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HEART ATTACK! GT3 996 OIL PRESSURE

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Old 07-17-2018 | 02:30 AM
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Default HEART ATTACK! GT3 996 OIL PRESSURE

Hi fellow GT3 lovers.
I had a gut-wrenching moment yesterday.....major oil pressure issue arose. Help please! before I jump off a cliff.

2004 model 996, 2 owners, 40k miles. I have owned for the past 11 years.
Been looked after by the same mechanic also for the past 11 years- a highly regarded Porsche specialist.
Car has always been running like a dream doing regular club level track and sprint events.

At workshop yesterday we did a simple oil change and developed an oil pressure issue immediately.
Warning light comes on when revs drop below 2500 rpm. Engine auto cuts off coming to a stop at traffic lights and sometimes when at Idle.

Workshop explained the old oil typically "thickens up" and putting in the new Mobil 1 simply highlighted the issue.
We then replaced the Mobil 1 with a thicker oil, but still the same issues.

Workshop feels the engine is simply" tired" after lots of track use. Various mechanical components have slightly worn through etc.

Definitely no issue with the pressure sender.
Not sure replacing the oil pump in isolation is a definite solution, but really no idea where else to turn to apart from a complete engine rebuild. My wife would kill me!

Really appreciate any words of wisdom, many thanks.

NB not entirely sure, but think the correct oil pump on PET is
996 107 007 94
Old 07-17-2018 | 02:59 AM
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The workshop diagnosing the engine is "tired" after an oil change when there was no problem before dropping the oil sounds questionable to me...….. I don't believe their prognosis! Something has changed from when you took the car in, to it developing the suspected oil pressure failure.
Where you present and did you observe the oil change (you say "we" a couple of times) so I assume to saw what went on.
If replacing the Mobil 1 with thicker oil did not work then their prognosis of the old oil "thickening up" is incorrect & there is something very wrong in what they did - what oil pressure are you seeing on the oil pressure gage now?
What other work was performed apart from the lube change?
I would check the oil filter for correct fitment (including the small O ring @ the bottom of the plastic spike) and then connect a mechanical oil pressure gage to double check the pressure.
Old 07-17-2018 | 06:33 AM
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Many thanks Stephen, appreciate your insights.
Yes, I was there at the workshop the whole time.
No other mechanical work was done.

Oil pressure under revs now only getting up to 1.5.
....much lower than pre the oil change.

Old 07-17-2018 | 07:24 AM
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I would check if the oil filter is some kind of an original Mann HU 719/5 x or equal quality. I've seen "compressed" fake internet filters.
And the already mentioned O-ring at the bottom should be checked
Old 07-17-2018 | 08:29 AM
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Higher weight oil is not the answer. I doubt that old gummed up oil was disguising a previous issue.

I agree with Stephan. Your first question should be, "What changed?"

• New filter
• New oil

The filter is easy to check. They are also cheap! I buy my filters exclusively at my dealer. Buy a new one and pull the one in there now. Check for any foreign objects down the well when you pull the filter. If problem persists, then it's something else.

How do you know the oil pressure sensor is not the problem?

Why aren't you changing your own oil? It's so easy to do and it helps you spot other problems when you do.
Old 07-17-2018 | 11:39 AM
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Originally Posted by JB GT3 996
Hi fellow GT3 lovers.
I had a gut-wrenching moment yesterday.....major oil pressure issue arose. Help please! before I jump off a cliff.

2004 model 996, 2 owners, 40k miles. I have owned for the past 11 years.
Been looked after by the same mechanic also for the past 11 years- a highly regarded Porsche specialist.
Car has always been running like a dream doing regular club level track and sprint events.

At workshop yesterday we did a simple oil change and developed an oil pressure issue immediately.
Warning light comes on when revs drop below 2500 rpm. Engine auto cuts off coming to a stop at traffic lights and sometimes when at Idle.

Workshop explained the old oil typically "thickens up" and putting in the new Mobil 1 simply highlighted the issue.
We then replaced the Mobil 1 with a thicker oil, but still the same issues.

Workshop feels the engine is simply" tired" after lots of track use. Various mechanical components have slightly worn through etc.

