99 996 with 109k. Engine died at idle, wouldn't start again. Turns over such that the motor is having valve interference issues. No oil under the car at all.
Oil pressure at idle was running fairly low, with the dreaded white smoke cloud at high rpm.
My conclusion: timing chain tensioner dropped, allowing one chain to skip a tooth. Since this is a fairly high milage motor, with low oil pressure, I'm going to overhaul it.
My question: As an aircraft mechanic, I think that the in house overhaul would be the best, most cost effective way. Since I've not overhauled one of these before, any suggestions? I'm looking for a good source of the parts, services, and materials needed. Also, any recommendations for a rebuilder in the SE US? (Just in case)....
Thanks

 

Kbollaert, welcome and I see you are a paying member. Thats the first step.

Its probably no more complicated than any other engine you have worked on. At a minumum, get the Bentley manual, read all engine posts here and Renntech.org (also become member there). If you have many $$$ in tools (which Im sure you do), and a good work area, you will be fine. Its obvious just from your post, a teardown/inspection is needed.

Read and study everything you can find on the engine and how it works then the light bulb will go off. I am not a pro-mechanic but have an extensive mechanical background. I am confident I can do anything on my engine short of actual machine shop work.

Listen to the experienced guys here, laugh at the ribs and jokes, then DONT GET IN A HURRY!

Oh and I almost forgot. You MUST post some pics or no one is allowed to help you. (1st joke) but please do post pic.

 

You should consider talking to this fella about his Duremetric cable as long as it has at least one vin left. Enthusiast cables will do 3 then I think Durametric will let you buy more.
https://rennlist.com/forums/996-foru...-for-sale.html

http://www.durametric.com/default.aspx

Your white smoke may have been a bad AOS or cracked head.

 

Thank you. I have the Durametric cable (lifesaver!) Pics will be posted.

 

You are in the southeast?

Call Jake at Flat 6 Innovations in Georgia.

 

As far as stock parts most on the board would probably use Sunset Porsche or Suncoast Porsche. They give a very good discount.
Jake Raby Flat 6 ( http://www.flat6innovations.com/ ) and
LNEngineering ( http://www.lnengineering.com/ )
Are two that have modified and re-engineered parts that have shown weaknesses
Hartek in UK has also written extensively about these engines.
There are a couple of folks on this board that have documented partial and complete rebuilds.
Logray is one
https://rennlist.com/forums/996-foru...he-finale.html

Dharn55 was one of the first to repair a cracked head.
https://rennlist.com/forums/996-foru...-repair-2.html

 

Pelican parts had all the parts for my 996 project. Mine had a jumped timing chain and some bent valves. Did all tge reapirs alone, in my two car garage, using home made locking tools. Have a complete write up on the Canadian forum. Look under "Dragged me home one of these".

 

Sorry to hear about your situation. The Bentley manual is good but doesn't have full engine building info - you'll need the CD manual that you can find online. You'll also need a few specialty tools, (or fabricate them) depending how deep you go. Look for logray's rebuild here on Rennlist as fpb111 says - a great resource with lots of pics and info. The big thing with these engines is the proper assembly sequence - other than that, it's just an engine. I think with your aircraft background you are probably going to be fine. Take your time and take lots of pictures to help you re-assemble. Lots of suggestions on this forum for parts suppliers - I've found Pelican to be good. Good luck and let us know how it goes.

 

Many thanks for the great info! I've been a lurker since my first Porsche (91 Targa), and have always found this to be the best source.

 

Very sorry to hear about your engine failure. If you are in need of assistance or interested of rebuilding your engine with high performance parts, we can gladly assist you.

Bisimoto Engineering carries an entire line of custom high performance forged aluminum pistons in which can be tailored to your choice of bore size and compression. Along with forged steel rods to handle greater cylinder pressures and rpm at very reasonable pricing. Kindly give us a call or email for additional information on all available Bisimoto products and services to get your vehicle up and running stronger than before!


- Julio A.

 

Update:
After tear down, I found the 1-3 intake cam broken between 1 and 2 lobes. Every valve was bent, but I didn't see any obvious cracks around the valve guides. The pistons were marked, but not enough to replace, unless I find damage when I dye-pen inspect them. The cylinders are not damaged, and seem to be in good shape. The crank seems to be in great shape, but I'm going to get it mangafluxed to be sure. The water pump that I replaced LAST year is now sans the impeller blades(?!). One of the chain guides is worn, but I'll replace all of them anyway. Overall, I'm pleased with the condition of this motor, even with the damage that it has. Pics will follow soon ( really!).

 

Wow, that's a new failure mode for me, a snapped camshaft. Curious your impeller blades are gone too.

I wonder if bits of your impeller blades got caught in the head passageways and caused an overheated condition? Heat might be a factor in low oil pressure. Lost plastic impellers have been attributed to cracked heads.

Or you skipped a tooth and bound a valve and sheared the cam as you thought.

Can you post a pic of the broken cam?

 

Sorry about your engine failure. It's good that you're an aircraft mechanic
Just wondering how long have the low oil-pressure and smoke issue persisted leading up to the failure?

 

Was the water pump OE or an aftermarket brand? Looking forward to the pics and the updates!

 

With finding a snapped camshaft, did you notice if the cam holders or caps were torqued to the right specs?

I've had a broken camshaft before on a different car due to previous owner tinkering with the engine and not torquing everything down correctly.