Strange rattle
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Joined: Jun 2004
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From: Sweden
Strange rattle
Got an '87 E150 van, auto tranny, 302.
When I'm cruising between 55-65mph, a distinct rattle comes up. No drivability problem, everything feels normal, but the sound's got me worried. It's not in the drive train, when I put it in Neutral the noise stops. And I can rev up and hear it, and it's not tied to how much gas I'm giving it, just the RPM. Sometimes it goes away, sometimes it's louder, but that RPM range is a persistent feature. Sounds fine outside this range (above 65 mph it goes away).
It's not lifter chatter, it's too chaotic. The noise's rate doesn't go up and down with the rpm really. Sounds kinda like rainwater dripping off the roof into sheet metal. Like a rattling bearing. Timing chain noise sounds like a good description too, but I replaced the TC like 20,000 miles ago.
It doesn't change with steering or turning on the AC, and I replaced the water pump after this problem started with no effect. So if it's not in the engine it'd have to be alternator or smog pump but IMHO it's kinda loud for something like that.
I DO have a bad fan clutch. It's locked tight against the shaft when the engine's off and cold. I'd be more suspicious if there was more of a "screech" but this rattle doesn't sound quite right for that. It's on my list anyways.
I went looking for the problem after I started hearing it. I saw nothing unusual under the hood anyways. There's a water leak around the thermostat that concerns me (I thought it was from the water pump which is why I replaced it). For the type of sound I heard, it could have been fluid leaking out, but for the rate and volume it's have to be spraying and there's be oil or coolant or whatever all over the place. It's far too clean and I've not been losing water fast enough for that to be making that kind of sound.
Any ideas?
When I'm cruising between 55-65mph, a distinct rattle comes up. No drivability problem, everything feels normal, but the sound's got me worried. It's not in the drive train, when I put it in Neutral the noise stops. And I can rev up and hear it, and it's not tied to how much gas I'm giving it, just the RPM. Sometimes it goes away, sometimes it's louder, but that RPM range is a persistent feature. Sounds fine outside this range (above 65 mph it goes away).
It's not lifter chatter, it's too chaotic. The noise's rate doesn't go up and down with the rpm really. Sounds kinda like rainwater dripping off the roof into sheet metal. Like a rattling bearing. Timing chain noise sounds like a good description too, but I replaced the TC like 20,000 miles ago.
It doesn't change with steering or turning on the AC, and I replaced the water pump after this problem started with no effect. So if it's not in the engine it'd have to be alternator or smog pump but IMHO it's kinda loud for something like that.
I DO have a bad fan clutch. It's locked tight against the shaft when the engine's off and cold. I'd be more suspicious if there was more of a "screech" but this rattle doesn't sound quite right for that. It's on my list anyways.
I went looking for the problem after I started hearing it. I saw nothing unusual under the hood anyways. There's a water leak around the thermostat that concerns me (I thought it was from the water pump which is why I replaced it). For the type of sound I heard, it could have been fluid leaking out, but for the rate and volume it's have to be spraying and there's be oil or coolant or whatever all over the place. It's far too clean and I've not been losing water fast enough for that to be making that kind of sound.
Any ideas?
Thread Starter
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More Turbo
Joined: Jun 2004
Posts: 690
Likes: 0
From: Sweden
Kept trying to check it... but it wouldn't happen in the driveway.
Closed hood. Revved. Finally heard it again.
Then, flash of insight- popped the hood while I had it at the rpm where it rattled.
Sound stopped.... well that was easy to diagnose.
Closed hood. Revved. Finally heard it again.
Then, flash of insight- popped the hood while I had it at the rpm where it rattled.
Sound stopped.... well that was easy to diagnose.
