96 OHV Intermittent Chirp at Highway Speed

[trubbleinmind]

Hey all,

96 OHV, 212,000 miles

I've got a chirp every once in a while from behind the dash, usually when passing someone at highway speed, when the engine hits ~2200-2800 RPM. It sounds like it's coming from behind the tape deck, and I've heard it both when a tape is running and when there is no tape in the deck. Same with when the heat/air is on or off. I looked around here and elsewhere and figured it was the Camshaft Position Synchronizer so I replaced that with a Motorcraft CPS as well as the lower intake gasket and everything that goes with that.

The trouble is, I'm still getting the chirp every now and then. It stops as soon as I let off the gas, doesn't always come back right away when I get back on the pedal, and doesn't do it when I rev at idle, only when at highway speed. I thought maybe it was the oil pump so I installed a mechanical oil pressure gauge, but it didn't show any change in oil pressure when the sound came back. I really don't want to do the oil pump but I will if that's what it takes

Any thoughts on what else to take a look at would be much appreciated. Thanks!

 

[Tedybear]

Hey all,

96 OHV, 212,000 miles

I've got a chirp every once in a while from behind the dash, usually when passing someone at highway speed, when the engine hits ~2200-2800 RPM. It sounds like it's coming from behind the tape deck, and I've heard it both when a tape is running and when there is no tape in the deck. Same with when the heat/air is on or off. I looked around here and elsewhere and figured it was the Camshaft Position Synchronizer so I replaced that with a Motorcraft CPS as well as the lower intake gasket and everything that goes with that.

The trouble is, I'm still getting the chirp every now and then. It stops as soon as I let off the gas, doesn't always come back right away when I get back on the pedal, and doesn't do it when I rev at idle, only when at highway speed. I thought maybe it was the oil pump so I installed a mechanical oil pressure gauge, but it didn't show any change in oil pressure when the sound came back. I really don't want to do the oil pump but I will if that's what it takes

Any thoughts on what else to take a look at would be much appreciated. Thanks!

Have the same issue with our 95' Exp. I'll keep an eye on this one. It's always possible it's belt chirp or caused by tension/idler pulleys. (ran out of money for the time being....Might snag 'em off the yard junker when I'm there tomorrow.)

S-

 

[adsm08]

I'd take a look at the radio's volume control knob. This reads like it is set incorrectly.

Try turning it up and see if you still hear the chirp.

 

[trubbleinmind]

ooh, thanks adsm08, I'll check that out. the volume knob has never worked properly, won't turn off when depressed. I've got a weird farty noise from the radio only as well and was planning on pulling the unit soon to check it out anyway. I'll let you know what I find.

 

[RonD]

Unplug the AC compressor and try to get noise to come back.

Thinking it could be WOT relay cycling off and back on(chirp) the compressor.

Also I have found, like adsm08, that rolling down all the windows and having the Radio at full volume tends to "fix" any other noises issues

 

[trubbleinmind]

oh wait lol

I...get jokes...

 

[RonD]

 

[jeremysdad]

Unplug the AC compressor and try to get noise to come back.

Thinking it could be WOT relay cycling off and back on(chirp) the compressor.

Also I have found, like adsm08, that rolling down all the windows and having the Radio at full volume tends to "fix" any other noises issues

Volume knob fixed my power steering pump noise. Lol.

On topic, could possibly be belt or tensioner issue (in-line with your ac thoughts).

 

[adsm08]

Also I have found, like adsm08, that rolling down all the windows and having the Radio at full volume tends to "fix" any other noises issues

Yeah, turning the music up and the 2/70 AC cranked all the way is currently fixing my wife's wheel bearing. At least until I get the time to figure out which one it is.

 

[adsm08]

On a more serious note, take the belt off and turn it around so that it is spinning the other way. So if you drew an arrow on it pointing left before you took it off the arrow would face right after reinstalling the belt.

If this fixes or changes the noise the belt is worn out and causing the noise.

 

[trubbleinmind]

okay so I tried unplugging the A/C for my drive back from mom's house today. While it didn't eliminate the noise, it DID seem to significantly improve engine performance.

video of the sound:



https://www.youtube.com/watch?v=X-2w0AvZAws


I'll try the belt test tomorrow, though I changed the belt/tensioner ~12,000 miles ago. water pump maybe? I'll check that when the belt is off too

When the transmission was done ~5,000 miles ago they cut my y pipe and didn't repair it. I took it to a muffler shop and they said there wasn't enough there to weld, so they mudded it up but that obviously doesn't last long. Wondering if maybe the mud has cracked and it's the two sides of the pipe rubbing on each other? It increases in volume with RPM, but not in frequency.

Thanks to everyone for the suggestions!

 

[trubbleinmind]

idler pulley sounds awful when spun by hand. I'll change that soon and let y'all know if that stops the sound

 

[trubbleinmind]

changed the idler pully, pulled the stereo, hit the freeway, noise came back after a few miles. sounds way better at idle now though

BUT then I closed the middle vent doors and it didn't come back...now i'm thinking it's either the doors rattling with a certain highway vibration or something further down in the vents. no idea. oh well. what does a bad timing chain tensioner sound like on one of these?

 

[trubbleinmind]

is it detonation? it's hard to find a good youtube that shows what detonation/pinging actually sounds like. just a lot of people asking "is this detonation"? gahh

 

[trubbleinmind]

had a big cloud of smoke blow out from under the car while driving on the freeway today

might be time to go to a shop