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Vibration under aceleration

Hi all,

Im looking at a 1979 euro 930 and had a report done on it. Part of the report says that there is a vibration when revving the engine and under load. I know that not a lot to go on but does anyone have any idea what that might be? The description sounds bad to me but the seller is maintaining he has never noticed it.

I havent driven the car yet as its 1000 miles from me but trying to work out if its worth flying out to see it or not.

Cheers

Old 05-26-2014, 10:05 PM
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Vibration under load like your describing is probably one cylinder putting out less power than the rest. Do a compression and leak down test.
Compression check is quicker and easier and doesn't require an air compressor and leak down tester.
Old 05-26-2014, 10:16 PM
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Good advice. Another issue could be a mount problem - in the trans/engine area. Damaged rubber mount, or loose bolt etc.
Pretty hard to diagnose with the info. But if you check both the above, should uncover something.
Where is the car - I am guessing you are in NZ.
Alan
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Old 05-27-2014, 12:46 AM
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How did they do the test? I think we need more detail
Old 05-27-2014, 03:06 AM
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Quote:
Originally Posted by JFairman View Post
Vibration under load like your describing is probably one cylinder putting out less power than the rest. Do a compression and leak down test.
Compression check is quicker and easier and doesn't require an air compressor and leak down tester.
thats what i was thinking, cept more along the lines of maybe an air leak.
mine kind of did that when it had an air leak. just not quite as smoothe as it should be but i noticed it the most since i drive it the most,
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Old 05-27-2014, 06:49 AM
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I had to deal with vibrations to. Have a look to my thread and maybe it can help.
Mine was a pilot bearing missing!
If I had to give a score 1 to 10 how strong the vibration was then it would be a 10! But a worn out pilot bearing can be any number... like always it's guessing
Strong vibration gets worse at high rpm
Old 05-27-2014, 08:29 AM
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Mine used to have a slight vibration and audible uneven exhaust note to go with it under full boost when it had low compression in one cylinder because some valve guides were worn more than others due to some clogged cam spray bar holes and that caused the valve seats to wear. I thought it probably had some broken rings but when I took it apart they were all intact.

After rebuilding the top end with new Mahle pistons and cylinders, rebuilt heads with new guides, reground valves and valve seats, and balancing the resized connecting rods and the new piston and wrist pin assemblies seperately down to .1 gram on a triple beam it's incredibly smooth all the time.
Old 05-27-2014, 08:51 AM
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