I have a 74' 2.0 running Dual Dellorto DLRA 36 carbs. I just got my car back from my Porsche mechanic and I haven't had a chance to report back to him how it is running. I figured I would check with the experts until I can speak with him next week:

The car started great and runs great except that when I really punch it in 2nd or 3rd gear - at the moment of shifting, my wife (driving behind my car) says there is a puff of white smoke that is releasing from the exhaust. When I just resume normal driving or shifting without punching the accelerator before shifting, there is no exhaust plume. I am wondering what you guys think may be causing this?? Here is what was serviced on the car in the case that you think that the problem could be related to the servicing:

I had him remove the oil temp sending unit and replace sealing washer, housing o ring and housing gasket

He removed oil sump screen and cleaned - replaced the gaskets and sealing washer

Removed rocker assemblies and push rod tubes replaced and resealed all

Adjusted valves and replaced gaskets

As you can see, nothing was done to the carbs which is what I think you guys are going to say is probably the problem but because of all the oil that had leaked prior to sealing up the leaks I thought there's a long shot that there could be some correlation so i shared. The car runs great with no apparent back fires that I heard on this first 1/2 hour test drive.

Black smoke would be carbs, white smoke would be oil.

MAybe lol residue from the leaks? I would drive it for a few more miles to see if it goes away .

In most cars white smoke would indicate antifreeze and a bad head gasket. Not most of ours, of course. If I understand your description correctly, that there's a little puff right when you shift and no other time, it sounds like worn valve guides. When you're accelerating there's pressure in the cylinders, then when you lift to shift that switches to vacuum and will pull any oil that's between the valve stems and guide into the cylinder, where it will burn with white (bluish) smoke.

If that's the case you should be able to re-create the conditions by just lifting from the gas on a long downhill slope but leaving the car in gear. The "puff" will turn into a prolonged but thinner exhale of that white smoke.

He had to drain the oil to do this work. What weght oil did he replace it with? It may be a thinner ol slippng past the rings under high vaccum, similar to the above valve guide suggestion. Seems the oil change is catalyst for the problem.

My car does the same thing. Only time I can actually see it for myself is on a long downhill in 3rd gear with my foot off the accelerator. Other than that, fellow teeners have mentioned it to me on the runs. All have said valve guides.

What's behind you is in the past... Move on and don't let it concern you. But check your oil often...

OOooohm... The Zen answer

+1 ......... either too thin for the age of the guides or possibly overfilled.

1- Did he remove the valves themselves and mark them to put them back in proper location?

2- The same goes for the lifters and valve top-end?

3- Did he use an oil flush method that loosened up all the old varnish that may have existed in the motor prior? - important because that stuff usually develops a pattern in the way the oil flows- cleaning or flushing changes that flow geometry, so to speak

4- If more than 2 of the above, then your valves need to reseat a bit to find their new home, IF the valves weren't pulled and placed in different guides

All the responses are along the same lines, waiting to see how she breaks in. Keep tabs on your oil loss and let us know. There are different thoughts around running break-in oil at this point for the next 200 miles and then change it out, probably fewer miles. Then swap over to the recommended weight.

Run her below 4000 rpm for a bit and see how she responds...

Good Luck,

Wingnut

20/50

He did say prior to doing everything that I needed to run it for about 100 miles or so and then change the oil and filter again. Then do that again after another few hours of running it. Then by the third time, Most of the crap should be out.

Thx!

Sounds like a coolant leak.



A puff? Big deal. Most 914's "puff" a little smoke now and then.

Synthetic or Dino?

Dino

water in the fuel

Sounds like a oil ring to me. Valve guides usually puff smoke when you start the car. The decel is pulling oil past the rings.

+2 ..... that is also true

What kind of oil was used? synthetic?

I had some the samething happen to me , driving on fwy , doing 70 , smoke
coming from engine . it turn out to be PVC valve. put in a new pcv valve no more smoke. i do have fuel injection on my 2.0 engine . hope this helps.

No .....Dino

Worn valve guides, but until you are burning a quart of oil every 500 miles, drive it like you stole it.