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THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
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YOUR RESEARCHIMS Bearing Failure in 996 Turbo Engine
Leading reported evidence
Use intermediate shafts in many engines, even air-cooled variants
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Performed · outcome unconfirmed
Porsche has long used intermediate shafts in many engines, even air-cooled variants.
Leading evidence: 'Use intermediate shafts in many engines, even air-cooled variants' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Replace ims completely, since it killed the sprockets too' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Replace ims completely, since it killed the sprockets too
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Suggestion
I have one here now that had a ton of wear on the thrust deck, and I had to replace the IMS completely, since it killed the sprockets too.
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Suggestion
"While the engine still uses an intermediate shaft to drive the camshafts, the oil pumps are driven directly by the crank.
Use plain bearing supported ims, like my ims solution
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Suggestion
But, of course the Turbo Mezger based engine uses a plain bearing supported IMS, like my IMS Solution, so even if these thrust decks wear heavily all that happens is the engine makes noise at low speed.
Use plain bearing supported ims, like my ims solution
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Suggestion
But, of course the Turbo Mezger based engine uses a plain bearing supported IMS, like my IMS Solution, so even if these thrust decks wear heavily all that happens is the engine makes noise at low speed.
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19 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Someone recently told me that the IMS bearing issue did not exist in the 996 Turbo and that surprised me. I thought that the 996 Turbo had the same 3.6L engine as the normally aspirated 996. Can anyone confirm if the IMS bearing failure is a non-issue in the Turbo?
NA 996 has the M96 engine with the problematic IMS bearing. Turbo 996 has the Mezger engine which does have an IMS bearing but completely different design and configuration than M96 and not prone to failure.
^This^... and, from Total 911... "While the engine still uses an intermediate shaft to drive the camshafts, the oil pumps are driven directly by the crank. What�s more, the GT1-derived block has a different oil gallery design that ensures the IMS bearing remains lubricated at all times."
I edited my post previous your post. It should have read no IMS issues. Im pretty sure that all H4/6 type motors have to have some kind of IMS to spin the over head cam shafts.
Understood - it's one of those things where people have this built in heuristic of Mezger or air-cooled = no IMS, bulletproof when it's not exactly the case. An m96 can be updated to the reliable IMS design as we know. Beyond that, I'm not at all convinced a turbo is a cheaper car to run in any reasonable timeline. More money going in, more complexity & different bugs to be dealt with aren't exactly the panacea that some make ownership out to be.
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Well of course, a turbo costs more to buy initially, is more powerful which means it eats more gas, gets going a lot faster so you get tickets easier or crash easier, so yes, it's more expensive in some controllable ways. But the big difference: the turbo doesn't have the 20 or so (how many are there?) catastrophic modes of failure that on a whim, can and very likely completely destroy the engine rendering the car a roller. That, as we all should know around here, is the big difference.
Porsche has long used intermediate shafts in many engines, even air-cooled variants.
One of the big reasons why the IMSB fails in some 996/997s is because Porsche wanted to use a lower-cost cylinder head design and have just 1 cylinder head casting for the engine instead of two (unique) heads.
Porsche did the same type of mistake when they went to a single head gasket design in later M96 engines and had to standardize coolant holes. This cost savings measure is thought to contribute to bore scoring issues.
So there you go - the balance between cost/performance/reliability on the two items became...unbalanced.
Oh, and most importantly, don't let anyone convince you that by simply adding a turbo to a NA M96 engine it will make it bullet proof. The IMS can still fail. Why? Because if you shoot the engine with a powerful rifle, it will die and when it does, most people will blame it on the IMS.
The only IMS issue the M96.70 Turbo engine has is wearing the thrust surfaces of the layshaft. I have one here now that had a ton of wear on the thrust deck, and I had to replace the IMS completely, since it killed the sprockets too.
But, of course the Turbo Mezger based engine uses a plain bearing supported IMS, like my IMS Solution, so even if these thrust decks wear heavily all that happens is the engine makes noise at low speed.
