Need Help Diagnosing Engine Problem (Video Included)

[Duncan McDougal]

I am trying to track down the root of the sound that my engine is making. It is a 88 GT. The sound only happens with when under load and increases with rpm and appears to be coming from the #4 cylinder/ throttle body area.

Here is the video of the video. YouTube - 5.0 engine noise

 

[Black1987Stang]

my vote is something in the bottom end, like with the piston ring assembly....do a compression and/or leakdown test and see what it comes out with. and give some more about how it happened, all of a sudden or after beating on it or something?

 

[Duncan McDougal]

It really just occurred in the last couple of days, I first noticed it on the way back from a road trip on saturday. I have never had a problem with it before and I was not beating on the car during the trip. I did a compression test and all the cylinders but 4 checked out (being in the service limit), number 4's compression was a high at 165psi but I just attributed that to carbon build up.

Edit: I also have not notice any lose in power. The engine still pulls strong. This is perplexing.

 

[tonyjr9108]

Do you have any drivability problems? Any loss of power? It's hard to tell what the noise is from the video, but have you checked the vacuum hose going to the smog pump?

 

[iapexl8r]

#1sounds like it could be a FUBAR smog pump.
#2or possible the flywheel/flexplate is coming into contact with the aluminum blockplate.

troubleshooting
#1 remove serpintine belt and try to rorate smog pump.

#2 warm engine up. turn it off loosen up bellhousing bolts(all of them)
re torque this should also fix problem

 

[Duncan McDougal]

I tested the smog pump and it is not it. I will have to check the transmission when I get the chance. Also I narrowed down the sound even further. It seems to be coming from the behind the intake area almost from the bellhousing.

Again, I don't seem to have any driveability problems. I don't have any loss of power and the compression check didn't turn up any problems.

Here are some more videos of the sound. You can really hear it will from underneath the car.

Engine Bay:
Engine

Underneath the Car by Transmission:
Under Car

 

[Black1987Stang]

Sounds like some kind of bearing....

5spd or auto?

If 5spd....possible bad throw out bearing? press in the clutch and does the noise change?

I would run it without the serpentine belt if you already haven't to rule out alternator, water pump, smog pump, etc...

 

[Duncan McDougal]

Sounds like some kind of bearing....

5spd or auto?

If 5spd....possible bad throw out bearing? press in the clutch and does the noise change?

I would run it without the serpentine belt if you already haven't to rule out alternator, water pump, smog pump, etc...

It is a 5 speed and I already ran it without the belt. The sound is definitely coming from the back of the engine and not the accessories. The sound also does not change when the clutch is depressed.

 

[93 LX]

bad TO bearing or bearing retainer. How does the clutch feel when you push down the clutch. Is it smooth or does it feel like it binding?

 

[Duncan McDougal]

It was the Pilot Bearing for any interested to know.

 

[93 LX]

did you do the clutch while you were there?

 

[Duncan McDougal]

No, can't afford clutch right now. I have a clutch and billet flywheel scheduled for December. I don't have to much of a problem with transmission jobs because my best friend's dad has a lift.