geolab

there is some info that has to be clear so that the problem can be pin-pointed fast. Or maybe i did not understand.
One day the garage inspect the filters for shavings and the next day they drain the oil ? or they drained already three times now?
Not to be rude, but the person who did the oil change knows REALLY how to change the oil on a 993 ? even if he is a RL...
This question is because a lot of RL's on their first oil change, remove the pressure relief valve and empty the oil.
In one post, there is oil in crankcase and in another there is none and all the oil is in reservoir.

What I will do is
first drain the engine from the case ONLY and measure approx. the amount of oil that goes out
after no more oil goes out, drain from reservoir side.
keep both oil plugs open.
Remove both oil filters.
Watch carefully if sudden rush of oil goes out from filter seats or drain holes.
Change the oil filters both to another new pair.
Remount both drain plugs
Read in Workshop Manual section 17.00.00 engine lubrication page 123
print copy of workshop manual page 141 section 17.26.38
Remove both pressure relief valves from pump. ( These are two tiny pistons that sit in pump core seated by springs. The pistons open each at certain pressure, horizontal @ 9 bar, vertical @ 5.3, but check both. They are mounted with spring, sleeve, retainer etc. Forget one tidbit and piston opens and stays open and little or no pressure)
To remove the small piston themselves, you need a pencil thick flexible magnet.
Remove both pressure relief valves and remount exactly as in picture page 141 in W Manual.
Put 8 liters of oil in car
Remove DME and crank the engine for 1 - 2 seconds and wait a minute, repeat three or four times.
While doing that, watch your dash pressure gauge, is it going up ?
If not, go back and unplug the engine drain plug, drain the engine from the case ONLY and measure approx. the amount of oil that goes out.
same amount there was before ? more ? less?
The result will let you know if your pump is working good, or choked.
I do not think that thermostat spring affects engine pressure but little
Please bear in mind that once I have had an oil pressure sender go bad from normal to fluctuating between 1 - 2 bar, and red light, so oil pressure senders go mad but still function, they are made in CZech republic.
The only fear I have is the sound you spoke of.
The oil pump return to tank is faster than the inlet circuit to engine.
Any amount of oil less than 4 liters in the system would leave some components not lubricated temporarily and might harm permanently.
1 bar pressure would not pressure the hydraulic lifters well, so maybe the sound is this.
Imagine an internship after the service who fills the car with 3 liters and heat it up to refill at level.
You can never see the pump turning even if case was made of plexi-glass, less from return tubes.
The pump you see as a automotive part, is a housing of two pumps.
OIL is taken from tank to pump, past relief valve to pressure sender to small oil filter to crank, and later to the rest.
If it is not the Sender, thus really no pressure, the problem lies BEFORE the sender in my honest opinion.
I wish you luck

CaptainCalf

I like the way geolab thinks!

Any luck tracking down the problem yet? My guess is it's the shop's fault, but coincidences like this do occur from time to time. However, IMHO the probability is of a coincidence is much lower then the probability that the shop introduced the problem during the oil change...

Stuttgart951

Maybe I need to go back and re-read my posts but I think we are saying the same thing. I may be creating some confusion relaying information as it comes in; apologies.

Bottom line - as of right now, the engine, itself, is just fine. The "sound" was that of an engine without full pressure (lifters, etc); not any catastrophic, power plant-specific failure.

The problem is simple - oil is not circulating properly.

The likely culprits checked, thus far, show no signs of operational failure; that is the confusing bit.

Stuttgart951

The conclusion is not illogical.

I trust you'll understand if I refrain from further public comment on this specific issue for the time being...

Quadcammer

seems to be almost exactly what happened based on the op.

Stuttgart951

While I can not be 100% certain, obviously, I am pretty sure it was the valves tapping - I heard nothing which I would immediately identify as "horrifically not right."

This, mind you, was during the re-fire. Prior to shutting off the engine and pulling over (with comparatively more oil remaining on the important bits), engine sound was completely normal.



