is entering the sump, we can fix the problem and there shouldn't be too many places it can leave the fuel circulation system.

[svandamme]

makes sense to me ! better then what i came up with so far

my troubleshooting skills, when it get past the basics are usually loud cursing,followed by threats to the car... "so you wanna be a parts donor , eh?"
while i point some other gutted chassis that's standing in that place where i rent a spot for my cars...

btw, i'm aaaawesome at taking them apart... that fact alone adds to the threats i make... cars should simply start running out of fear...

[Razorback1980]

LOL....If you can get them to run...doesn't matter how you go about it.

One thing is for sure, there are a lot of pretty smart people on here that know these cars really well. I'm not one of em but I am learning. Until I got the 87, I took mine into the Porsche dealer to fix everything. The 87 has too long a "to do" list to take it in, so I'm on here stealing information from all the experts.

[Razorback1980]

Slam,

Hope you make it back this way sometime. If you do, be sure and let me know you're coming. I don't know though...I'm pretty jealous of those who can sing well. If I even try to sing with the radio, it gives me static. I do play guitar though. Have a black and white strat and a yamaha acoustic. Don't play well, but I do play.

[svandamme]

verdict : it's blow-by
the compression test must ave been "reasonable" due to the amount of oil , the breather hose wasn't a bit wet, it was soaking wet... and it had been fully cleaned when i did the headgasket job...

so the fuel blew by the rings, then pressurized the crankcase.... through the breather hose... in the intake, where it fouled the combustion

dropped the engine today , pita compared to the 911, it's out now , tomorrow i'll take the engine apart, probably won't have enough time to re-ring it then, +2 more weeks of walking to work... since i can't work on it during the week... luckely it's only one mile to work....i HATE walking...