The other day I drove about 90 miles and my 1994 Toyota 22RE 4x4 with 175,000 started making a weird metal dinging sound when I got it up to around 70 MPH but would stop when the RPM's were lower. It sounded similar to what a metal fan blade hitting metal would sound like although I don't have a metal fan. It did this in 4th and 5th gears but when I pushed in the clutch and revved the engine high the noise would stop. There was also a significant loss of power, especially going up hill when the noise was the worst. I was able to get it home that day (another 90 miles back) and of course when I had my mechanic drive with me the next day the noise wasn't there. He seemed to think it was in the transmission because the noise wasn't there when I revved the engine in neutral. We drained and changed the tranny oil and transfer case oil and there were no big metal shavings in there. I took it to another mechanic today and same thing, the noise was gone. It was suggested that the fuel may have been bad. Is this possible? The truck still runs strong like nothing happened. The clutch was changed at 100K; the head gasket, timing chain were replaced at 124k and at this time the valves were adjusted and cleaned. Any idea what this is? I'm stumped...

 

Did it sound like the engine was pinging? That's the only thing that comes to my mind. Check your timing and see if it's in spec.

 

Sounds like a transmission to me, I had a mazda that did it too, and there was no fragments in the oil even after it went.

 

You're clutch might be coming apart. What brand of clutch was used? There are little springs or rubber bushings in the clutch disc and they sometime fail and come out and bang around in the clutch assy. You could have a loss of power from the clutch holding due to debris

 

Sounds more like a metal fluttering sound at higher RPM's if that makes sense. I talked to another mechanic this evening and he said it might be pre-ignition since the engine does it under stress. The cause for this, according to him, might be the low octane (85) gas that I filled up on an hour before it happened. After asking around a little more it seems like this place is notorious for having cheap crappy gas. No wonder it's 5 cents cheaper. Drove the truck hard for 80 miles or so yesterday and another 60 miles today to burn out the old gas and to try to hear the noise again. But I had no more weird sounds. Then I filled up with higher octane stuff today drove around a bit and the truck has still not made the metal fluttering sound.
I'm not sure what brand clutch I have but it still seems strong as does the transmission. I'd like to think the problem is gone but I have never heard a weird sound like this in my 10 years of owning the truck and I'm getting ready to go on a long trip. I appreciate the help. Thanks.