M38A1 Engine Chirping Noise
Posted: Sat May 17, 2025 8:26 pm
Hey guys! Long time listener - first time posting. Newly rebuilt F134 engine (stock, 24 volt, with fording plumbing in normal position), of which I did all the work minus decking the block, so I worry every second I did something wrong.
During the 15 minute break in of the engine (doing the rebuild engine break in as spec'ed in the TM) I'm getting a weird chirping chittering noise. It really sounds like it is from the generator side. It sounds exactly like a fan grazing against radiator fins! But my fan has perfect clearance all around and there is no damage to the rad that I see. Stethoscope to the WP, Rad hoses, generator, and anywhere else didn't amplify the sound. Increasing rpm either drowns out the noise or makes it go away. I hope it's just an old fan belt, but I never heard a belt make a noise like that.
Just wondering if anyone has heard anything similar, my searches came up unfruitful. I had to pull the rad to fix a leak on the timing cover so wanted to ask while I'm still in the process of hanging parts. Link is below. I've seen YouTube links here before so I hope it's okay with the mods, let me know.
Thanks all!
https://youtube.com/shorts/q0ZfmN_QgGc? ... wB7wMA76ao
During the 15 minute break in of the engine (doing the rebuild engine break in as spec'ed in the TM) I'm getting a weird chirping chittering noise. It really sounds like it is from the generator side. It sounds exactly like a fan grazing against radiator fins! But my fan has perfect clearance all around and there is no damage to the rad that I see. Stethoscope to the WP, Rad hoses, generator, and anywhere else didn't amplify the sound. Increasing rpm either drowns out the noise or makes it go away. I hope it's just an old fan belt, but I never heard a belt make a noise like that.
Just wondering if anyone has heard anything similar, my searches came up unfruitful. I had to pull the rad to fix a leak on the timing cover so wanted to ask while I'm still in the process of hanging parts. Link is below. I've seen YouTube links here before so I hope it's okay with the mods, let me know.
Thanks all!
https://youtube.com/shorts/q0ZfmN_QgGc? ... wB7wMA76ao