960 rod bearing issue
960 rod bearing issue
I have a 1996 960 sedan. I just changed power steering pump, alternator, serpentine belt, tranny filter and oil change. At end of day I added 3 quarts of oil, all I had on hand and started car. It tapped for 4 or 5 seconds then ran smooth. I shut it off and went to bed. Next morning added 3 and a half quarts oil and started car it started knocking immediately. Afraid of the worst I ordered rod bearings online. I removed serpentine belt and started car, still knocking. What else can i check before tearing down this nightmare
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jimmy57
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Is the oil pressure light going off once engine starts?
DO you know for sure the knock is heavy and in lower end or is it a sharper rattle in top side of engine?
My suspicion is it is tappet rattle and will not go away until engine is held at 2000 RPM+ for 5 or more minutes. I think the 3 quarts may not have been enough and the oil got aerated and that takes time to purge from tappet. Aerated oil is compressible and makes for valve train tapping. This will not affect all tappets equally and wouldn't make them all rattle.
Rod bearing issues do not usually just instantly show up. IF you started it w/o any oil and ran it for 20 minutes I might suspect rod bearings. But in that case the noise would have been there before you shut it down. A hydraulic tappet with aerated oil with the cam depressing it to open valve will have pressure on it and the aerated oil leak out when normal pure oil supplied to tappet would not.
DO you know for sure the knock is heavy and in lower end or is it a sharper rattle in top side of engine?
My suspicion is it is tappet rattle and will not go away until engine is held at 2000 RPM+ for 5 or more minutes. I think the 3 quarts may not have been enough and the oil got aerated and that takes time to purge from tappet. Aerated oil is compressible and makes for valve train tapping. This will not affect all tappets equally and wouldn't make them all rattle.
Rod bearing issues do not usually just instantly show up. IF you started it w/o any oil and ran it for 20 minutes I might suspect rod bearings. But in that case the noise would have been there before you shut it down. A hydraulic tappet with aerated oil with the cam depressing it to open valve will have pressure on it and the aerated oil leak out when normal pure oil supplied to tappet would not.
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