ALERT: Magnesium Oil Pump Case Failure!
Updated: Nov 4, 2022
The good news first: Kinninger Racing has a new home!
It was only a matter of time before Mark’s projects exceeded his available workspace so he teamed up with Ed Muscat from 'Ed's Coupes' and he now has a place to call 'home away from home'. While Mark’s efforts at Black Forest will keep him occupied performing service work on customer cars Monday thru Friday, his afternoons and weekends will be spent at 10227 Prospect Ave, Santee, CA, adjacent to Gillespie Field Airport performing restoration work and creating 911's that dreams are made of.
Here he will showcase his expertise at resurrecting tired, air cooled flat sixes into masterpieces that are just as at home on the concours grass as they are on the track or favorite back country road. More good news is that Ed has a quite a few donor chassis to keep Mark busy for the foreseeable future.
This new space allows Mark to keep multiple projects in work and, more importantly, provides safekeeping for all the essentials that go along with it. A veritable storehouse for 915/G50 trannys, 3.6 blocks, trailing arms, and all the you-name-its that bring these creations to life.
Kinninger Racing now has a footprint worthy of the artisan craftsmanship that
goes into every air cooled masterpiece. Visits are available and can be scheduled via email to see what Mark has up his sleeve to be showcased at an auction site or, better yet, in your garage as many are nearing completion and can be reserved with a deposit. Of particular note, they can also be finished off to specific customer requests that represent the individuality unique to long hoods and their owners.
ALERT! 964 3.6 Oil Pump Case Failure!
Search the World Wide Web for magnesium pump case failure and, surprisingly, this issue has not yet been linked to any crankshaft bearing failures. But while disassembling a 3.6 that spent a good deal of time on a garage queen then relegated to an engine stand without an oil change, Mark was stunned to find that the magnesium oil pump case suffered significant material deterioration to the point that the big-end rod bearing for cylinder 4 was destroyed by the particulates shed from the case (a dirty oil feed kills outermost bearings 3 or 4 first while starvation usually destroys the middle cylinders 2 or 5 first).
Mark believes that the M64 builds from ’89-’94 subject to short drives and longer term storage are the prime candidates for magnesium oil pump case deteriorating due to the condensation that develops during warm-up but doesn’t get evaporated at higher temps during an acceptable warm-up period. This moisture dissolves in the oil and the magnesium oil pump case now sits in conditions ripe for material deterioration. A quick refresher on material stability notes magnesium being the most susceptible to shedding valence electrons thus begins the process of ‘corrosion’ (of note, no mechanical engineering PhD’s here so we’re hypothesizing on how this occurred. Mark has also subsequently seen it now on another 964 engine).
While Mark cannot specifically point to the direct cause (i.e. poor pump plating/protective layer, etc), he believes a major contributor worsening the problem is acid. Yes, acid. This comes from the sulfur in the gasoline getting oxidized and turning into sulfur-trioxide. Hence another risk from condensation in your engine case: the sulfur-trioxide condenses with water to form sulfuric acid!
The good news is that we normally don’t see ill-effect from this on our daily drivers due to the more frequent oil changes and infrequent starts simply to rearrange the stable (remember- this is why oil should be changed annually even on the garage queen if the car has been started). Add operating temp to this equation of moisture in solution with acidic content and the magnesium oil pump case deterioration occurs at an exponential rate.
So along the lines of a photo is worth 1000 words, here’s what the first deteriorated oil pump looked like after Mark disassembled a 964 3.6 donor motor. See those pieces of metal that fell off just by repositioning it for a photo? Yikes!
“So if I own a 964 motor that has sat for more months than I’d like to admit to, what do I do?”
Mark strongly recommends sending your oil off to Blackstone Laboratories for an analysis to see if you have excessive magnesium content (Blackstone notes average magnesium content of 151 ppm as it is an oil additive that helps keep particulate suspended in the oil so the filter can trap it). And if you do have too much magnesium, a high copper content could mean it's too late. Your rod bearings might have seen better days.
The silver lining to this news, of course, is that a 3.8 rebuild could be in your future (and both your significant other/CARB can be none the wiser ;-)
As for the bottom line, this simply means to get out and drive more. Do your very best to drive for at least 30 minutes before relocating your precious steed in the stable.
With healthy exercise and yearly oil changes, your 964 engine will continue to deliver all the smiles per mile that can only come from a flat 6 and 3 pedals.