Smoke on Start Up - Question
 

I have "the book" and read the starting chapter on "When to Rebuild" and still have a question. I have an 86 Carrera that blows a fair bit of smoke for about one to two minutes after start up. The only other symptom is that I get a nasty gravely sound out of the motor with black smoke if I step on the throttle and the engine has not been thouroughly warmed up (i.e. the hour drive mentioned in the book). Anyway...the option given in the book is essentially all or nothing. What about just rebuilding the top of the motor? In my area(San Francisco Bay area) I am told to expect $10K for a full rebuild. The car is only worth about $10K. As an aside, I have plenty of oil pressure (5 bar at 3000 rpm warm). I still need to do a leak down and compression test. Oil consumption might be a little high, but i have not quntified it yet. Any advice would be appreciated. Thanks.

Describe the gravelly sound. A more detailed description would help a lot.

The smoke is likely from worn out valve guides. The gravelly thing though, sounds like it could be anything from a failing chain tensioner, to a broken head stud depeding upon what exactly the sound is.

Yes, a top-end only is very doable, especially on a Carrera.

$ 10000.- for an engine reb. on a runnig engine???? you must be kidding!

harold

More on gravely sound
 

Well, it only happens when I really step on the throttle and the engine hasn't been running for long...say under a half hour. It comes on quickly, and the moment I let the throttle out it stops and the black smoke stops coming out the rear of the car. It sounds like someone shaking a can full of small grains of metal or sand really fast. Not a good sound...that's why I let out the throttle. I drive this car every day.

As far as cost of rebuild, $10K was the average. some said $8K, others said $12-$14K. I think the high end guys were quoting replacment of pistons and cylinders. I am getting quotes of 3500-4500 for top end rebuild. That's just the way it is in CA.

Sounds like pinging. (detonation) Could be caused by lots of things, including the most obvious. Too low octane of fuel. Could be it has a chip with an aggressive timing curve. Carbon build-up. etc. etc.

I think my 82 911SC targa with 144000 miles is doing the same. About 3000 RPMS when I throttle down this CRACKING noise is heard also loss of power oh and so smoke. Wayne thinks it's to be a exhaust leak caused by a broken head stud. My feeling are with you