8 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHStruck by lightning. Again
Leading reported evidence
Check proper operation and sealing
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
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
At the end just the valve and the seat were fixed and checked for proper operation and sealing.
Leading evidence: 'Check proper operation and sealing' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check proper operation and sealing' (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.
Clean new silicon impregnated guides installed, obviously new gaskets
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
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 · Original poster
They were completely taken apart, x-rayed, cleaned, new silicon impregnated guides installed, obviously new gaskets.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
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.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
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.
Suggestion · Original poster
The oil filter and magnetic plug both were clean; the sump wasn't off when I last saw it, although it will come off.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
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.
Suggestion
Head r&r is much more than new guides, seals, and a clean deck.
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.
8 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: 20261027T005001Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Around three years ago the IMS bearing in my 3002 C2 grenaded. I had it rebuilt as a 3.8 with the LN Engineering products, installed the IMS Solution, and I have been driving it a lot since then. Apart from the fact that I seem to get light grey smoke on cold start-ups often and consume a bit of oil, no worries. Until three weeks ago, when I noticed an uneven idle very shortly after start-up, which wound up with a "drive to garage" alarm. I made it the two miles or so with some missing, and also made it another 4 miles or so to my indy, albeit with a lot of missing. No grinding or metallic sounds. My indy quickly initally determined that cylinder 3 would not hold any compression. Using a scope, his inital diagnosis was that I might have a cracked exhaust valve. Once the heads came off, he saw that there is a "loose" exhaust valve seat. The good news is that neither the top of the piston nor the cylinder wall shows any signs of damage. The oil filter and magnetic plug both were clean; the sump wasn't off when I last saw it, although it will come off.
Both heads are at a machine shop. I assume that the valve is out of spec and that the seat is also for the trash. I am curious as to the condition of the head itself where the seat is seated. A buddy of mine tells me that there may be a new seat obtainable that is larger than the original, and that the head can be machined to receive it cleanly and securely.
Anyone have any first-hand experience? I'm hoping that I will never again have to examine the guts of this engine. And the carbon build-up!! I run only Sunoco Ultra. Wow. I thought I took a picture, but evidently I didn't.
You dodged a big one for sure. Just curious what head work, if any, was done in the previous rebuild? Loose valve seat is a known problem for M96. Jake and Len have warned us many times before.
They were completely taken apart, x-rayed, cleaned, new silicon impregnated guides installed, obviously new gaskets. I am not aware if anything else was replaced, such as the valves themselves, springs, etc.
Welcome to the club. I had a intake valve seat on cil 3 fail. It popped out and got pushed back in. When removing the damaged valve the little piece of the broken seat was still in place.
As one of the comments say ... we won the Russian roulette ... fix it and drive ...
https://rennlist.com/forums/996-foru...alve-seat.html
I see. I had my intake valve seats r&r by Len when I had my engine rebuilt. Your failure was the exhaust valve seat. I think Len also recommended r&r the exhaust valve seats as well but he said usually they see more problems on the intake valve seats.
Hey, thanks for the warm welcome. I found your thread using search. What all would up being replaced on your head? Was anything done to the affected port in the head?
The guides are one of the many wear items in these engines. You don’t know how the valves are pounding the seats with the guide wear. And then when you replace the guides you again don’t know how the valve is sealing in the seats. I think it is impossible to align the new guides to the old seats perfectly. It’s about sealing, but as important is the transfer of heat from the valve to the seat/head.
Some just lap the valve seats to get a good seal, or maybe don’t even do this. Cutting the seats aligned with the guides is the best solution. But then you need to equalize spring pressures and shim as needed. I learned from some very patient experts how important the heads are. Head r&r is much more than new guides, seals, and a clean deck. Good head work comes close to the cost of rebuilding the bottom end.
No extensive rebuild took place. At the end just the valve and the seat were fixed and checked for proper operation and sealing. The shop verified the rest of the head and apparently all looks fine. To what extent they did this I am not aware.
At the moment the engine is back in the car but I am waiting for a modification on the oil pick-up to get rid of the problem of oil starvation under hard curves.
This is a source reference. Confirm exact model applicability in the original material.
