Engine Bearing Failure- Disassemble Heads Too?

[KTL]

My fresh engine took a crapper after the engine mounted oil filter (full flow) apparently starved the crank of oil. That was a nice "upgrade" I chose to do......

So I certainly understand that the engine requires a COMPLETE cleaning down to the very last nut & bolt. Just wondering if the heads can be sprayed clean, or is it advisable to remove the valves as well? Everything else will be diassembled as much as possible- case & crank plugs removed plus piston squirters flushed repeatedly as well.

Here's the obligatory carnage pictures everybody wants to see. Will of course post more once I get the engine torn down to see how bad the crank looks

[kwikt 911]

Wow... looks nasty. I would remove the valves(simple job) and thoroughly clean. Remember to Keep all the shims in order with the valves/heads.

[Lapkritis]

Originally Posted by KTL

My fresh engine took a crapper after the engine mounted oil filter (full flow) apparently starved the crank of oil. That was a nice "upgrade" I chose to do......

Can you describe this mod and what you believe about it caused the starvation? New here... would seem filter location shouldn't cause an issue as long as installed properly.

[KTL]

Originally Posted by Lapkritis

Can you describe this mod and what you believe about it caused the starvation? New here... would seem filter location shouldn't cause an issue as long as installed properly.

What's Wrong With This Picture?

The above thread is more detail on the install of the oil filter housing. This filter housing was used on factory race cars in the old days (906, RSRs) and newer 3.6L engines like the 964 Turbo and the 993 engines.

The installation is very simple. You remove the oil cooler and replace it with the oil filter housing. Its a simple bolt-on. The catch is that on the older pre-3.6L engines like mine ('79), you need to re-establish the oil inlet. So I cut off the oil inlet tube from a junk oil cooler.

In order to have the new oil filter active at all times you must replace the engine's internal thermostat with a cap or a fancy RSR contoured t-stat bypass that directs the oil into the filter housing inlet port in a more controlled manner. JB Racing makes a nice replica of the factory part



So the installation is very simple and kinda hard to screw up. But I found a way to screw it up by using a filter that couldn't flow enough oil. I should have used a standard paper filter which has a bypass valve. The problem with my racing filter is that when the filter is compromised, the oil path is choked to the crankshaft because there is no bypass. Here is the basic oil routing diagram for the 911 engine.




You can see that the oil path goes from the pressure side of the pump to the t-stat, then to the oil cooler, then on to the crankshaft. When the t-stat is replaced with the RSR piece, oil goes directly to the oil cooler (new oil filter in this situation) with no chance of bypass. That said, even if the t-stat was in place, once it is hot/open there is no other path for the oil to take. Meaning it cannot switch back to the cold path once hot.

In my case the filter choked the flow to the crank and whatever oil that was being choked behind the filter was being dumped back into either the inlet side of the oil pump (via the pressure relief valve) or dumped back into the crankcase sump (via the safety valve) to be picked up by the scavenge side of the pump (oil pick-up)

Lastly, my oil pressure gauge is plumbed in such a way that I had no idea the oil pressure was low at the crankshaft. My oil pressure gauge is a mechanical gauge that is connected to the top of the engine case where the oil pressure warning light switch is usually found. I have an AN-4 braided oil hose that goes from this port on the engine all the way to my dashboard where the gauge sits in the location where you normally find the VDO clock. This source of reading my oil pressure is upstream of the filter restriction (the port is right next to the t-stat) and therefore it was showing good oil pressure. So it appears there is good reason why Porsche chose to put the factory oil pressure sending unit downstream of the crankshaft, in-line with the camshaft oil supply line.

Here's a picture of the filter element and the distortion caused by the restriction. The filter element flows from outside to inside.

[Walt Fricke]

Kevin

That looks like a Canton Mecca filter element.

I have a CM filter plumbed into the scavange output up front, before the oil enters the coolers up there.

I have never had a flow problem there despite using the 930 pump.

On the engine, I use a System One stainless pleated stainless mesh filter mounted a short distance away, with -12 hose connecting it to where the engine oil cooler (or your nicer piece) would be. This appears to have worked just fine as well. The 6" (quart size) is advertised at 30 GPM, which ought to be plenty. Don't recall the micron size of mine.

