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How do you know if the engine mounts need replacing? I recently bought a 968 cab and it has a really odd buzzy vibration very noticeable through the gearshift stick as you approach 4000 rpm and just gets more intense as you rev higher. Not shaking, just a real buzzy buzz. The service history says a Porsche dealership recently corrected a balance shaft 180 degrees out. So maybe it's right or wrong. But my first thought was it feels like engine mount. But the service history says the engine mounts were replaced about 1 yr ago.
How do you know if the engine mounts need replacing? I recently bought a 968 cab and it has a really odd buzzy vibration very noticeable through the gearshift stick as you approach 4000 rpm and just gets more intense as you rev higher. Not shaking, just a real buzzy buzz. The service history says a Porsche dealership recently corrected a balance shaft 180 degrees out. So maybe it's right or wrong. But my first thought was it feels like engine mount. But the service history says the engine mounts were replaced about 1 yr ago.
Blown motormounts make the engine vibrate at idle. Out of balance bs pulleys make the engine buzz and not want to rev past 4k.
The shop got the bs pulleys wrong. I would almost guarantee that they are misaligned.
Thanks. I have the 924, 944, 068 wrksp PDFs; I will look for the recommended procedure. I am suspicious of the 180 degree reversal the Porsche dealer did, and the fact that I have this vib. But I don't know if the vib was there before the sprocket reversal - before my ownership.
From Clarks-Garage seems like I need to first check the sprockets are on the shafts correctly, then check that the sprockets are 'positioned' correctly on the toothed belt. I'm going to do a search for useful youtube content. Seems like to check the alignment of sprockets to shafts, that can be done with the covers on. Then to check alignment of sprockets to TDC, that needs the covers off.
Lol....I am either old or I can blame it on bad lighting but the ancillary belts and both covers come off for inspection/adjustment. Note that the lower balance belt tension can be correct in two positions but only one is correct for setting the gaps on the idler.
Last edited by thomasmryan; 11-19-2016 at 02:44 PM.
Reason: Istallation not instillation.
Lol....I am either old or I can blame it on bad lighting but the ancillary belts and both covers come off for inspection/adjustment. Note that the lower balance belt tension can be correct in two positions but only one is correct for setting the gaps on the idler.
Correct, the position that moved the BS belt away from the WP is the correct position.
So I'm starting in on checking the balance shafts alignment. Took the under trays off. Side note - I also want to track down why the underside of the engine has wet oil on it - hardly drips at all, but it is wet.
So I took the under trays off. The camshaft belt cover looks bone dry and clean - remember, the PO had front end work done, ending with his local P dealership 'resetting' the BS timing.
The power steering pump looks wet - ?
The sump is oily. The housing were the starter mounts is oily and has an oil drip on it. There is some assembly above the sump drain plug that looks very wet, and the pan gasket is wet on the passenger side and on the driver side.
So I'm starting in on checking the balance shafts alignment. Took the under trays off. Side note - I also want to track down why the underside of the engine has wet oil on it - hardly drips at all, but it is wet.
So I took the under trays off. The camshaft belt cover looks bone dry and clean - remember, the PO had front end work done, ending with his local P dealership 'resetting' the BS timing.
The power steering pump looks wet - ?
The sump is oily. The housing were the starter mounts is oily and has an oil drip on it. There is some assembly above the sump drain plug that looks very wet, and the pan gasket is wet on the passenger side and on the driver side.
Almost surely oil pan gasket. They get old, and then someone (like a dealer) does you a 'favor' and snugs the bolts up. Which causes them to leak. Do the MM job, but remove the crossmember. Use a cross brace support from above to hold the engine, then use a speed driver to pull all those oil pan bolts.
Contact Roger at 828sRUS.com for parts, he carries them all in stock. Clean, it repl the MM and do the balance shaft check yourself. Likely the shop got it wrong. If it still buzzes, investigate your torque tube bearings and rear end gears.
Engine area looks very clean as stated. The oil by the starter is from blow by from oil pan leaking, As far as the PS pump, it could be residual oil from changing the oil filter or the clamps/hose on the PS reservoir to pump section. The hoses are famous for flaring and leaking.
11-19-2016, 01:48 AM
