Strange engine noise?

MikeUrban

Member
May 30, 2010
187
1
19
Chantilly, VA
Hey guys. I have an 88 5.0, bone stock with 91,000 miles. When I got the car a couple weeks ago it had a little bit of a lifter tap, so I changed the oil and the noise went away. For a couple days everything sounded absolutely fine.

So I was driving to school last night and the engine started making this weird noise once it got hot, the best I can explain it as is driving on wet pavement. It's not loud or anything, and at certain rpms the exhaust makes it impossible to hear. However, no matter what the engine speed is or if the car is moving or not it makes no different, same noise. I've tried taking video but my phone can't pick it up very well because the noise is faint, and the exhaust is the only thing you can hear in the video.

Under the hood it sounds like it's coming from the passenger side, and behind the distributor. It's so strange.. I suspect it's the water pump or some other accessory but I can't tell. I doubt it's the p/s pump because it's on the complete opposite side of the engine bay. I wan't to go mass air, and gt40 top end with a cam and injectors.. but with this I don't feel comfortable doing it. Has anyone ever had this problem? Thank you!
 
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It could be the timing chain or a problem with your distributor/ bad sparkplug wire. Is it a tapping sound? or grinding sound? or hissing sound?
 
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More of a hissing sound. I plan on changing the cap/rotor/plugs/wires this weekend, cause it needs it anyway. Also there's a constant electrical sounding buzz when the car is running that isn't the fuel pump, but it kinda sounds like it's supposed to be there haha
 
You may have an exhaust leak or a vacuum leak..plus is the buzz/electrical sound coming from the dash/gauge area when you have the lights on?
 
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Hmm, I didn't think about an exhaust leak! That would explain it making more noise when it's hot. I'll check that out. The buzzing noise is 100% constant under every condition, and it isn't the radio because it and the speakers don't exist hahaha.
 
No it starts great, and doesn't have any kind of power loss whatsoever. Thanks for your help jka and jc, I'll check out all of your suggestions this weekend. I really am leaning towards an exhaust leak, its just that it doesn't have that distinct 'tisk tisk' noise they usually have.
 
2 other things...
You might be hearing the flutter of the PCV.
Especially if the valve is not seated well, or the hose going to it is soft.
My son's hose sucks shut sometimes and makes the oddest sounding flutter kind of noise. You can hear it over the engine at idle and some rpms.

Another...
Pop off the top of the distributor cap, and make sure the cap adapter that bolts to the base of the dizzy is not loose, and that both bolts are in place. We had one of the bolts work loose and fall out, then start bouncing around inside the dizzy until it destroyed the dizzy itself.
I now threadlock those 2 screws, even though I have never seen anything like that happen before. While you are there, make sure the 2 spring clips were both in place and seated properly.

Are you sure it isn't a bearing going bad in an idler pulley?
 
Those are all very good ideas! I can't wait to catch a break in the weather and start trying to figure this thing out. And I'm not sure at all if it's a bearing about to let go, is taking the belt off and checking for play on the pulleys a good way of testing that?
 
Taking the belt off and turning the accessories by hand is a good idea. Everything should spin smooth. I found a noisy idler pulley that way.

That ended up being my problem after getting rid of the clutch fan, replacing with an electric fan. I kind of knew it wasn't the issue, but it was my way of convincing my other half that I needed to change to an electric fan :)
 
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Just a little update. The car has started having an intermittent miss, so I'm thinking I have an ignition issue. I'll change the cap, rotor, plugs, and wires and see what it does. I've just been busy trying to get my friend's Turbo 5.0 volvo running (more on that soon ;) )
 
Get a stethoscope from HF Tools for when it comes back. Or get a really long screwdriver to listen with. The steth. Is worth every cent to track this stuff down.
 
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