I have had minor issues with the CM. They point to the lack of a bypass as an advantage - debris will never get past it. Sounds good, and more or less has seemed to hold true for me, though I have a second System One filter between the oil coolers and the front sump tank just in case.

At first I plumbed the CM as CM suggests - oil enters the center, exits through the port on a side. But after an engine blow up I noticed that two layers of the filter medium (which is rolled, toilet paper style, into four or five layers) had split from the force (perhaps some incautious warmups in cold weather had done this, though). This despite the outer perforated cylindrical cage. The remaining layers, however, were intact and nothing much got through.

So I switched to pumping the pressurized oil into the outside, and it exited through the bottom in the center. This has worked fine - no split layers. But once I did find that the outer cage was dented in on one side, I suppose from the force of the oil and the extra pressure where it entered. The problem which this might have caused would be pulling the filter fabric from the glue holding it onto the end caps, thus creating a path for unfiltered oil (if laden with debris) to get through the filter. Not worse than a bypass, though.

But I am surprised that your CM (or similar) fabric filter so restricted flo as to cause prompt oil starvation - so quick it didn't show up as excessive oil temperatures.

When I change my CM filters I pull them apart. Sometimes I find a little bit of stuff in them, sometimes none.

But isn't the idiot light located at top end of the drilling which holds the pressure setting piston? And doesn't that piston get its oil, if the thermostat is replaced (or open) from the downstream side (or exit side) of the engine oil cooler? Oil follows the H direction on the diagram. Which, for your and my engines, means downstream of the extra filter in the cooler location?

The rearward location Porsche chose for the pressure sender may be safer, as it will account for pressure losses as the oil traverses the main gallery to get to it. But I don't see how the idiot light would see pre-thermostat pressures.

[TibetanT]

Kevin:

OMG! Sorry to see this.

In your first picture, is that the plugs for the sump plate and the oil tank, or is one from the pressure relief on the engine case?

Hoping for the best that the crank is not going to be needing work other than a polish and a new set of bearings.

[KTL]

Walt,

Thanks for the thorough reply, as always.

Yep its a Canton 25-184 small filter. I sort of shot myself in the foot using this filter I suppose, as I chose it based on physical dimensions instead of flow capacity. However I honestly don't know if 12GPM is insufficient. My pump is a 993/964 pump so it's got some decent pumping ability.

I did get some feedback from Canton and their belief is the filter distortion is due to the ingredients in the assembly lube (Permatex Ultra Slick super sticky red goop) and the break in oil (Brad Penn 30W break in). They believe that the filter would flow fine when warmed up. But when cold it would have a hard time passing the thick additives due to the fact that the filter element filters down to 8 microns. Seems plausible, considering the filter is quite grayish and pushed in on the outside of the media. The screen isn't dented-in on the outside, only the media is packed-in. Which in turn pushed the screen inward on the inside of the filter element.

Yes I can see how not having a bypass can be beneficial in theory. But in this case I think it proves having a bypass is wise. System 1, Racor, Oberg, Pure Power, to name a few, all implement a bypass in their high end filters. So there's some merit to having the bypass. The distorted filter really didn't strike me as impending death. I reinstalled the oil cooler because I figured it was pointless to waste another filter element, knowing that the thicker 20W50 oil would be even harder on the filtration. Little did I know the damage was seemingly already done?

My oil temperatures were "masked" by the weather IMO. When I was running this filter, the weather was crazy hot- mid to high 90's and humid. Brutal weekend back in mid July. So the fact that my fresh engine (first time back on the road/track) was running near 240 didn't surprise me, especially since I had put the filter in place of the engine oil cooler and my large Fluidyne front cooler could use some additional ducting behind it.

So for the next races (last weekend) I replaced the oil filter with the original oil cooler and also welded in a new TRE Motorsports duct in the front tub to allow better flow past the front cooler. Weather was rather cool and I was around 190 when running hard on the track. Temps spiked to 225 according to my telltale newly installed Autometer Sport CompII temp gauge (nice gauge, I love it!) which probably spiked when limping back to the pits. I could have shut it down but I still had oil pressure. I figured why not just putt putt back to my camp. Although the dull rod knock would lead others to shut 'er down instantly and let the hook bring me home to my trailer.....

