White Smoke from Engine Bay

l4nc3r · 06-10-2009, 04:29 PM

Ok, my dads old 87 924S has been sitting in our garage for years now. Been trying to figure out what happened. Here is the story in less wordage.
1)Sat for years
2)Drove, white smoke filled cabin. Took home immediately. All fluids were fine.
3)Tried to drive again that day, balance shaft belt shredded on us.
4)Replaced balance belt. Car would no longer start.
5)Sugar substance in tank. In tank filter clogged. Changed intank filter, fuel pump, and fuel filter. Also cleaned tank as good as we could.
6)Car would only start if spraying Starting Fluid in intake.(Yes, fuel pump doesn't prime unless started, need to jump it)
7)When started on starting fluid, white smoke came back. Smoke came out exhaust, and near the exhaust header. Car ran for 10 seconds then died.

Not sure exactly what it means. I don't know whether the sugar substance in the gas tank made it to the engine, or if the head gasket is blown, or if I just need to jump the fuel pump and let it clean out it's system. I was young(15) back when all this happened, and after owning 2 RX7's, I know quite a bit more about cars, yet still haven't looked at the Porsche.

Also, there was quite a bit of oil in the air filter housing when removed. Not sure if PCV valve is gone or what is up. Any ideas?

Techno Duck · Techno Duck's Garage

No PCV valve on these engines. Oil in the air box is usually o-rings on the air oil separator (oil fill tube). The crankcase vent that connects to the j-boot will spit out oil if there is a vacuum leak as a result of these o-rings.

I would start by replacing the DME relay or jumping the fuel pump.. you can run it directly off the battery if need be. White smoke could very well be a blown headgasket (if its out the tail pipe).. but sounds more like an oil leak if its making it through the vents in the car. Check around the cam tower, specifically the rear cover / hoist ring.

May consider replacing the timing belt while your at it.. sounds like the belts on the car are pretty old and a broken belt will likely bend some valves.

carlege · 06-10-2009, 07:47 PM

i was told that sugar would ruin your fuel lines and or engine. the sugar crystallizes in the fuel lines causing major blocking. Hopefully that didnt happen

nynor · 06-10-2009, 08:52 PM

sugar burns very hot and will destroy your engine, cracked head and/or cylinders. or so i've been told.

l4nc3r · 06-11-2009, 06:01 PM

Yea, I decided yesterday I'm going to replace the belts before I take the car out at all. I'm also going to have to jump the fuel pump. If sugar did in fact make it up the line, I guess some compressed air can hopefully take care of that.

Another thing I forgot to mention. When I was trying to crank it one time, it backfired out the intake. Popped the hosing off the AFM. A friend said the timing might be off?

I'm sorry, most of my engine experience is with rotaries, so a piston engine isn't my specialty. Thanks alot for your all's help. I greatly appreciate it.

Arizona_928 · 06-12-2009, 12:01 AM

The smoke is most likely coming from a bad cam seal gasket. It leaks oil onto the headers, and creates a nasty smoke screen! I would do a leak down, and a compression test as well, rechecking the timing..

Best of Luck!

Ctan · 06-12-2009, 12:35 PM

I had that problem too. it was the Cam housing gasket (~$14 new) and 3 hours labour. If you're replacing it yourself take the initiative to buy a new distributor button as the bakelite ones tend to shatter coming off the shaft.

OK-944 · 06-12-2009, 01:02 PM

You mentioned that this car had "sat for years." Could the "sugar like substance" actually be condensed old gas? Perhaps this is what's clogging things up? Perhaps you should address, in addition to the tank, the entire fuel delivery system (pump/filter/lines/injectors/fpr). And are you thinking "sugary substance" because of a sweet smell which accompanies the white smoke? If so, then you're likely looking at a head gasket issue...especially if you can also see/smell this from the exhaust. Just a few thoughts!

OK-944 · 06-12-2009, 01:03 PM

ps...keeping in mind that coolant emits a sweet smell as it burns.

l4nc3r · 06-15-2009, 06:13 PM

The Sugar substance is gone. I cleaned out all the lines and tank and got new pump and filter. Might have been old gas.

I will do a compression test on the engine. What should it be around for reference? I know a rotary is ~90 per rotor side. 120 for this engine?

And Ctan, yea, I will most likely replace all gaskets up top and belts. Thanks for the name of the gasket though. I'll get it!