[bbranch]

When it rains, it pours...

After replacing the radiator, thermostat, and water pump, my overheating problems seems to be resolved (for the ~70 miles I have driven the car anyway).

However, the reason I've only been able to drive it 70 miles is that is has a vibration. I took it back to the dealer where the water pump and belts were just replaced and told them that they put the balance belts back on with the shafts out of timing because to me the vibration is *exactly* the same as when the balance belt stripped teeth a couple of years ago. However, they have re-checked it and swear all the marks are aligned correctly. They believe the problem is the DMF. I've read several threads before creating this post, but I need some more specific things to check - to either rule that out or not. I feel the vibration while driving in all gears, and over a wide RPM range (though some ranges seem more pronounced then others). Can I rule out the DMF on whether the vibration is there with clutch in or out, transmission in neutral, etc. I don't remember if the vibration came and went whether the clutch was in our out, or whether it occured in nuetral, though I think so, cause I remember it being there as soon as I started it when I went to pick up the car.



As always, any help much appreciated.



-Brett

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[flash]

ok - it is quite likely that although the marks line up, one of the balance shaft pulleys is on upside down - did they remove the pulleys? i've seen this happen myself



it is still possible that the problem is the dmf, but i would verify the balance shafts first if the problem was not there before they got in there

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[bbranch]

I don't know if they pulled the pulleys off or not. I will swear that the vibration was absolutely not there before they did the work. I did just call them back to get an estimate on cost for DMF replacement though so I could be prepared in case they are right. They did a visual inspection and are so convinced that the DMF is the right diagnosis that he said he would buy it if he was wrong. So, I guess I let them replace the DMF and if the vibration is there and they end up redoing the pulley, I get a DMF for the cost of not having my car for a week. Sounds like a good trade <img src="/forum/images/smilies/968/smile.gif" class="smilie" alt="" /> The car does have 155K miles, clutch was replaced at 111K, no flywheel on that receipt.

If it is the DMF, I don't understand why it would start showing up right when the balance belts were replaced.

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[doster]

recently i had a vibration that i thaught was a balance shaft problem

and it turned out that the alternater bolts had come loose. I couldn't imagine

it being the the dmf if it wasn't there wen you took it in, did you mean dme or the flywheel?



If they removed the pullys then flash could be right on the money <img src="/forum/images/smilies/968/rolleyes.gif" class="smilie" alt="" />

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[rustech]

The only reason they would remove the pulleys is to replace the front seals. Did they do any front end seals?



Have they done any 968 work before? My gut still tells me that it is the balance shafts that are out. Between Bob, myself, and people we've known out here with vibration issues, 4 out of 5 have been the shafts slightly off, or 180 off. Good luck.

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[Mark]

I vote for balance shaft 180 degrees off. Happened on mine. <img src="/forum/images/smilies/968/smile.gif" class="smilie" alt="" /> Replaced the DMF thinking that was it (and it did need to be replaced) but it turned out to be a shaft 180 out causing the vibration.

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[flash]

good idea to check the alternator and ac compressor for being loose - that did happen on 2 different cars here, that resulted in vibrations



as for the pulleys, generally, they are supposed to be replaced every other belt change, and many shops change them every change, so they could have taken them off and put them on wrong - did they replace your pulleys?



check the simple stuff, then move to the dmf



how did they determine that it was the dmf? there is a deflection test that can be done, but it requires removal of the clutch - ask them how they figured it out to see if they did it - a lot of shops lke to point at the dmf, even go so far as to say they will buy it if it isn't, only then to say "well, it must have been also this and that", and end up soaking you for more money - happened with a 2 shops here - these kinds of vibration seeking wild goose chases cost me 6500 bucks and ron a couple of grand



diagnostics are hard - i'm not saying the shop is criminal, or even wrong, but take the steps that you can take before getting in there on the expensive stuff

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[968gene]

While nearly everyone would be reluctant to have you plug their DME into your car, plugging your DME into another car shouldn't cause any problems. Is there a car near you that you can try your DME in? If the vibration shows up there, then its the DME and you don't have to risk buying a DME and still having the problem.

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[bbranch]

Gene (and others), its the Dual Mass Flywheel (DMF) in question, not the DME.

For what its worth, the shop is Sunset Porsche - where you lucky out-of-staters get good prices on factory parts. They have said they don't do very much work on 968s (though I have seen others there). They are supposed to have someone who knows a fair amount about 944s, but I don't know to what level.

I have an inspection appointment with them in the morning and will ask directly about whether they removed the pulleys and about the alternator and other brackets. I too, still think its the balance belts and the DMF is I'm sure not perfect at 155K miles and makes a convienient target. I'll post again tomorrow after the inspection appointment. Maybe they don't realize that the pulleys are double keyed and that even if the marks line up, it can be 180 degrees out?

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[Tom in Austin]

The balance system is sneaky ... on my car, the woodruff key on one of the pulleys somehow didn't get reinstalled and I had plenty of vibration as a result. I agree with everyone else that the most probable issue is something relating to the work that was just done.

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[bbranch]

I got to pick my car up today. Vibration is gone and car is as smooth as silk. New clutch and dual mass flywheel. Of course it is weird that it only showed after a timing/balance belt replacement, but have to trust the shop that it was the replacement of the flywheel that fixed the problem. They did show me the old one and demonstrated how you could turn the two halfs with your hands and it didn't spring back like it should.



The dearth of things that all had to get replaced at once on the car, along with other non-related financial issues have caused me to put the car up for sale. It should be well set up for another 40K miles :-) I'll put the for sale topic in the for sale forum :-)

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