I'll have to take a look at the location of the idiot light (very appropriate term in this case! ) in the oil circuit when I get the engine on the stand tonight. My belief is that the light is upstream of the filter simply because I was seeing decent oil pressure on the 0-100 psi mechanical gauge which is quite sensitive. Maybe I wasn't seeing enough.

This filter condition is the only thing I have come up with so far to reason why I had a failure. We'll see what else I find when I crack it open.

[KTL]

Originally Posted by TibetanT

In your first picture, is that the plugs for the sump plate and the oil tank, or is one from the pressure relief on the engine case?

Those are the engine sump plug (left) and oil tank plug (right). Magnets did their job for the most part. However you can see there's still a ton of crud in the sump plate. That material in the sump plate is "cold." Meaning the car has sat still in my garage for 3 days before I drained the oil to see the inevitable debris.

Thanks for the good thoughts. We'll see what the crank looks like shortly.

[boyt911sc]

Kevin,

So what's the advantage of replacing the engine cooler with the oil filter contraption? I'm not into racing or high performance engine projects, so could you educate us what was the objective of such alteration? I seem not able to grasp how a filter medium could flow freely like the old engine cooler. My'73 VW Beetle has a some what similar after market external oil cooler. Thanks.

Tony

[Walt Fricke]

Tony

Porsche did this (engine oil cooler replaced with filter) for its race motors, and I believe did it again starting with the 964s or 993s. (in any case, deleted the engine mounted cooler).

For racing I saw it as a kind of last ditch measure - if something gets by your other filter, this will catch it after the pump but before the bearings. Especially if the other filter has a bypass feature. I am pretty sure that the factory race filter (part of the whole different housing, including an externally adjustable oil pressure setting screw) did not include any bypass features. It looks like a series of stacked perforated hollow disks - not anything like an ordinary filter.

Not something a guy with an older 911 with a street motor would want to waste his time and money on. Only works with oversized front coolers, usually mounted in the valance with good air flow in and out.

Walt

[Walt Fricke]

Kevin

Have you disassembled the filter cartridge? What did you find and how deep did it penetrate?

Walt

[JeremyD]

Dude - so sorry to see this - That stinks big time (but it does sound like the cooler and duct did it's job) But seriously.

[KTL]

I disassembled the small filter and it filtered all the way down. Entire roll of toilet paper is darkened with fine particulates and only a few flecks of bearing material on the outermost surface of the filter media.

I also looked at the large filter element that was installed in the oil tank filter when the small filter had its problem. It doesn't have any large particles but it too is very darkened by...... ? Smaller bearing material? Its rather black-ish. The filter is normally a light tan color and the filter is full of fines that made it very dark. I'll post a picture of the rolled out filter media when I get home.

However, the plot thickens. As I mentioned before, after seeing the compromised small filter I decided to ditch that setup (because I didn't have a normal can filter) and reinstall the engine oil cooler. Great no problemo any more. NOT. Here's the large oil tank filter after engine failure. Granted, i'm sure the filter was compromised by the crapload of bearing material.





Well that's not the worst of it. Got down into the engine this weekend and a lot of collateral damage. Basically my assessment of the situation is a non-bypass filter is a BAD idea. Once the filter is clogged, say buh-buy to your engine in a lot of ways.

1. Cam housings heavily scored in the bores. Lots of material deposited. Had to wrench & lightly pry the cams out of the housings. These housings are likely junk now.
2. Cam bearings are scored nearly as badly. Could likely be hardwelded to repair. What a shame since these are "new" hardwelded cams.
3. A few rocker arms are pitted. Likely due to oil starvation from plugged spray bar. Also a shame since they were freshly refaced and rebushed.
4. Heads look good. Still have to disassemble but initially look OK. Hooray since these were gone thru completely and twin plugged.
5. Pistons are scuffed badly on skirts. Maybe can be lightly resurfaced and coated on the skirts. What a shame since they're brand new.
6. Cylinders are scuffed too but pass the fingernail test. Could likely be replated (again) but how many times can these be replated? One cylinder would be undergoing it's THIRD re-plate as I had that one re-plated by US Chrome on account of the old plating chipping off at the top of the cylinder.
7. Pauter rods are so-so. #3 was very stiff on the journal so likely out of round. #5 was ready to go on vacation as seen by the heat discoloration on the big end. #5 rod bearing departed the crank went all thru the engine. Other four still move smoothly but of course need checking/resizing. They’re quite old and have seen a lot of racing use. Probably time to retire them anyway.
8. Crank is not too bad considering the damage to EVERY hydrodynamic bearing in the engine. They're all wasted. Bearings were definitely sacrificed in this situation. Surprisingly a few layshaft bearings look untouched but whatever.... #5 rod journal is trashed as evidenced by the departure of the bearing. This crank is probably a mail box post now or a project for a machine shop to practice on?
9. Oil pump spins freely! How ironic is that? Will of course open it up to inspect but I suspect the inside of the Mg housing (993 pump) is thrashed

