Hello, m

I'm having a problem with my 997.2 GT3.
The oil gauge is fluctuating at idle between 1-3 & lately I noticed a ticking sound coming from underneath the engine driver side.
The ticking sound only at idle, when the car is warmed up & once I tap the accelerator the sound goes & then back to idle the sound comes back.

 

Varying/low oil pressure accompanied by any engine noises or other untoward engine behavior (like varying idle speed) must be assumed serious until determined otherwise.

Now the fluctuating oil pressure gage may by itself may not be that big a deal. My 2003 Turbo oil gage jumps/jerks about at various times. However, at no time does it ever fall below its current reading. It falls when it first jumps up then comes right back down to where it was. And the engine gives no indication the oil pressure variation is real. I think it is therefore an artifact of the gage and probably its electrical connection.

But with the ticking noise...

Sure, a number of things can explain the ticking noise -- I won't list them here -- and not all signal doom and gloom.

But as I started with you must assume the symptoms/behavior serious until it is determined otherwise.

Thus my recommendation is to get the car flat bedded to a qualified shop. There I suspect one of the first things done -- besides confirming the oil level is correct -- is to connect a real pressure gage to the oil system and determine if the oil pressure fluctuating is real or an artifact of the gage.

Based on what the tech finds this determines what is done next.

 

Thanks for your reply..
I took the car to porsche service. They preform the oil pressure test & the result was at idle less than 1.2bar which is the normal reading & was (1bar) with the sound appearing.
As well as the diagnostic was showing a camshaft variable position error..

 

Thanks for your reply..
I took the car to porsche service. They preform the oil pressure test & the result was at idle less than 1.2bar which is the normal reading & was (1bar) with the sound appearing.
As well as the diagnostic was showing a camshaft variable position error..

 

Perhaps the oil pressure is low because of a failure of some kind with the camshaft position device? This has failed in such a way that when activated, when it should be activated, it leaks and represents a large internal oil leak? Hence the low pressure and noise?

What does the Porsche service department propose to do about the camshaft variable position error and noise?

 

Today I'm getting a full report & hopefully they find the problem.

 

Compression test is done see result in the pic?

 

Compression test can produce questionable results.

If the engine is hot when the testing is started as the engine cools this can affect compression readings.

If the engine is cold the first few cylinders tested can have lower compression readings than cylinders tested later, as the cranking will have oil squirted on the latter cylinders tested which can improve their numbers.

(Back in the day when cylinders were suspected of being worn out oil was squirted into the plug hole and a compression test or leak test re-done. If the numbers improved this suggested the problem lay with the rings/piston/cylinder fit/clearance/condition. The oil helped the rings to seal better under the test conditions.)

If one or more lifters not functioning properly this can affect cylinder filling and the compression readings.

If the cam timing adjustment is faulty this too can affect cylinder filling and the compression readings.

A leak down test is sometimes done to try to pinpoint the cause of the variation in compression.

A cylinder is pressurized and a careful listen is made at the oil filler tube for any signs of escaping air. If detected this suggests air is making it past the rings/cylinder walls.

A careful listen is done at the intake -- the throttle body can be removed. If sounds of escaping air detected here this suggests air is leaking past intake valves.

And last but not least a listen is made the exhaust outlet -- or the exhaust manifolds are unbolted from the engine so the tech can listen right at the exhaust port -- and if any sounds of escaping air detected at the exhaust outlet or port then one or more exhaust valves in the cylinder under pressure is leaking.

The leak down test doesn't rely upon how effectively the valves work as the engine spins only that the valves are closed, or assumed closed, when the piston is positioned at the top of its power stroke or some distance down the power stroke -- but not too far down that the exhaust valves begin to open.

Assuming the test results are truly representative of the cylinder compression the numbers are not good, in my opinion.

9.6 bar is 139.2psi. 7.2 bar is 104.4psi. The difference is 34.8psi.

Generally the readings want to be within 15% or maybe 10% though I do not have access to Porsche specifications and maybe Porsche calls for less -- or unlikely but allows for more -- variation between cylinders?

This if the best cylinder is at 139.2psi the lowest reading cylinder should be no lower than 118.3psi.

Obviously, at 7.2 bar or 104.4psi cylinder #1 is lower than 118.3psi.

I am not qualified to advise you to ignore the shop's test results. And the test results may, probably do, reflect reality.

What does the shop have to say about the results?

What does the shop recommend as the next step?

If you have confidence/trust in the shop then place the car/engine in its hands and move forward.

 

A compression test is not something that would be done to understand either low Oil pressure or a ticking noise.

Lets start with the fluctuating/low Oil pressure. As suggested already, get an external meter on the engine to establish if its actually low and if its a sender unit of the gauge. If the pressure is Ok, the ticking noise could be associated.

It could be a Cam follower not pumping up and what you are hearing is excessive hydraulic lash. I don't think so. I would have the shop remove the upper covers form the Camshaft actuators and check to see if the bolts have back out. Common fault. It may be one of those instances where you can hear the noise with a lower engine noise at idle and not when the RPM's are higher, but the noise is there all the time.

The 1st test is to fit a good calibrated Oil pressure gauge to the engine and run the engine up through the RPM's and establish the oil press is stable and correct. Then work from there. The compression check told you nothing for this fault.

 

That is pretty darn good advice. The initial complaint was fluctuating oil pressure with ticking.

Repeating what has already been said: The fluctuating oil pressure can be a possible gage/sensor problem or it can be a real oil pressure problem.

In the first case the ticking can be something unrelated and in the 2nd case the ticking can be from real fluctuating low oil pressure or it can be unrelated.

So, to receive a fluctuating oil pressure compliant and whip out a compression test to me seems to be a rather odd path to take, but I didn't want to get into a situation where I was trying to overrule a professional tech, manage the diagnosis of the problem, from afar.

With more time to reflect on the compression test results, I have this to offer (for the sake of the OP who I assume will read this): With no misfires being logged this strongly suggests the engine is reasonably healthy and this would require the compression to be reasonably good too, notwithstanding the compression test numbers.

So, your recommendation to perform the "1st test" and work from the results is well, pretty darn good advice.