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Few ????s. Piston Slap and Engine Knock

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Old 03-08-2005, 09:55 AM
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Default Few ????s. Piston Slap and Engine Knock

I bought my car with 18k on it and never heard the piston slap when I test drove it so it must have been warm. I now here the slap like everyone else, on a cold start and then again on warm restarts. But Just recently I heard it while I was under the hood ( I guess it was piston slap). The noise was very faint but still audible. My question is how many of you lucky piston slappers still have a little noise when your car is warm? I also switched from German Castrol 0w40 to Mobil 1 10w30 right before I started hearing the noise. Maybe this amplified it?

How loud does an engine knock with a spun bearing/bearing damage? Is it very noticeable or do you have to listen hard?
Old 03-08-2005, 10:01 AM
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I noticed when I switched to Mobil 1 the drivetrain noises got louder including what sounds like the piston slap. And yes, I can faintly here the sounds of the piston beating the crap outta my cylinder walls after it's warm now.

Next oil change, I think I'll be going back to dino oil.

With a spun bearing, you could have complete failure within minutes or the noise will be faint at first but progressively get worse. It's just a matter of time before complete failure.
Old 03-08-2005, 11:30 AM
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I am switching to syntec next change in 1K miles. My piston slap is noticable when VERY cold, but never when warm.
Old 03-09-2005, 03:02 PM
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Well I'll be switching back to German Castrol tonight so I'll see if that makes any difference. Thanks for the input guys.
Old 03-10-2005, 01:45 PM
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How many of those with piston slap can still here it faintly when warm? I can.
Old 03-10-2005, 02:15 PM
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I have 122,000 miles on my car and it just started making a knocking noise when it is cold, but when it warms up it goes away. I have always used Mobil 1 10-40, and never had a problem until about 120,000, then I started to hear it.
Old 03-10-2005, 02:18 PM
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Originally Posted by way2slow
How loud does an engine knock with a spun bearing/bearing damage? Is it very noticeable or do you have to listen hard?
You WILL notice a spun bearing. There will be no doubt there is a problem (it won't go for very long). Mine slaps a little when it's cold.
Old 03-10-2005, 03:53 PM
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I dont have any piston slap on my current WS6 but I had a 99 that had it on 2 engines. It was always worse when I ran synthetic oil. The dealer told me not to use synthetic and once I switched back it was quieter.

Best advice I can tell you is to beef up your air intake. My WS6 has a really loud whistle from the air going in to the engine and if I had any slap I probably wouldnt notice it over the whistle. Sounds like a jet engine when I rev it
Old 03-10-2005, 04:23 PM
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Originally Posted by PROGRESS
I dont have any piston slap on my current WS6 but I had a 99 that had it on 2 engines. It was always worse when I ran synthetic oil. The dealer told me not to use synthetic and once I switched back it was quieter.

Best advice I can tell you is to beef up your air intake. My WS6 has a really loud whistle from the air going in to the engine and if I had any slap I probably wouldnt notice it over the whistle. Sounds like a jet engine when I rev it
Thats interesting about the oil. I was told that it would be quieter with synthetic but it does seem louder. I changed to German Castrol last night and that didnt help one bit. I read all the advice about synthetics and found that German Castrol was supposed to be the end all of synthetics. What is the best dino?




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