Hello, I'm new to this forum so thank you all in advance for any help.
I just got my Dads old 96 4runner, limited, 3.4L about three weeks ago. I had a knock sensor harness start acting up about a month ago and replaced the harness and the sensors about 2 weeks ago. While I was at it I replaced the valve covers. I replaced all gaskets and injector o-rings. Buttoned it all up and went to start it and it now is making a very very loud clicking noise. Sounds like the valves normally do but 10x+ louder. I can pinpoint it to the engine, but it is loud enough it is hard to pinpoint farther than that on location. if I had to guess is would say cylinder 1. I tore everything that I had taken apart down again and put all back together and noise is still there. The third time of taking apart and reassembling noise did not start out harmonic, but random for 5 seconds then became harmonic again. I am about to pull the valves off and replace them and the seats, but hoping these is something else I am missing.
Details:
No codes thrown
Engine runs smooth
Sound is harmonic and changes with engine speed
Sounds like a valve click but much louder
Does not make sounds while turning over
Does not make sound when EFI fuse is pulled
Borescope each cylinder didn't show any signs of impact or loose debris
Pulled each wire and engine slowed, but noise still present
Pulled each plug and wire, engine slowed but still noise present
Did a compression test and a leak down test
Cyl 1: 145 psi. 22% leak at 87psi
Cyl 2: 160 psi. 18% leak at 87psi
Cyl 3: 155 psi. 22% leak at 87psi
Cyl 4: 150 psi. 15% leak at 87psi
Cyl 5: 155 psi. 22% leak at 87psi
Cyl 6: 160 psi. 20% leak at 87psi
Did a valve clearance test, all were within specs. Cyl 5 one exhaust valve was 0.001 high.
Vacuum test runs steady at 46cm Hg
Replaced plugs and wires.
And here is the frustrating part. Neighbor is a mechanic and rebuilds engines at the Lexus dealership in Dallas and he can't figure it out either.
I am open to all ideas and thoughts.
Thank you all for your responses
I just got my Dads old 96 4runner, limited, 3.4L about three weeks ago. I had a knock sensor harness start acting up about a month ago and replaced the harness and the sensors about 2 weeks ago. While I was at it I replaced the valve covers. I replaced all gaskets and injector o-rings. Buttoned it all up and went to start it and it now is making a very very loud clicking noise. Sounds like the valves normally do but 10x+ louder. I can pinpoint it to the engine, but it is loud enough it is hard to pinpoint farther than that on location. if I had to guess is would say cylinder 1. I tore everything that I had taken apart down again and put all back together and noise is still there. The third time of taking apart and reassembling noise did not start out harmonic, but random for 5 seconds then became harmonic again. I am about to pull the valves off and replace them and the seats, but hoping these is something else I am missing.
Details:
No codes thrown
Engine runs smooth
Sound is harmonic and changes with engine speed
Sounds like a valve click but much louder
Does not make sounds while turning over
Does not make sound when EFI fuse is pulled
Borescope each cylinder didn't show any signs of impact or loose debris
Pulled each wire and engine slowed, but noise still present
Pulled each plug and wire, engine slowed but still noise present
Did a compression test and a leak down test
Cyl 1: 145 psi. 22% leak at 87psi
Cyl 2: 160 psi. 18% leak at 87psi
Cyl 3: 155 psi. 22% leak at 87psi
Cyl 4: 150 psi. 15% leak at 87psi
Cyl 5: 155 psi. 22% leak at 87psi
Cyl 6: 160 psi. 20% leak at 87psi
Did a valve clearance test, all were within specs. Cyl 5 one exhaust valve was 0.001 high.
Vacuum test runs steady at 46cm Hg
Replaced plugs and wires.
And here is the frustrating part. Neighbor is a mechanic and rebuilds engines at the Lexus dealership in Dallas and he can't figure it out either.
I am open to all ideas and thoughts.
Thank you all for your responses
