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YOUR RESEARCHEngine vibration
Leading reported evidence
Lubricate by engine oil is wearing out
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
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0
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1
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Read evidence and context
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Performed · outcome unconfirmed
A steel component inside the engine and lubricated by engine oil is wearing out.Check the pleats of the oil filter also.
Leading evidence: 'Lubricate by engine oil is wearing out' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check crank end play' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Replace engine mounts and the vibration is still there
Performed · outcome unconfirmed
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Performed · outcome unconfirmed · Original poster
I replaced the engine mounts and the vibration is still there.
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Performed · outcome unconfirmed · Original poster
I have replaced the flywheel and still have the same movement.
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Performed · outcome unconfirmed
Whatever, you are lucky that all you need is a new (or good used) DMF
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Suggestion · Original poster
I intend to have the crank repaired and re-hardened, install new main bearings including thrust, and replace all the bolts and gaskets that would normally need to be replaced when reassembling the engine.
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With the car in neutral and foot off the clutch I get engine vibration from 1600 - 2000 rpm. Any idea what could cause this? I would think the flywheel as I had a G35 at one time with a broken DMF and it did the same thing.
If the DMF was failing you might get misfire or CkPS codes ?Check them
It may be time for mounts anyway -so good maintenance job to do with lots of previous DIY Threads here.
I replaced the engine mounts and the vibration is still there. I am going to pull the transmission soon to do the IMS, so I can check the flywheel then.
Time to find that Shaeffler You Tube video on checking the DMF :-)
I mention this because if the DMF is 100K miles old it may be wise to replace even if it is still within spec. The LUK DMF price has come down in the the last year or so.
If the DMF is failing it has been hammering the bearings at that end of the crankshaft so check for glitter in the oil filter?
I pulled the flywheel off and it does have some play. I also noticed that the two rivets on the back of the flywheel where grinding on the case just above the crank. Any ideas why?
Wow, I would imagine that the flywheel rivets hitting the crankcase would make a bit of a racket. The pilot bearing is probably toast, and the Dual Mass Flywheel may be bad as well. Either one of these along with the rivets hitting the case could cause your "shudder"...
To be specific, the play you have is not lateral play like the Shaeffler/LUK Test Video ?
You have 'rock' & wobble as the DMF moves forward and back in an eccentric fashion ?
If so that means the source of the play is at the center of the DMF ?
Whatever, you are lucky that all you need is a new (or good used) DMF
Interestingly enough the original IMS bearing is in perfect condition at 82K miles. No play at all.
Another thing that concerns me is that there was some non ferrous shavings in the oil filter. I then pulled the oil pan and found ferrous 'dust' at the bottom. I am thinking that it maybe the thrust bearings but I am unable to 'pry' any play in the crank.
Hard to believe the RMS would be so dry with enough crank play to account for the flywheel hardware making contact with the engine block or bell housing.
Crank axial play should be on the order of just a couple of thousandths of an inch. Not that I have any numbers from Porsche just remembering the call out of crank axial play of other engines.
Radial play should be nil.
The "dust" while it looks like aluminum (can't tell from the pic and even being there one might be hard pressed to tell, although aluminum metal flake is pretty shiny) could be bearing metal.
You sure the "dust" isn't attracted to a magnet?
An oil analysis might be of some help provided you have a good uncontaminated sample to send out.
Watch the LUK video and learn why your DMF failed ?
My new LUK DMF was slightly out of balance . The Machinist drilled at the heavy spot to achieve perfect balance.
I watched the LUK videos. I see that DMF's can vary a bit in design. My DMF does not seem to have that much rotational play and very little lateral play. Would the 996 DMF have the counter flanges as well? I could understand if they were 'frozen' into position that it would cause imbalance.
Ferrous "dust" (fine particles) of ferrous material in the oil is not a good sign.
This can be from camshaft lobe/lifter interface wear or possibly a chain not tracking properly and abrading the sprocket (and itself) in the process.
I'm no expert but given what you have found I think an engine teardown is called for so a thorough inspection can be made for any signs of any issues.
Good question.
We weighed, tweaked and balanced everything ! Just like Ahsai did in his engine rebuild.The additional time and cost was......
These engines run smooth stock but when balanced it was astonishing how smooth it was.
The ferrous dust in the oil is nothing to do with the DMF.
Suggest you read any of the Threads about
FOM
,magnetic debris in oil, ferrous in oil.
Sadly there are few plausible, benign explanations.Oil analysis will confirm what you can already see. A steel component inside the engine and lubricated by engine oil is wearing out.Check the pleats of the oil filter also.
You are lucky you caught this before(?) major engine damage occurred.
The short version is -a thorough rebuild. Sorry. Don't wait until the inevitable major damage occurs.Then you will need a replacement engine.
I have the engine out of the car now and have reattached the flywheel. In this video I am lightly prying the ring gear with a flathead screwdriver. There is noticeable play in the flywheel and what appears to be in the bolts as well. Almost as if the crankshaft is cracked. However when I take the flywheel off, put one bolt back on the crank and pry with a pickle fork I get no movement.
You Tube
The DMF is bad ?
Substitute a known good, used one and retest(I have one)
Make a flat bar to attach to the flywheel bolts and retest
If your DMF has over 80K miles, just replace it.
There are many vids showing how to test a DMF
I have 82k on the dmf. I have ordered a new one since I planned on replacing it anyways. I did bolt a two foot u-bar to see if I can get the crank 'head' to pivot, but no conclusive resluts.
Your videos measure movement in 2 different planes ?
When you have bolted up your new DMF, repeat the first video.My WAG is the movement will be insignificant. Assuming it is bolted up correctly.
I have replaced the flywheel and still have the same movement. At this point I believe the crankshaft is cracked, so I am in the process of taking the engine apart. I already have the driver's side head off. My question is it necessary to pull the passenger head off to split the case?
Can you get someone to look at the crank pulley on the other side of the engine when you move it at the flywheel end to see if there's movement there, I don't think your crank will be cracked , you are either getting movement in the flywheel itself or maybe the bolts , they are stretch bolts for one use only! The other explanation is worn crank thrust bearings and maybe main crank bearings but there seems to be a fair bit of movement there!!
Sounds like your quite far along with stripping down now so you might as well carry on, the crank carrier and big end bolts are one use only too .
Let us know what you find, I'm betting thrust bearings worn by excessive play in flywheel?
The verdict is in. Bad thrust bearing.
The good and bad thrust surfaces.
Couple main bearings are pretty worn but all the journals look okay. Except the one thrust surface.
This explains why I was unable to detect and axial play in the crankshaft. The one thrust washer wore so thin that the other washer fell out of it's groove and wedged itself between the crankshaft and the carrier. This would also explain why the engine always had slow starting like the battery needed to be replaced.
It is labor intensive. I am doing the work myself. As far as cost... I intend to have the crank repaired and re-hardened, install new main bearings including thrust, and replace all the bolts and gaskets that would normally need to be replaced when reassembling the engine. I anticipate 2k to 2500.
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