16vsilverstreak

Just did this on an '88 S4. Before engine felt tight when turning, after tension relieved the engine turned smooth and easily.

Mrmerlin

and when you check the front flex plate also include to check the rear pinch bolt,
if this hasnt been done,
you will probably find the rear pinch bolt is loose.
NOTE on the pinch bolts add a drop of blue loctite and torque to 66 ft/lb

MainePorsche

silverstreak, go to liftbars.com and get a Pklamp. Easy to install. They work. Ken also has some other things there which are great for your 928.

FredR

If you have experienced a potential problem scenario you would do well to clock the crankshaft end play to reassure yourself nothing has been ground out of the thrust bearing/thrust face. To experience what you describe probably had potential to destroy something- hopefully you caught it in time.

Every 928 automatic owner should do this check to establish a benchmark for comparison should something untoward happen.

Alternatively, just cross your fingers and hope for the best.

Regards

Fred

Black Sea RD

If this is true then you already have some engine damage.

Check the oil, oil filter and plug next oil change to see how much metal sludge there is.

Also do as Fred suggested and get a baseline crank shaft end play measurement done.

Depending on the results, it might be prudent to not spend anymore money on this 928.

Tails

+! to Fred's and Constantine comments.

To know exactly what is "going on" do a bump clearance on crankshaft thrust bearing using a dial indicator to determine whether the thrust bearing clearance is within Porsche's specifications and in addition, if the bearing is within specifications, but worn I would also get a Lub Oil analysis done to specifically obtain the metal type and content contained within the oil. If the thrust bearing has worn towards the maximum limit then I would give serious consideration to its replacement together with a through inspection of the crankshaft thrust faces to determine whether they should be minimally ground.

I also agree with Stan's comment to check the aft flexplate clamp's allen headed set screw, that it is tight.

If all is good I would also suggest that the front and rear clamp set screws are renewed and tightened up to 10% above the WSM's specifications.

Until the above is done I would not run the engine.

There are a few ways to stop the forward flex plate migration and loading up of the crankshaft thrust bearing and my preferences are as follows.

1. Constantine's super clamp (scheduled to fit one to a 1990 S4 Auto (BEST)).
2. PKLAMP (2nd Best).
3. Locktite (3rd Best).

The cost is also in the order above.

ROG100

Just listen to what these guys say and check the end float on your crank - very critical.

16vsilverstreak

Checked oil filter, no trash, it looked good. Copy on the end play.

Andy Kay

So glad to have Sean nearby. The Pklamp was one of the first things he did!

FredR

The "highest cost" is in the order above! Unless of course Constantine and Ken have reduced their prices to less than $6! [How I wish]

The OP's symptoms do sound somewhat ominous however what is done is done and best to be cautious until checks indicate cause for tears or Hari Kari.

When I purchased my current GTS the previous owner thrught the engine was OK as it was running. Took me about 5 minutes on a ramp to condemn the motor. I was tempted to gouge him but settled for a good deal instead given I knew the vehicle history, the relatively immaculate condition it was in and the fact that I had my '90 S4 motor with damaged externals.

When we stripped the GTS motor the crank/thrust bearing was a dog's breakfast. The thrust/main bearing journal had spun, the webs were cracked.. you get the picture- and yet the motor was still happy to spin- felt sick as a parott though. Let's hope this has not happened in this case [yet!] fingers crossed.

Regards

Fred

Tails

Checking the Lub Oil filter will only alert you to what you can see, not the micro metal particles that may be pumped through the engine oil ways.

Bonton

Will someone please explain this procedure -physically- I am ready to buy a dial indicator but don't know where to place it/where to measure etc. Roger has also mentioned to me over the phone to get a dial indicator and another magnetic component to place forward(?) of the crank. So does this mean to get a magnetic dial indicator?

Each time this is mentioned it seems it is even more critical than simply relieving the pressure on the flex plate but I can't seem to get a clear read on how to do this.

Thanks, Josh

FredR

Josh,

A dial indicator is a simple enough device- it is not magnetic in operation- just in the mounting method sense- the holder however can be magnetic- you simply use the magnetic base to hold it in place providing you have something ferritic to hang it from [i.e. steel providing it is not austentic stainless]. Similarly such holders can also be mechanically bolted to something.

The dial gauge has a plunger, you mount this such that the plunger is axially aligned with the crankshaft and then zero it on a surface that moves axially with the crank such as the flywheel face, ring gear whatever you can sight it on. You ensure that the gauge is slightly depressed and zero that point. You then get some kind of pry bar [a big screw driver works] and pry the flywheel in both directions- full forward, full reverse and note the dial gauge travel over both extremes. A normal 928 crank usually floats in the 0.18 to 0.2mm range, the factory spec limit is 0.4mm. If you measure something close to the limit you would be well advised to find out why. Anything over the factory limit and you are probably in trouble and if close to 1mm the motor is probably toast as the crankwebs will probably be in contact with the crankcase which becomes the de-facto thrust bearing. For this to happen the thrust bearing will have been ground out and the thrust face of the crank more than likely demolished. However for such extremes to occur there is a good chance the thrust bearing would have seized if the molten white metal cooled and welded itself to the crank.

However, on the positive side no one should even think about such possibilities until such time as you know where your crank end float sits- something all 928 owners- auto or manual should have a benchmark measurement of.

Regards

Fred

soltino

Does any part of this thread apply to an 82?


tino\

Mrmerlin

^^^well yes you would want to check the flex plate,

and recheck the torque of the pinch bolts,

all 928s seem to have loose rear drive shaft pinch bolts,
a drop of blue loctite on the bolt and torque to 66 ft/lbs