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THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCH996 M96.70 engine failure
Leading reported evidence
Replace oil
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
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Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Performed · outcome unconfirmed
I changed the oil after six months and noticed debris in the filter.
Leading evidence: 'Replace oil' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Clean on the outside' (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.
Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.
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1
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Performed · outcome unconfirmed
I then ran the car for another 600 km and took off the filter and again debris ( brown plastic/Bakelite and som black residue) som small pieces of metal , very few .
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Suggestion
It's just extremely clean on the outside, but all of what matters is on the inside.
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Suggestion
This is the 5th engine in a row I have assembled in the clean room without a break..
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Suggestion
The engine is still running like a dream, smooth and quiet.
Discussions that performed work without a confirmed outcome
1
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Performed · outcome unconfirmed
I then ran the car for another 600 km and took off the filter and again debris ( brown plastic/Bakelite and som black residue) som small pieces of metal , very few .
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
17 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
0 acknowledgements have no verified action link; they do not establish a repair result.
Generation: 20261027T042512Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Hi
New to the forum so wanted to share a recent experience. I understood the M90.76 tt 996 engine was very robust but this one let go at 57K Miles.
Symptoms
Rumbling noises coming from below power steering pump. Initially thought the PS pump was getting noisy. The car was driven very gently to get it home but within 2 miles it stopped, just as if the ignition had been switched off and it just coasted to a halt. No rattles bangs or anything to suggest a major failure. Attempting to restart and the engine was locked solid.
I removed the engine and started to explore, and it turned out the bank 2 cam chain guide rail had broken up and parts of it had jammed in the timing gears causing the cam timing to jump. I assume the ecu shut the engine down due to a large differential between the two inlet cam positions. Once the main chunks of plastic had been cleared the engine could be turned fully. Even though the cam timing was well out there appears to be no collisions between pistons and valves so there is a good interference tolerance in this engine. I will know more when the heads are removed.
I hoped a new guide rail would solve the problem but looking at the oil filter it shows a mass of plastic swarf has gone through the oil system and there are some bronze fragments among it suggesting a bearing failure, so the whole motor will now have to be stripped. I suspect the oil strainer pickup will be clogged and the oil pressure relief valve will be full of debris so the cases will need to be split to get to these.
A few pictures of the damaged parts
996 M90.76 cam chain guide failure
Is this a common failure ?? I cant find any other references to this or any other major failures on the M90.76
Happy to post more as the rebuild progresses.
TBB
Yes, TT engines also break... Just so the non- believers can see.
This is a common failure for the TT engine and we see it here from time to time. This is often NOT the primary failure, it's collateral damage. The primary failure is generally timing chain failure that chews into this guide as the chain becomes compromised, but holds together, rather than snapping in half.
The good news is, that it's repairable in most instances.
I had a cam pad break and jam the chain gear too but my filter was clean. It broke because it wore through due do to mileage (200K). Just as Jake wrote, yours was sawed away pretty quicly and the debris got caught in the filter.
You are very lucky that the chain didn't snap!
As it is now you must approach with great care; because when this happens it retards cam timing, and often this means the exhaust valves will contact the pistons on the affected bank of cylinders.
This can happen with just the chain rail failure, with the chain staying intact. Also, I'd expect some of that debris to have made it past the filter.
Repairable, but definitely not for the faint of heart...
Hi
I seem to be having a similar situation.
I bought the car two years ago ( 2002 996 turbo). I changed the oil after six months and noticed debris in the filter. I then ran the car for another 600 km and took off the filter and again debris ( brown plastic/Bakelite and som black residue) som small pieces of metal , very few .
The engine is still running like a dream, smooth and quiet. What did you dod about yours? Was it repairable? I�m considering an exchange engine as it has done 180 000km and has a minor oil leak.
Any one got any advice as to what is best? I haven�t dropped the engine yet
Martyn
A local customer of mine has an M96.70 complete engine with 18K miles total for sale. It has nothing wrong with it. He plans to sell it cheap, I can connect you with him.
Be VERY careful with purchasing an exchange engine, I am building M96.70 right now, as a result of a butcher who "rebuilt" it. No corners can be cut with these engines. None.
It's kind of dirty now.. This is the 5th engine in a row I have assembled in the clean room without a break.. After this one is done I need to scrub it all down really well. Took these pics late last night as I finished bank 2 cylinder and pistons.
More work has gone into the mechanicals than the cosmetics.. It's just extremely clean on the outside, but all of what matters is on the inside.
I've got about 100 hours into it at this point.
Ok Thanks I will be interested if its a good engine. i�m in Sweden but its not so easy to find anything over here.
Do you think my original engine will be salvageable as well? The oil leak I talked about is also an issue and it is at the back of the engine.
Get him to contact me if you can. Is it a complete engine or with the ancillaries stripped?
thanks
Martyn
The engine is 100% complete. Even has the turbos and wire harness. It came out of a car that had a front side impact and it wasn't damaged. I can help him ship it to you if you want it. We ship to EU routinely.
BTW- I am sure the old engine is "salvageable" but repairs for these engines start at 20K, builds start at 30K ( I won't touch one for less than 40).
I am sure you can buy the whole engine I'm talking about for less than 15K. You could sell whats left of your old one for 7-8K very easily.