Definitely no issue with the pressure sender.
Not sure replacing the oil pump in isolation is a definite solution, but really no idea where else to turn to apart from a complete engine rebuild. My wife would kill me!

Really appreciate any words of wisdom, many thanks.

NB not entirely sure, but think the correct oil pump on PET is
996 107 007 94
Hey, what's wrong with jumping off a cliff?

I'd look here first, I'll bet they removed the oil pressure bypass fitting by mistake and did not re-install correctly
https://rennlist.com/forums/996-gt2-...e-mistake.html

any shop that diagnosed your "tired oil" as the culprit is suspect, despite your previous experiences.
perhaps they had the "new guy" do the work????
I'd recommend you DIY in the future.
Good luck and cheers

Craig
Old 07-17-2018 | 04:48 PM
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My first thought was the mechanic has done something wrong. But you say they have been working on your car for 11 years with no issue, so that's probably not it. (Although the comment about the motor being "tired" is peculiar. Not sure what that means specifically). As others have noted not much has changed in terms of parts, so I would start there and eliminate the new stuff from the list of possibilities.

Worst case you could always go with a 4 liter build!
Old 07-17-2018 | 05:33 PM
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Hook up manual dial pressure gage before proceeding forward.

once oil pressure has been confirmed by a second gage you can proceed forward!

if the ahop doesnt look at least like this take the car elsewhere asap!

Tired, what a bunch of bull! A buddy and i do all our own wrenching on 8 porsches and i just rebuilt a 398k 911 motor and most of it was still within spec! Tired yea right!
Old 07-17-2018 | 05:39 PM
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Use a mechanical oil pressure sensor/gauge in place of that electric one, just to be sure that your engine is OK. Do not drive the car before that's done.
A friend of mine got the oil pressure warning while driving, gauge showing less than 1 bar @ idle and abt 2.5 bar with revs. Engine was shut down within few kilometers (he had to get out of the Autobahn), but at least one of rod bearings is/was shot.

6GT3 mkII
Old 07-18-2018 | 03:20 AM
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What a bunch of legends you guys are!
Can't thank you enough for all of the support and the insights.

NB. I work hands-on with the mechanic so it's 50-50 re-DIY and the workshop. They helped me on a major rebuild project doing the same.

Agreed....thinking the issue maybe one of the junior staff has made some inadvertent error as suggested
thanks again!

PS had been exploring the build out to 3 .8 or 4.0 before but the bank balance just won't do it. It's on the bucket list
Old 07-18-2018 | 01:08 PM
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Please keep us informed of the outcome. I'm sure there are quite a few people interested in what you find to be the problem.
Old 07-19-2018 | 12:05 AM
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Just a further thought regards the oil pressure sender. Whether this is faulty or not?

Given the engine actually cuts off when coming to a stop, or sometimes at Idle, with the warning light coming on, this I presume must mean it is a genuine issue with the oil pressure, not a faulty sender?
or would a faulty sender automatically do this cut off of the engine?

The warning light also comes on in any gear whilst driving below 3000 RPM.
Old 07-19-2018 | 12:26 AM
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check the small oring on the filter cap
Old 07-19-2018 | 08:06 AM
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Originally Posted by JB GT3 996
Just a further thought regards the oil pressure sender. Whether this is faulty or not?

Given the engine actually cuts off when coming to a stop, or sometimes at Idle, with the warning light coming on, this I presume must mean it is a genuine issue with the oil pressure, not a faulty sender?
or would a faulty sender automatically do this cut off of the engine?

The warning light also comes on in any gear whilst driving below 3000 RPM.
Maybe. The engines control unit (ECU) is dependent on sensors to perform its job. If a sensor goes awry, the data the ECU receives is bogus, but unless their is enough redundancy in the number of sensors there is no way for the ECU to know their is a fault. The ECU acts on what it has available.

My Cayenne had a faulty ABS sensor. As a result, when idling at a stop, the speedometer would swing wildly all over the place—sometimes as high as 160 mph.
Old 07-19-2018 | 09:08 AM
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+1 on inspecting the oil filter.

On my car (996), there’s always talk of the bypass valve and spring that can fail, and it’s in the oil filter housing. Does your car have one? The spring can break on ours, causing too much bypassed and lack of pressure.

I wouldn’t drive your car at all until this is resolved.


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