Pre ignition?
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Pre ignition?
On my 2000 E-450 SD V-10 Motor Home with about 80k that runs fine. It just started making a slight sound sort of like pre ignition around 2 to 3000 RPM under a slight throttle pressure, and any throttle pressure change will make it go away, lighter or heaver. And its not quite like pre ignition, its vary hard to hear. And better quality gas doesn't make it go away. It can also come and go on its one at a study cruise.
Could it have anything to do with the serp belt and what it drives including the idler pulleys, fan clutch Etc. Or any other ideas?
Thanks Mike.
Could it have anything to do with the serp belt and what it drives including the idler pulleys, fan clutch Etc. Or any other ideas?
Thanks Mike.
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I ran a search on piston slap, and from what I can tell that's not the problem. Its completely quiet on cold, or all start ups, and only makes this sound at around 2 to 3K RPMs when driving with the engine hot. It was doing it yesterday and it was 98* outside, with the AC on and had been driven for several hrs, and the scan-gauge read 198* engine temp. Im running 10W30 Mobil 1 oil, and it hasn't got 100 miles on this change.
Ill check the other suggestion. Thanks
Mike.
Ill check the other suggestion. Thanks
Mike.
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It's not piston slap at such a "high" RPM - the modular "piston slap" issue is usually during a cold-start, and as soon as you hit the gas, it warms up the pistons enough to make it go away.
Follow Monsta's advice
Follow Monsta's advice
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That's why I ruled out piston slap.
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I've been in a few vehicles while I was enlisted that had piston slap regardless of RPM, all that mattered was that the engine was holding a constant rpm with no engine braking or acceleration involved. Also, owned a 4.6L T-Bird that did the same thing.
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Would or could piston slap come on all of a sudden, like after 70K plus miles with no preignition, or piston slap before?
I stopped and get a half tank of gas at a station I have never stopped at before. I pulled back out on the freeway, and within 3 miles I started to hear this sound at a steady 55 to 65 mph, that sounds like a slight ping or preignition. Its not vary loud compared to any preignition I have ever heard before, and I have heard it before. It would start and stop at Cruise or under vary slight acceleration, and I could make it go away with a little more throttle or a little less. The fact that when under long hard low RPM loads, with heavy throttle pressure it never makes this noise is why I wonder if its preignition at all. This is a classic time when if its going to ping, it would, but it doesn't.
I think I need to check the heat shields as recommended, and other things. Changing gas octane has not eliminated the noise, so i'm guessing its not preignition or ping at all.
I did wonder what it sounds like to have a bearing go bad in a belt tensioner, or fan clutch, as I haven't had that happen, but its just a guess.
Mike.
I stopped and get a half tank of gas at a station I have never stopped at before. I pulled back out on the freeway, and within 3 miles I started to hear this sound at a steady 55 to 65 mph, that sounds like a slight ping or preignition. Its not vary loud compared to any preignition I have ever heard before, and I have heard it before. It would start and stop at Cruise or under vary slight acceleration, and I could make it go away with a little more throttle or a little less. The fact that when under long hard low RPM loads, with heavy throttle pressure it never makes this noise is why I wonder if its preignition at all. This is a classic time when if its going to ping, it would, but it doesn't.
I think I need to check the heat shields as recommended, and other things. Changing gas octane has not eliminated the noise, so i'm guessing its not preignition or ping at all.
I did wonder what it sounds like to have a bearing go bad in a belt tensioner, or fan clutch, as I haven't had that happen, but its just a guess.
Mike.
