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Discussion summary
YOUR RESEARCHNeed advice on suspected blown engine '99 996
Leading reported evidence
Check by renting a compression tester
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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Performed · outcome unconfirmed
Compression can be checked by renting a compression tester from any retail auto parts store.
Leading evidence: 'Check by renting a compression tester' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check by renting a compression tester' (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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Performed · outcome unconfirmed · Original poster
I just replaced the exhaust with a brand new stainless set of pipes, then drove it on a four hour trip.
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Suggestion
Did anyone bother to check the fuel pump fuse or relay?
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Suggestion
You could check the oil for coolant or debris and everything listed above you have had some great answers from very knowledgeable posters.
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Suggestion
Ignition at the spark plug can be verified with a plug removed from the well, put it back in the COP socket, and set the plug metal ground on the engine base, then crank.
[B]Ignition at the spark plug can be verified with a plug removed from the well, put it back in the COP socket, and set the plug metal ground on the engine base, then crank.
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23 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Outcome without a verified action link
The fact that it worked fine the night before and gave no indications of trouble is a good sign.
Dear Forum,
As my first post, I'd like to ask advice on my '99 996. It has the main-bearing fix completed several years ago. I just replaced the exhaust with a brand new stainless set of pipes, then drove it on a four hour trip. It ran great with added pep. The next morning, the car wouldn't start... it turned over, but wouldn't ignite. I had it towed to my porsche-certified mechanic and he could not even diagnose it!?!? He sent it the dealer to aid in diagnosis.
They say it is either a snapped timing chain, or the main shaft... and estimate at least 10 hours of labor just to diagnose it properly... then a probable engine rebuild...
Anyone have any hints or advice? Although the car is in great shape, I am thinking of selling the new exhaust or the car for parts.
Thanks in advance,
John
I assume you mean IMS instead of main shaft.
What is the dealership basing their guess on? Did they drop the oil pan and examine it?
Where do you live? You need to get it to someplace that understands the M96 engine before you make a decision. You should be able to get some recommendations on here.
You can also post pictures of what particles or pieces you find in the oil pan and filter along with a sound clip of trying to start it. You can get a lot good information from this forum that way as well.
Three things are needed for combustion. 1 proper air fuel mix. 2 compression. 3 proper timed spark.
If the engine will turn over with the key, then you can start looking into these three things. Air fuel mix can be simulated by removing air cleaner, and spritzing a little carb cleaner into the air intake while the engine turns over.
Ignition at the spark plug can be verified with a plug removed from the well, put it back in the COP socket, and set the plug metal ground on the engine base, then crank. Look for spark at the plug tip.
Compression can be checked by renting a compression tester from any retail auto parts store. screw it into one of the spark plug holes, hold the throttle down, and turn the engine over a few times. Read the gauge.
Get back to us when these three things have been checked, and report the results.
There are some fundamental questions that haven't been answered. Has the fuel pump been tested? that could cause an engine to turn over but not fire...and is certainly less severe than a blown engine.
I would never go back to the first mechanic nor the dealer. Both are either incompetent or less than honest.
Since you didn't mention any warning lights that is a good sign. The fact that your engine turned over and didn't make any strange horrible sounds when you tried to start it is a good sign. The fact that it worked fine the night before and gave no indications of trouble is a good sign. Normally when engines have a major failure they make a lot of noise and you can almost feel it in your own body.
You need a good honest mechanic who will approach the problem much in the manner suggested by docmirror.
Do not try to drive the car or "fix it" yourself. Find your local Porsche Club of America and ask someone there for a few names of respected mechanics. If they all have similar positive ratings, start with the one nearest you and have the car flat bedded to their shop. Be there when the car arrives and give a very detailed description of the events as they occurred in chronological order.
If there is doubt about the health of your engine, the shop should drain the oil, inspect the filter, drop the pan and look for debris. I'll let smarter people than me take it from there but just take deep breaths and take things slowly and don't panic.
Again, from what you described, there is no indication of catastrophic engine failure at this time, and you need a simple ABC approach to finding out what is wrong.
And if worst comes to worst and the motor, for some reason is toast, again do not panic. Come back here and you will find a variety of ways to address the issue.
[QUOTE=docmirror;13572834]Three things are needed for combustion. 1 proper air fuel mix. 2 compression. 3 proper timed spark.
If the engine will turn over with the key, then you can start looking into these three things. Air fuel mix can be simulated by removing air cleaner, and spritzing a little carb cleaner into the air intake while the engine turns over.
[B]Ignition at the spark plug can be verified with a plug removed from the well, put it back in the COP socket, and set the plug metal ground on the engine base, then crank. Look for spark at the plug tip.
Defintely don't recommend this due to the high intensity spark from the coils.
It should be easy to tell which plugs are firing properly & which are not.
1st step is always inspect oil filter, quick,easy & little if any cost.
John - thought we would get through an entire week without a "help my engine is blown" thread. Now that being said, think about this....if a timing chain snapped or the "main shaft" broke, first the engine cranking would make terrible horrible noise and probably would not crank to begin with. If it does crank, and doesn't sound like a bucket of marbles, but just won't ignite then it is one of two things, no fuel or no spark. I take it no CEL's because that would be easy. Did anyone bother to check the fuel pump fuse or relay? Running fine the night before and then cranking but not starting...I would not panic just yet, could be something simple and easy. Hopefully the Porsche dealer will give you some practical good news today. Good luck!
Remembered one more thing that creates this no start problem - the crankshaft position sensor CPS. When everything else has been checked, fuel, spark, many times over it has been the CPS. Maybe the Porsche dealer can just replace it and you will be on your way.
Hi JBradley welcome to the group. How long have you had your car and has it been serviced by you or a garage. The term a blown engine would indicate catastrophic failure and this tends to be a noisy painful death and not a quiet over night occurrence. You could check the oil for coolant or debris and everything listed above you have had some great answers from very knowledgeable posters.
Hope you can update us once its been correctly checked. O_Sr
Then don't do it if you don't know what you are doing.
Oh? Easy to tell which plugs are firing? When the engine cranks but doesn't fire AT ALL? Do tell, I can't wait to hear how you are going to tell if this is ignition related without removing a plug. Should be interesting.
Inspect the oil filter? Let's review: OP says the engine turns over(cranks), but will not start running. What are you going to learn about failing combustion from the oil filter?
Maybe in the future, if you have advice you leave me out of it, and put your own words of wisdom up here sans quoting(and failing to quote properly at that). Or, if you don't like my advice put me on ignore so you don't have to see it.
Wishing the OP best of luck with better diagnosis... From the description it doesn't sound like a "blown engine" to me.
First, check for spark & fuel delivery, and timing. You shouldn't have to tell a competent shop these things!
Then check the oil and filter for debris.
g'luck (again)
I think there is a member out there creating a new account and starting a new thread like this weekly. I see more 1 posters in the 996 forum than any of the other forums I frequent.
John Ireland - I think you read the OP's emotions right on this! I'm sure you will pushed around on here for the tech suggestions - But personally I think you got the bigger picture and said the right things! Right on man!
People often can't comprehend until they are set in the right mind set!
Good peanut butter vibes needed by all that are in need of knowledge!
No, It's Better To Just Pop In And Opine With No Idea What's Going On.
I'm sure JD has the solution/explanation and will enlighten OP and the rest of us.
Not from an IMS(B) perspective they don't, I've personally killed enough engines to know all types (although I have yet to destroy a V8) can fail catastrophically.
This is a source reference. Confirm exact model applicability in the original material.
