TONS of SMOKE!!!

[jpryma]

I've recently bought a 1970 911 targa. I dream come true. It was in dreadful shape when I got it. It would start and barely run. Carbs were in desperate need in of rebuild so for the past few weeks I've been waiting on parts and finally got them working today. Sort of...

I dialed down the carbs to a minimum of backfire through the carbs and tried to get it to go around the block...It started to produce some smoke through the exhaust at the start but after about 3 minutes it was bellowing HUGE clouds of smoke throughout the neighbourhood! Oops.

I am hoping it is not too serious. I seem to have good compression but my understanding of this kind of engine is at a novice level. I have done all kinds of valve seal replacements if that is what the problem is but the VOLUME of smoke seems to me to be something else. My thoughts are there is a problem with the oil vacuum system. Any assistance with where to learn more about the system would be appreciated...or suggestions of where to begin.

[Lyle O]

First thing to do is check how much oil is the system. To check the oil properly, the car needs to be fully warmed up, running, and on level ground. On the dipstick, it should be no higher than the middle of the range shown. With too much oil in the system, it feeds into the intake via the breather hose and goes right into the combustion chambers...hence a billowing cloud of smoke. Overfilling of the oil tank is a very common error for those unfamiliar with aircooled Porsches. If the oil level checks OK, then you can start looking at valve stem seals, guides, piston rings (via compression and leak down tests), etc. But check the easiest possible problem first...there are many good articles here in Pelican on the topic; do a little reading (look at the tab above titled “How-to Articles”, and use the search function in the forums). Good luck, and welcome.

[targa72e]

Advise above is very good. Over fill is common. Also if the car has sat for a long time the rings can stick. When such a engine is first started it can pump lots of oil into the muffler. When the muffler gets hot you get a big smoke trail until its burned off.

john

[jpryma]

Thanks Guys. Sorry for the late reply. I didn't get notifications that anyone had heard my pleas for help. I Checked the oil and it is in the mid range of the marks. Also the breather hose isn't attached? I don't know where it should go as I haven't been able to compare it to any Porsche engines from this era. The smoke only happens when the engine is working hard and producing heat, so I suspect the muffler is full of oil that is starting to burn. The stuck rings would make sense.

I am now at the point of dealing with rebuilding the brake system, ordering replacement hoses (Can't find any in Canada so I am ordering them from here). I took a hose of today and sure enough it wont let air through so I'd say they are pooched. The master seems to be working well, so I am not planning on replacing at this point. I thought I would like to remove and inspect it anyway to see if it is also in need of replacing.

The Webers are another issue. the throttle shaft journals are worn pretty badly and need to be fixed before tuning can begin. So I'm a bit disappointed about not being able to go around the block but the upside is I know where I need to get to!

[mepstein]

Did you check the oil hot? It's not enough to just check it after 5 minutes of idle. It needs some spirited driving to be hot. If not, you will be overfilling.