Kevin,

So to sum up, and your post-mortem here has not only been honest but extremely instructive:

1) Thermostat bypass sent all oil to filter housing
2) Filter collapsed blocking flow, resulting in main bearings stroking out.

I am still unsure as to why precisely the factory added the 964 turbo oil flow restrictors, I've never heard a definitive factory source say why. We do know that Bruce Anderson has a view:

http://forums.pelicanparts.com/porsche-911-technical-forum/608132-cam-tower-oil-line-restrictors-redux.html#post6016706

http://forums.pelicanparts.com/porsche-911-technical-forum/255525-tubo-oil-pump-xlitres-per-min.html#post2286509

Ah, see fellas like you are very helpful in these sorts of instance. Sums it up in two very good points.

1) Yes. The t-stat bypass forces oil to the oil filter housing. "Cold" side is permanently closed.

2) Yes. I agree with the assessment that the filter collapse was most certainly caused by bearing debris blockage.

Some points of clarification are in order.

1) was a contributing factor only when the oil filter housing was installed. Upon removing the filter housing to re-install the oil cooler, I also re-installed the t-stat in the engine.

2) actual collapse was only on the large oil tank filter. The small filter on the engine never truly collapsed. It just deformed inward a bit. I suspect that was caused by cold startup. And note that when the large filter collapsed, the small filter was then out of the picture and the oil cooler was back in place.

Kevin,

I thought I understood, but now I am confused.

You're saying that you ran the car with the RSR bypass and external filter/cooler setup, then switched back, THEN it stroked?

And the large filter collapsed? But the large filter is in the scavenge circuit-- the scavenge side picks up oil, pushes it through the large filter and it falls into the tank. From the tank, it flows by gravity to the inlet to the pressure side of the pump.

Are you saying the large filter blocked, causing the inlet to the pressure pump to run dry, and THAT stroked it out?

Not trying to be obtuse, I'm just trying to understand the precise chain of events.

C, Correcto on all points in your sentence

Yes the large tank filter collapsed. I don't disagree with anything else in your assessment in the above quote.

I don't think the large filter was fully blocked. Oil flows from outside-in on the filter. So even though the large filter was seriously compromised, it could still flow oil. Therefore the pump was not starved entirely of oil.

After returning to my paddock space, I could fire the engine and the gauge would show pressure. So the pump was taking in and distributing oil. I was actually able to quickly drive the car on the trailer.

Damage was already done, so what the hey why not. Not saying I didn't do more damage by doing that. But it was already cooked anyway. That being said, lesson learned. Future incidences (hopefully none) will be parked on the track out of harm's way. Tow me in and i'll winch it on the trailer (winch being one of the offseason trailer maintenance/upgrades)


Yeah don't be obtuse or i'll throw you in solitary confinement (obtuse = reference to Shawshank Redemption) :D No offense taken. I appreciate the time taken to analyze the engine failure. SmileWavy

Hoorah Web Cam
 

Whoever Web uses to repair the cam bearing surfaces (for some reason Web only does the lobes/profile) gets a thumbs up from me. Cams went from looking like this

http://forums.pelicanparts.com/uploa...1348504831.jpg

to this

http://forums.pelicanparts.com/uploa...1353104975.jpg

$366 later i'm back in business on my cams.

To an earlier point (a winch on the trailer), I purchased an inexpensive (less than $100) Harbor Fright winch. I think it was advertised for ATVs, so they could pull themselves out of the troubles their riders got themselves into. However, it had a 50+ foot cable (needed for my two car trailer) and a wireless remote control. It is so small that my tool chest (which rests on larger pneumatic tires so has more clearance underneath) fits under the chest at the front bulkhead of the trailer floor. I wired it in, and it works great when its only task is pulling a 2,500 pound or less 911 up the tailgate and in.

Previously I used an equally inexpensive (15 years ago) portable winch which was bulkier and didn't have the cable length I needed, so the workarounds were a bit irksome, and I had to get it out to use it, and so on.

So I am very happy I didn't buy a $400 hefty winch for permanent mounting, and sorry I didn't twig to this kind of winch sooner (though its ilk may be more recently on the market, and the prices may have been coming down). Though the main impetus was an impending change to a 5.5" clutch, which ought not to be slipped. I am loathe to commit to a relatively high speed, one shot run into the trailer - with my setup, too many tight spots and variables.

And yes, it took me too longer than it should have to realize that one ought not to limp a car back to the pits after a "bang" or other sour sounds from the motor.

Thanks for the the recommendations on the winch Walt. Recently found a source for a nicely priced new 2000 lb Superwinch- less than $100 with remote. I'm all over that deal like flies on sh..........

BTW its always good to check your oil pump.

http://forums.pelicanparts.com/uploa...1354043339.jpg

Of course this is obvious when you have a mega disaster like I did. But my point is that this pump could have been passed off by someone with no shame as being a good useable pump. Reason I say that is because the pump spun freely and gave no indication of damage inside Surprising, I know. From an outward appearance, the screen was clean and there is no scoring on the pump rotors visible through the inlet and outlet ports.

So any time you buy a pump of unknown age and source, I highly recommend opening it up. You never know what you may find.

Kevin,

What can you do with a pump like that? Can you have the case bores refinished similar to the cam? It might require some coating to build up the walls, bt then you should be able to machine it out. Those are non-contact surfaces, right?

I wonder what the pump would even do as is? So anyway, what are your plans for a "new" pump?

I don't know that you can do much of anything? Probably more expensive to resurface it than it is to replace with another good used one.

You're right that the damaged area is non-contact. I don't know if the same outfit that did the cams could restore this magnesium. I actually don't know who Webcam used. They sublet the work to someone else for the cam bearing repair.

I've already got a "new" pump on hand from Joe Shukys (ShakinJoe) so i'm all set there. Just need to track down a crank and i'll have all of what I need to get the bottom end back together- after I send out the crank and rods to be balanced.

I also have to finish up the case mainweb smoothing with my long reach carbide bur (poor man's boattail windage improvement) and then clean it all up. Probably going to break down and pull all the piston squirters too. I just don't feel comfortable trying to flush them in-situ. Seems like it could be a pennywise decision to do that, after what i've been thru already.