M96 Engine Failure Mode List

[thstone]

With all of the talk about the IMSB and engine failures, I went looking for the often rumored list of 25 (or 26, or 27, or...) M96 engine failure modes but couldn't find it.

Does anyone have this list? If not, here is my first cut at creating it. Feel free to add to this so we have a complete list.

I can proudly stand up and say, "My name is Tom and I have personally experienced engine failure modes #12, #13, and #5."

What is your engine failure mode number?

M96 Engine Failure Modes

1. Cylinder D-chunk
2. Cracked cylinder
3. Loose cylinder sleeve
4. Porous engine case
5. Spun rod bearing
6. Rod bolt failure
7. Rod failure
8. IMS bearing failure
9. IMS gears not fixed to intermediate shaft (press fit failure)
10. Timing chain failure
11. Timing chain tensioner (paddle) failure
12. Valve lifter failure
13. Valve lifter carrier failure
14. Crankshaft failure
15. Cracked head
16. Head gasket failure
17. Oil starvation (high g cornering)
18. Variocam servo failure
19. Blocked oil pickup (excess engine sealant, aka spaghetti)
20. Oil pump drive shaft failure (hex shaft)
21. AOS failure resulting in oil hydraulic lock in cylinders

[Chuck W.]

None, zero and nada.

[jaykay]

I can proudly stand up and say, "My name is Tom and I have personally experienced engine failure modes #12, #13, and #5."

What is your engine failure mode number?

Tom....it sounds like they even have an m96 therapy group out there

[Swhitcomb]

Mine jumped timing and bent valves on cylinder number two.

[jsceash]

I have a 12 year old car that the engine is Rebuilt sitting in my garage. It would have had an IMS failure if let alone. With that said purchased in 2010 with 27,000 miles it had 1 service at 15,000 mile 5 years before and 1 by the owner to sell the car. The bearing and IMS tube was oil filled and rattled when removed but had not started to flex.

I bought a 3.2 motor with 41,000 miles, records show it had 2 services performed with a #1 found or starting when it was tore down to rebuild because it was a flood salvage bought as an upgrade. Possibly turned over with water in a cylinder but I'm not certain. I rebuilt it anyway.

I'm not certain what your expectations are, but if your running a 15 year old car that had + 80,000 miles on when you bought it you made a bad decision, if you thought it was going to be dependable. If you're running a garage queen that has 50,000 or less miles, in 15 years and a total of 3 oil changes one every 4 years I have nothing to say but read what happens in stagnant oils with moisture in them. If you're driving a 15 year old car that the engine failed after 120,000 mile and the body was still intact, guess what your above the curve for almost every car manufactured.

[steved0x]

#22, loss of oil pressure/shear value due to overheating causing all of the items above? Or is that a possible too cause of severs issues above.

[Jake Raby]

This should be split into catastrophic and non- catastrophic.

That said, nothing good will come from this thread.

[thstone]

Originally Posted by jaykay

Tom....it sounds like they even have an m96 therapy group out there

Yes, it has been suggested that I might need therapy!

[BRAN]

...where is the wood....knock knock knock...and my number is 0.o

[Jake Raby]

Every instance has a primary failure mode. From there, the secondary, tertiary and other failures will stem.

Often times the primary failure is either misdiagnosed, or is confused with secondary failures.

A good example is a failed scavenge pump that appears to be a primary failure, BUT the reality really is a timing chain that failed and a piece of it's roller found its way into the oil. The scavenge pump picked that up, and caused the pump to seize. From there, the exhaust cam drive sprocket (which drives the scavenge pump) will slip and retard valve timing events greatly, kissing valves into the pistons.

Thats just one example. I could go on with those instances for days.

[thstone]

Jake, I have no time nor intention to engage with you. For whatever reason you don't like this thread. I am more than happy to let it die. Let's all move on to something else.

[Timco]

No failure number for water pump failure resulting coolant loss or no coolant flow, or RMS resulting in no oil?

I think Jake only makes a valid point that often the "cause of death" listed on the death cert is often not the actual issue that set off the chain of events.

[Jake Raby]

Never mind me... People just don't want to hear anything more about failures, even if they need to.

