Blowing blue smoke...

BWMURPHY · 06-25-2004, 04:24 AM

After 40K miles of problem free service my 87 911 has suddenly developed a smoke problem.

I left the car running with the A/C on full for 2-3 minutes at idle.
When I got back in the car, the temp was "straight across" but normal on the gauge.
I drove the car and had thick blue smoke. I stopped the car and opened the rear lid - the engine did not feel very warm.
There is not unusual noise or roughness. I drove the car more and the smoke poured out, then it stopped and I drove it a couple of miles home. I was able to get some smoke on heavy acceleration, none on engine braking. (I was suspecting a cracked ring).
The oil level is normal.
I let the car sit for a day, and it now blows blue smoke at idle, some what worse at 4000K.

I was hoping someone could give me some diagnostic advice - I haven't pulled the plugs to conitions or check wet compresson or valve covers to check the stem seals, as I am still hoping it is a crankcase ventilation issue.

Any help would be appreciated.

Brian

Noel · 06-25-2004, 05:46 AM

Did you just change the oil by chance? Mine has done this when I didn't use a funnel to refill and I spilled oil into the breather hose that connects to the oil filler pipe.

If not, then I think a compression and leak down test is in order.

dickster · 06-25-2004, 06:01 AM

wheres the smoke coming from?

i get a small amount from the occasional drip of oil onto the heat exchangers. nothing out the tail pipe though and nothing to worry about.

you may have a worse leak.

BWMURPHY · 06-25-2004, 06:09 AM

I did just add a quart a few days back, but I would have suspected that would have given me the oil on start-up.

I ran clean for a few days before it started blowing.

It initally blew a lot of oil (like a James Bond escape).

Now it is blowing like an old Rabbit with bad stem seals.
I'm just suprised it came on so suddenly, I believe once the motor was warm enough to open the thermostat to the oil cooler.

The oil isout of the tail pipe, it is not seepage on the exaust from the valve covers.

I'd apprecate any other ideas before I pull out the leakdown tester. I just don't (want to?) belive it is a cylinder issue.

Brian

dickster · 06-25-2004, 06:39 AM

mmm, maybe you did overfill?

what procedure are you using for filling?

*edited* i guess after 40k miles you;d know how to do it!!

Noel · 06-25-2004, 07:10 AM

Check the oil to make sure you didn't overfill. It sounds like you have had this car for a while, so I'll assume you know to only check the oil at operating temp with the engine running. I consider overfilled anywhere above the halfway point between the high and low mark on the dipstick.

BTW, I had mine smoking, it was also James Bond like, but when away after a few miles.

BWMURPHY · 06-25-2004, 07:13 AM

I was a 1/2 quart over on the filling. In this case, I did it cold without checking the oil. The car sits all winter in a garage, and it can usually weep a 1/2 quart over six months.

I fill usually fill it with a long funnel. This time I just poured from the cab to the outside of the filler.

It has always been a champ. I could see if I was beating on it or it overheated, but unless a valve stem seal cracked from age, I am at a loss. I am still assuming that somehow oil is being fed into the intake.

BWMURPHY · 06-25-2004, 07:16 AM

So Noel,
Did your's blow smoke right away?
Mine did a week later, but it may have been the first time it reached normal operating tempurature.

I sucked out a quart, I suppose I could suck out a few more.

Yes, I have had the car for almost 10 years, and I serviced it for the prior owner. It is not normally out of my hands...

Brian

chrisp · 06-25-2004, 07:47 AM

So what does the dip stick read when it's at operating temp (external cooler open)? I aks becuase you say you may suck out a couple of addtional quarts. I think smoke from overfilling only comes when the oil level is at or above the top mark. The gap between the two marks is around a quart if memory serves me right. So you've sucked out one already and this should put you somewhere in the normal range. If you pull out a couple more quarts you will be way too low for normal running.

BWMURPHY · 06-25-2004, 08:02 AM

Hi chrisp,

I have not brought the engine to N.O.T. since I brought it back home from the smoky drive.

When I last drove it, it was 1/2 quart over the mark on the sump.

Were I to run it to N.O.T. I would suspect the oil level is OK. The car usually runs in the low range on the Temp Gauge. When it got to normal it blew the smoke.

I am still suprised - if I overfilled it and it blew right away I could understand, why it blew smoke some days later I do not get.

I figured at this point, running a quart low at idle in the driveway would be OK, no high speed cornering here. I don't see the oil "burning off" however. Someone said the CAT could now have some oil in it and that it could be burning off from that.

I am apprehensive to take it out on the road and try to blow the oil out if it is indeed a ring or a stem seal.

Brian

chrisp · 06-25-2004, 08:10 AM

The weeping 1/2 quart seems like a lot to me. Where does it end up? Hopefully on the floor. That's a pretty big puddle. Imagine pouring 1/2 quart on the floor from a fresh bottle.

Was it 1/2 qt. above the lower mark or upper mark? At 1/2 above the lower mark it shouldn't be an overflow scenario.

Does it have the correct dip stick?

Early_S_Man · 06-25-2004, 08:12 AM

If the oil level is above the top mark on the dipstick after warming up ... you overfilled the oil and smoke is most likely due to oil blown into the air box and being inhaled.

Clean out the airbox as well as possible with rags and Brakleen or similar solvent/degreaser. Suction out at least 1 quart of oil from dry sump tank. I think that will end your smoking problem after an hour or so of driving.

If not, then the overfill is not the problem and a compression and leakdown test is called for ...

Noel · 06-25-2004, 08:19 AM

You mentioned that you have not brought it up to normal operating temp. The issue is that you won't know what your problem is until you properly check you oil.

BTW, mine took a few minutes to start smoking when I got oil in the breather line from not using a funnel. It would take several miles to develop smoke in an overfill situation due to the oil needing time to heat and expand. After hearing all of this, I'm convinced you have classif overfilling issues. Now you just need to confirm it by checking it at operating temp.

BWMURPHY · 06-25-2004, 09:18 AM

Hi all,

The weeping 1/2 quart over the winter is annoying, but it goes onto SpeedieDry. I haven't had the opportunity to overhaul any seals.

I was very lucky to get my kids and the 911 to still get to live with me after a divorce a few years back!

I have the same dipstick I always had - I will check the AirBox. I'd frankly be thrilled if it is full of oil.

That was my suspect, it aspirated oil and has been choking.
I was just fearful of running it if it did have a bad ring.

I will check the intake for oil, clean the Air box if it is a mess (I haven't cleaned an oil bath air filter in a while), and run the car to NOT and see where the level is on the stick.

I better do some night driving so the smoke screen is less noticeable....

Thanks for all the advice!

Brian