I have had various discussions with 928 friends about how to clean up the rings lands without disassembly. Some recommend water injection to soften up any deposits, some use of fuel system cleaners like the Redline system I use occasionally [not recently]. The other approach I was considering is use of was something along the lines of Rislone or Sweepco 502.

I remember in my motorcycling days we put a shot or two of a red oil [Redex?] directly in the cylinder heads and fired it up whislt hot- smoked like a steam engine.

I like the water to steam approach as advised by Colin but have to say it scares the crap out of me. Just wondered if anyone has tried any methods that involve pouring a little "something" [any of the above?] directly into the cylinder and leaving it to soak in for a while before firing up the motor.

Just floating this to see what the latest thoughts are in the community - apologies if there is any repetition here but I am determined to try something as I am still not happy with my motor.

Regards

Fred

 

Try Kreen
http://www.kanolabs.com/engCle.html#anchor63574

 

ATF will also do the trick and create a smoke show.

 

Do you think the rings are sticking in the grooves? What does a compression test and/or leak-down test show?

Lots of stuff to put in the oil that may help. Seafoam comes to mind. I recall some have put ATF into the oil. Not sure what's on the shelves in Oman.

 

what are your symptoms?

Keep in mind the 93 GTS was notorious about burning oil, oil ingestion and the carbon deposits that go with it.....Porsche warranty replaced a bunch of engines due to this..

The really sad part about 928 evolution is it really was un-engineered as time went on.....they took away the nice early oil pan, took away the dual circlip torque tube on automatics and the better 16V oil filler-seperator...all of these caused later cars to self destruct......

 

Brian,

My motor is the one from my 90 S4. we had the motor partially stripped a few years ago when we transplanted it. A leak down test is on the immediate agenda but after a recent project to improve breathing at the filler neck with a bass *** vent to a pro vent separator and a John Kuhn designed bafffle it seems the oil consumption has not eased the way I had hoped.

I am deeply suspicious I have a ring problem and do not want to strip the motor unless it becomes absolutely unavoidable. Compression pressures are consistently 185 psi and, whereas I feel there is still something missing performance wise, I tend to think that about any motor I have ever owned.

There is a possibility I do not have the breather configured optimally, but for what it is worth it is currently configured so that there is in breathing to the rear passenger cam connection, a check valve preventing gas flow back to the inlet, the front cam cover connections are bridged [a la GTS style] and the filler neck has a 1 inch connection to the pro vent whihc [temporarily] vents to atmosphere at the bottom of the engine bay.

I also collect any expunged oil in a plastic bottle but that is minimal. I assume the baffle is doing its job. Did wonder about trying to measure crankcase pressure with this set up.

Thus would like to try something to clean the ring lands before contemplating engine strip down which in its own right is a bit risky given I do not have the facilities available to do it myself.

Regards

Fred

 

It doesn't sound like you have a ring problem.

 

Not necessarily so.

My 90GT has excessive oil consumption with great leak down numbers and proof positive it is not coming from the intake (disconnected the intake from the valve cover)

Well to be fair it could be a scratched bore where the oil bypasses the rings further down in the bore, but my guess is the oil control rings are compromised somehow. Mine doesn't show oily plugs either. And only blows blue when on the throttle when cold or quick accel while at speed. Other than that it is clean.

I will be doing my engine again properly in the near future. Until then I just live with the oil consumption.

 

I've built a new crankcase system for these exact issues.

Priliminary testing is happening now.
The GTS that we tested it on was consuming 1L every 500km.
Vehicle had 200,000 km on it.
Since the install there is absolutely no blue smoke, and in the 245 km he has driven there has now been no oil consumption.......
Once we have more miles on for testing it will be released.

 

Glen,

We have tended to assume that is the case and when the top end was off prior to installing my S4 motor into the GTS chassis, there were no signs of any problems with the bore that was checked out by the local agents chief mechanic. i did think about pulling a couple of pistons for a trial/visual check.

The previous owner of the S4 [A Dutch chap] commented how it always burnt some oil when working the motor. I believe the problem is worse now but folks following me tell there are no obvious signs of smoke other than the odd pufff on the overrun.

Hopefully the leak down test will give some indication but as Gaugeman says maybe that is not everything.

My 6 litre V12 Jag does not burn a drop of oil despite being a big V12 with a compact engine so I do not buy it is the V8 engine configuration to blame.

Regards

Fred

 

I can live with oil consumption within limits. I am going to do some careful checks to monitor the rate but it does seem to be dissappearing rapidly and no signs of any leaks. The previous owner of the S4 did talk as though he worked the motor hard and one wonders if that plus the heat [he did nothing to improve cooling as I have] may have taken its toll at metallurgy level.

Regards

Fred

 

Colin,

Keep us informed of the progress. Maybe my mods are not working as expected. I get the impression my oil consumption, despite being a 90 S4 motor, is going through oil something similar to what you describe.

Still trying to work up enough bravado to try the steam method!

Regards

Fred