Spark Plug  Exhaust Valve
My Spark Plug ... what do you    The holein my exhaust valve
  think?                                             That didn't help!

 

Deven WailesDana Wailes
 
Hi Tec Automotive
Anthologies of an Engine Rebuild -- Discovery and Opportunity #2

 JohnJackson




 Story and photos by Redwood Region member John Jackson


For anyone who read my last piece, you know that my '87 Carrera developed a cough and loss of power on Redwood's All About the Roads tour.  I'll continue where I left off last month...

What would you do next? Where or who could I turn too?  My trusted Google of course. Google always has an opinion, and for my situation and symptoms, they suggested a tune up and valve adjustment. Unfortunately my use of oil during the last 30k miles and finding oil on a spark plug suggested something much more complicated.

I questioned members of our Club and each time a new tech was suggested, always with the usual high praise. Apparently there are many qualified Porsche shops in Northern California. I decided to give my situation extra consideration, I needed to find someone who could service, advise, and in the worst case, rebuild my engine.

Eight years ago my lovely wife thought it would be cool if we had a classic Porsche. When something like that happens, you make sure you don't make a sound, don't act excited, just quietly acknowledge her suggestion. The very next day, my search was on (quietly). I stopped by a local Porsche shop to get their opinion on classic Porsches. The staff there, after a few questions like how much did I want to spend, suggested several choices. '87-'89 3.2 Carreras were one of the sweet spots suggested. That advice is one of the reasons we own a '87 Carrera today.

During that meeting, in an adjoining room, one of the staff was assembling a 911 engine from a box of parts. Seems like someone with questions about its assembly brought him that box. Easy to take apart, but hard to put together! Apparently these guys had been in business before my '87 had even been built. A good reason to benefit from their advice. Those guys were Deven Wailes, the owner, and Dana, his brother, of Hi Tec Automotive.

The results of my "tune up"...

When do you need your engine rebuilt? A two part series published by Pelican parts suggests:

     If you get less than 500 miles per quart of oil
     If you have ZERO compression in one cylinder
     If your spark plug, or plugs, look like the one the photo (see photo)
    
And if your engine coughs as if it were a 5 cylinder model

There is a good chance you need a engine rebuild.  I had all four!

A way to see what is going on inside your combustion chamber, i.e. reading spark plugs, according to the article, Time to Rebuild by Pelican Parts: "If the plug is wet with oil, that indicates that there is significant leakage into the combustion chamber, passed either the valve guide or piston rings. This is generally a bad sign and an indication that your compression test may not yield good results."  It did not. 

The famous "Might As Well" Interview...

My Choices -- the interview with Brad d'Alessio, Manager, Hi Tec Automotive:
   

     1. Take the car home and display it as largest model car in the neighborhood.

     2.  Sell it for ??? $$$
     3.  Buy used engine, upgrade to larger engine, or rebuild existing engine.


I chose to rebuild. "And while we have the engine apart we might as well

The studs (see photo): Steel retaining studs were used on the inlet side of the barrels and Dilavar studs on the exhaust side to allow for differing rates of expansion. These studs were used in an attempt to match the stresses of hot and cold on the 1978-89 aluminum engine cases. Unfortunately the Dilavar studs did not hold up -- they have been known to break off in the engine. Raceware studs with increased tensile strength are the current recommended replacements. I've always wanted a race engine.  Spark plug wires:  Because they are 20 years old (of course).

Powder coat the engine cavity and parts: An environmentally safe coating that last several times longer than paint and protects against rust and corrosion. Wouldn't want the new engine to fall through a rusted body and think how clean it's going to look at the next concours.  

While I wait for my engine to be polished, deconstructed and reconstructed, I share with you some of the research as to why I had an opportunity to rebuild my engine.

In the August 2004 issue of Excellence Magazine, it's the opinion of Mike Daino of Powertech, that Porsche changed the tolerances in later 3.2 engines making them tighter. He speculates those changes may have contributed to an oil starvation problem that ultimately causes premature wear.

Russell Lewis in his Porsche Carrera 3.2 article in October 2006 911 & Porsche World wrote: problems can result from stop and start motoring allowing unburned fuel to wash oil away from the valve guides and piston ring areas causing a high rates of wear.

Ted Robinson of German Precision and Dwight Mitchell of AutoSport Technology suggested that the wear is caused by the Viton valve stem seals used on the 3.2 engines. The theory is they work too well and prevent the guides from getting adequate lubrication causing the intake valves and guides to prematurely wear out. This wear can show up at 40-60,000 miles, by then the valve stems seals themselves have also worn out and the engine will have excessive oil consumption, plug fouling and all the rest.

Additional research found that Porsche experimented with metallurgy for the valve guides. As they ran engines hotter for emissions reasons, or more power (creating more heat). The metal starts to show more wear. They did eventually switch to harder manganese bronze guides. The valve stems seals can either be Teflon or Viton. Some say Teflon seals too well not allowing enough oil and lubrication to the valve stem.

Actually, I was just unlucky. I think a piece of carbon dislodged from that dirty fouled spark plug and got lodged in my exhaust valve.

                                 PHOTOS OF THE FINISHED REBUILD NEXT ISSUE

Drive safe and fast, but  do not exceed the speed limit! Thanks for following my adventure, jj 

Part 1
Part 3
Brad d'Alessio
Studs

RacewareRaceware
Valve guides, stems and caps:  All Raceware suggestions.


engine