Here's some pictures of the carnage. Caution, the following is graphic and professional engine builders may find the following images extremely disturbing.

cams- note the substantial scoring on the bearing surfaces



cam housing bore deep scoring. also note the nice job I did making removable plugs for the spraybars. Cleaning them will be a piece of cake!



#5 rod journal. that's not mirror finished anymore....



#5 rod big end- note the heat coloring and the black stuff. Both of those details are a BAD thing



piston skirt OUCH



crank main bearings- FOD aplenty

[AlfonsoR]

Ouch!!!! Sorry to see all the carnage Kevin.

On the crank, probably not worth it, but I'll throw it up anyway...Nascar rod bearings?? Two Inch NASCAR Bearings

[KTL]

Thanks for the well wishes Alfonso. The 2 in. bearings are the hot setup for guaranteed quality bearings. But i'd need custom/high end rods and also the crank work. Cheaper& easier for me to just go with a good used crank and std. SC rods. I'll check with Brian Pauter next week to see what cost i'm looking at for rod inspection and a single (hopefully not more than one...) replacement rod for #5 rod that's destroyed.

[Jeff Alton]

Jeez Kevin,

If it weren't for bad luck... J/K

No good deed goes unpunished..... You were on the right track with the install of the second filter console, but got the opposite results of what was intended. What a shame. Sorry to hear of the misfortune. Hopefully you will have it up an running for the start of the 13 season!

Cheers

[fredmeister]

Your oil coolers might be packed with debris as well. So I dont want to add misfortune to your list, but you might want to consider trashing them or finding out if there is anyway of cleaning them out internally......not likely from what I have read.
Sorry man for this incident, but at least the engine died a valient death on track. Better to have loved and lost than never loved at all.....
Another annectdote on basic hydraulic theory: Pressure gages only read pressure downstream of the gage so the Porsche factory pressure sender location should tell you pressure at the number one crank journal and nose bearing.

good luck with the rebuild.

Fred

[KTL]

Nothing much to update yet. Although for future reference, readers may like to know that the cam bearings can be repaired. WebCam doesn't do it themselves but they sublet it out. $175 per is a lot better than new cams!

Yeah Jeff the kick in the family jewels is a tough one considering the intent of the oil filter install was for an additional level of protection on the engine. I figured if the 965 and 993 have it, it must be worthwhile. Especially since I can "afford" it, given that i've got a large front cooler seeing lots of airflow.

Fred,

Thanks for the heads up on the oil coolers. As much as I don't want to accept it, I agree they are also wall art/junk. Just can't risk using them again. Even ultrasonic cleaning doesn't seem like it'd get all the bearing debris out. I don't need a piece of crud dislodging itself later on down the road and making a mess all over again.

Coincidentally the oil filter project can be re-visited with the right filter install and I already have a new front cooler on the shelf, simply because my existing Fluidyne cooler up front is rather old and clogged with debris in the fins (despite best efforts at blowing it out). Felt it was time anyway to retire it. Thankfully I didn't install my new cooler before the last event or that would have been $300 down the crapper as well. The bummer is that I can't sell off the old coolers to recoup some costs. Boo hoo........

[AlfonsoR]

Man, if I lived near you I would be all over helping you put this back together...but I live in Houston...I know, I know, another kick in the jewels...Not. LOL, I'd probably slow you down.

[Lapkritis]

Thanks for the explanation... this is my nightmare. I don't mind blowing gaskets but scrubbing every bearing in an engine would just plain suck. I'd be hard pressed not to go with a full engine swap with that level of destruction. I'd say you're taking it quite well considering... must not be your first rodeo.