EDIT: Have I mentioned yet that, after the oil change - the reservoir tank gauge behaved differently?

Used to be that, as soon as RPM's increased, pressure gauge would pretty much peg and the reservoir gauge would drop to red - per the norm (at least in comparison to the older ones). Driving home from the shop (Saturday) the pressure gauge functioned normally, temperature was normal, but the reservoir gauge stayed at the half-way mark, regardless of RPM or load.

That speak to anything?

MarkD

yes. And that is surely no coincidence.

I would want to check the pressure relief valve assembly (previously mentioned by geolab).
If it were mistakenly removed and reassembled incorrectly or without a necessary piece, you could see that sort of behavior on the oil gauge.

The thing that puzzles me is that I would expect to see the pressure issue immediately, not X-miles down the road.
Unless there are a couple of things going on at once (unlikely). They should definitely check the pressure relief valve piston, spring etc. It is possible the spring broke AND it was assembled incorrectly after it was mistakenly removed...

You had previously said this was on the list to be inspected. Today you said the likely culprits were checked... maybe it was already checked?

The plot thickens...
Wish I had the car in front of me

Mike J

Definitely sounds like something in the oil line or bottom of the tank..the oil is not leaving the tank to get to the engine.

Still sticking with something in the line (ala rag or debris) or blocking the outlet of the tank.

Cheers,

Mike

Stuttgart951

I have been told it was already checked; and I received no update today.

I mentioned the reservoir gauge to the shop - response was something along the lines of "probably a slight over-fill."

I agree that there must be a blockage somewhere. However, I keep going back to the speed with which "rebuild" was brought up during the initial telephone call. I was also concerned that one of the higher-up's called me and not the guy who worked on the car.

Both, in concert - struck me as odd.

What's not to say that the wrong "drain plug" *was* detached, re-installed, the spring broke, got sucked up and sent down the chute towards who knows what location in the system? Maybe the pump. Opps. Rebuild time. "Eh... we hear a rattle."

Well of course you do - there's no ******* OIL in the engine!

We can speculate all day - the buck stops with the fact that the oil circulation system failed after one hour's worth of driving; following said oil circulation system having been worked on.

There is a single variable there - a screw up.

The alternative is what? An act of God? How many variables need to line up to conclude that coincidence trumps probability?

Flying Finn

I agree with those who think shop here is the culprit...

Mistake then was to take the car to the same shop, as already said, not very likely that they'll say: "we screwed up and will now fix it".

Anything can happen but my guess also is the pressure relief valve, they mistakenly took that off (instead of drain plug), then re-installed it incorrectly and maybe that's how it still is?

Go get the car, tow it to your house (or to another Porsche specialist), take out the pressure relief valve and carefully install it the way it's supposed to. DO NOT let them do any more "inspecting".

Sorry to hear about this, hopefully it's just the pressure relief valve and you get it done quick & easily!

Stuttgart951

There are channels available to remedy that sort of disagreement, should it arise.

TheOtherEric

Here's another longshot: pull your flexible oil filler tube out of the oil tank and make sure it's all in one piece. They have been known to disintegrate (mine did). I've never heard of a chunk of this material causing a problem but who knows...

matt777

I'd be down at the shop observing the whole process and asking questions.

Quadcammer

trying to prove to a jury/hearing panel/judge that their work caused the damage (unless obvious like a rag stuck in the tank) will be very difficult.

CorrdoBrit

Thats why it would be better to be there in person whilst they 'inspected'.

I guess a lot would depend on the relationship between shop and OP. He would have the bast idea how trustworthy they would be although a major cockup might encourage even the most reliable shop to cover their tracks.... hopefully this is not the case in this particular situation.

I've heard the argument too many times when a car breaks down soon after a service...oh, that's just a coincidence. Maybe it could be but chances are the resident grease monkey screwed up somewhere. Hard to prove otherwise but such an easy excuse. Sometimes I feel they do it on purpose just to drum up more business.