[njbray]

Heard enough of failures - how about "what hasn't failed?" on my Boxster!
I've never had a wheel fly off (beetle), never had the roof/top peel off at 70 (MG),
never had the hood fly open at 90 (MG), never had the muffler fall off at traffic lights (beetle), never had the throttle stuck wide open at traffic lights (beetle), never had gear knob come off in my hands (spitfire), never had my hydrolic suspension collapse and brakes fail (Citroen), never had a spark plug shoot out (Honda 500), never had my radio vanish into the dash (beetle), never had brakes fail and land on roof of hair salon (fiat 128 - after I sold it!), never had the headlights fail going down country road at night (honda 175), never had rust fall off bottom of doors when closing them (Lancia Beta HPE), never had the brakes fail on one side (Renault 21), I could go on......
Happy Easter

[Gelbster]

Interesting subject.
I am grateful to Thstone for staring this thread. It is a good suggestion to distinguish between the fundamental cause and mere collateral damage as Jake explained.
So why not try a "Fundamental Failures" thread?
IMSB
Water Pump
....

[Giller]

It's all well and good to share - misery does love company - but I for one hope to never experience anything off this list.

Remember people - there are a TON of Boxsters on the road that still have a lot of original parts on them with lots of KMs and are still going strong. Many still even have their original IMS.

I still bet that it's a minority of owners that experience something on this list.

[Jamesp]

The second most interesting part of this thread is the reaction to it. The most interesting part is the data presented on failures. As an engineer I have zero (0.000) capacity to feel any emotion about this topic as I view it as purely technical data and am thankful for the information. Some folks clearly have an emotional investment in this data which frankly completely baffles me. Guess that's why I'm no fun at parties.

[mikefocke]

Rust out in 2 years (Nissan), transmission fail (Honda), transmission bolts fall out and seen out the rear view mirror bouncing behind the car (Chrysler), 5 brake cylinders fail in first 25k (Honda), head gasket fail costing engine (Alfa), window crank fail 20 times on a new car in first 24 months (VW/Porsche), discover 8 years later dealer had sold a car involved in an accident (Chevy) ....

Drivers with no trouble probably never find the forums.

[flaps10]

If you're driving a 15 year old car that the engine failed after 120,000 mile and the body was still intact, guess what your above the curve for almost every car manufactured.

Do you have data to support that? You must be used to driving a Chrysler or GM product. The list of cars I have purchased starting with more than 120k miles is way, way longer than the list of cars I've bought with low miles. I have not had to remove a cylinder head on a car in 25 years, nor have I had catastrophic failure until now.

What cracks me up more than a continuous flow of IMS threads are the number of people who wish to have such threads deleted. Let's not talk about ass cancer, so no one will get it. It is as if jamming your head in the sand and refusing to talk about it will make the "myth" go away, or that it will keep the value of your awesome sports car from tanking any more than it already has. If that is the case, then buckle up because these cars now cost more to fix than they are worth (just look at the number of rollers for sale). But take heart because according to the past two issues of Exellence after 30 years of looking up the nostrils of 911 drivers, the 914 is now officially an awesome car and a true Porsche! So there is hope.

Here:

This is the MINIMUM pile of parts you could expect to get away with and reassemble an M96 when an IMS bearing lets go. And I don't mean coming apart and destroying valve timing. My engine ran perfectly and I caught metal in the filter on an oil change. Not even very much metal. My car is a double row IMS, the kind that supposedly don't fail often.

Thanks to a single direct comment from Jake I abandoned plans to replace my IMS and flush the engine. I'm SO glad I followed his advice (never spoken to the man or paid him a dime). I put the past several months of my spare time into getting my car back together with the minimum of damage to my wallet. Honestly I should have spent about $6k more than I did. All I'm getting for my efforts is the 120k mile car I bought, and not a new engine.

When I took my engine apart I found evidence of a previously welded cylinder head (#15), a busted oil ring (not on the list), a spun rod bearing on cylinder six (#5), and of course the IMS (#8). So either my engine is a complete s*** show or these engines have some "flaws". Some of both I suspect.

[Jake Raby]

Thanks to a single direct comment from Jake I abandoned plans to replace my IMS and flush the engine. I'm SO glad I followed his advice (never spoken to the man or paid him a dime).

That made my week, and its only Monday. Glad what I shared was helpful.

I see your pile, here's my pile after 6 months. Weighed in at 6,500 pounds at the scrapyard last week.