73 911 2.4L CIS bad smoking problem!!!

[confused]

Smoking Problem

Hey guys, I have a weird problem on a 1973 911T Targa with a 2.4L CIS engine. So the car has been sitting for 10 years. Oil changed - filled to proper level (I sure don't think I over filled it). The engine fires right up every time. Takes about 1 min or so then it starts smoking heavily!!! Oil pressure on the gauge looks great! Engine sound normal, no exterior problems.

Every time = the engine starts then after a min or so the engine dumps smoke, lots of smoke, not a small amount - the smoke is so dense that it will probably kill all the plants around my garage - thick dense smoke!

I don't think it is any type of guide or ring problem - wouldn't these problems cause smoke immediatly. Wouldn't the plugs be fouled? Engine sounds fine, no weird noises. The engine then drips oil out of the tail pipe. A slight dribble, there is a small puddle of oil under the tailpipe about the size of a silver dollar.

How could the exhaust be full of oil!? !?? Anyone have any idea of what is wrong? I am going to do a compression test tomorrow.

Thanks for any help.

[CRH911S]

try pulling the cover off the air box and look under the filter for signs of oil.
Clinton

[ruf-porsche]

Do you remember how many quarts of oil you put into the engine?

Do you recall how much oil was drain from the sump and oil tank?

Sound like you might had overfilled the engine.

[artisticent]

Hey Confused.
I would like pics of your car, Im thinking of buying one but its torn apart.
It has a sunroof, not sure of its value.
Thanks
Nathan

[Early_S_Man]

Forget the airbox!!! The problem is oil collected in your muffler!

Pull the muffler, dump the oil out and let it drain overnight, then clean as best you can with Varsol or similar solvent. Let muffler air out for a couple of days before refitting. Then, a good two-hour drive to heat up the muffler and burnoff the residual oil will solve the smoking problem!

[confused]

Thanks for the help guys

Early_S_Man, I am leaning toward that being the problem. There is definatly a large amount of oil in th exhaust itself.

ruf-porsche, I just drained th old oil - I don't remember how much. I filled it with 9 quarts. There may have definatly been a problem with overfilling in the past.

CRH911S, I don't think it could be the airbox unless someone poured a quart into the airbox - there is alot of oil - the smoke cloud is super thick! The plugs woulc have probably fou;led.



By the way the engine sound great, no noises, sounds like it has all the power it should, no missing, no sputtering. Its just a oil burning problem. I am going to do a compression test (mostly for curiosity) and then remove the exhaust to see whats up.

[CRH911S]

I suggested checking the airbox due to the statement, "...filled to the proper level." Oil in the exchangers is a strong possibility due to the fact the car has been sitting so long. I agree with Warren Hall.

[CRH911S]

opps, did the 73.5 have exchangers?

[lyon]

Sounds like an overfill to me as well. I did that the first time changing my oil on my 911.
I still have a bit of smoke coming out of my exhaust.
What are the major dangers associated with overfilling?

[t6dpilot]

FWIW, I have a smoke system on my aircraft and it pumps special oil into the exhaust pipe to make that beautiful thick smoke for airshows. It sounds like your problem is oil gathering in the exhaust pipe or heat exchanger. The burning question is why is there oil in the exhaust? Hopefully, there is not something that requires you to pull the motor apart? You said that the plugs are not fouled?

[Early_S_Man]

Scott,

This is a normal situation for any older 911 that is left to sit for months or years. Th oil level rises in the sump, and consequently, in the exhaust valve cover chamber, too ... to the point it is above the exhaust valve guide in the exhaust port. Oil seeps past the Teflon valve stem seal and up the valve guide, and drips into the port, and down into heat exchanger, ultimately collecting in the muffler. When the engine is started it takes a minute or so to heat up the muffler to the point that smoke is generated, hence the time delay.

Some people mistakenly state that the oil is leaking past rings, but oil collected in the combustion chamber would cause instantaneous smoke, not delayed by a minute or more! The 'classic' 911 'puff of smoke on startup' is the result of oil in the combustion chamber. This is not what is happening in this thread!

[t6dpilot]

Yes Warren, I deduced that it was not oil leaking past the rings. I am aware of what the thread was about - what's up with the "!"? I was just adding my $.02 regarding the heavily smoking exhaust. Basically, I was supporting the theory of oil in the exhaust/heat exchanger - it is the same thing that happens when I fire up the smoke system on my T6, except that is a continuous flow (gotta love a kick a$$ smoke system).

I appreciate your comments about the oil and its route through the engine into the heat exchanger. I would not have guessed that you would have such oil accumulation from a healthy engine - I was hoping it was not terminal for him. For us who are new to the early 911 ownership game, we appreciate the information that knowledgeable early 911 guys like you pass along. Thank you, as I learned something new today.

[confused]

Warren, I think you are dead on. The heat exchanger to muffler flange has oil drips hanging from it. I pulled the plugs today - no fouling - just running rich. By the way the oil level was very very low when I first got the car - i guess all the oil went into the exhaust. The car sat for 10+ years.

A smoke system in a plane is very cool, a smoke system in a 911 is not cool - you should see my neighborhood the other day! If anyone was home and outside they would have hated me. Smoke everywhere. However there is alot less smoke when started today. Maybe I should put it back on my trailer, take it to a derserted area and run it till it burns out, what do you think?

I could either:
A. remove the exhaust, hopefully not break a stud, then replace all the gaskets, clean out the system

B. take the car far away and run it till it burns off the oil, although I am concerned about burnt oil deposits.


Oh by the way, this is not a first Porsche. I have 5 on my property at the moment and another 6 at the dealership I work for. Porsche crazy! I don't have tons of experience with these early magnesium motors. I have done lots with Alloy engines.

[CRH911S]

Option A, the environmentally responsible option. Replace the studs as needed because that is part of the reason why many of us own older Porsches. I know it's a pain-in-the-$%! but it will free up your conscious for more important things.
Clinton

[confused]

I guess any previous contributions to environmentaly focused organizations would be negated if I fill the local natural medow with burnt oil smoke.

I see some rust on one of the heat exhcangers, I have another good pair of exchangers, good reason for removing the exhaust.

Here is the car: