Buzzing at high RPM FC Engine
 

I have a buzzing noise that is apparent in the cab of my B2200 when I shift gears at high RPM (5000RPM and above), the buzzing follows engine RPM. Its likely there when I am not shifting gears but the exhaust drowns it out.

To me it sounds like an oil pressure relief valve, I do have the engine solid mounted, and the B2200 has little if any sound insulation. My oil pressure is great, first startup when cold, my mechanical oil pressure gauge pegs at 100PSI, then settles to 25psi at 1000RPM, and at 3000RPM I am sitting at 60PSI, using 10W30 Synthetic oil. This engine is a S4/S5 TII engine, but with the 100PSI startup oil pressure, might have modified oil regulators, I am running the engine with all emissions removed, and no turbo.

Another possibility is the alternator, at idle under the hood, I can hear a slight amount of noise coming from it, but only if my head is close to it, otherwise its silent under there. I figure an alternator would make more of a squealing noise. I am using a double v-belt setup for the alternator and water pump.

Anybody else have a similar noise, or is it normal, my last engine (S4 N/A) did not make this noise, but it had a lower oil pressure, and didn't pass 45psi often, but I used the same alternator on it.

Truck has no air pump, no A/C, no power steering.

Unhook the alt and rev it up lol

I might have it figured out. When I first did my swap, I took the original oil cooler hoses to a hydraulic shop to have them extended to fit in my B2200, they welded on -6AN fittings to the original metal lines and banjo fittings, and I have been using the braided -6 lines. Looking online, everybody is using -10 lines, which is almost double the size. I think my noise is the front oil pressure regulator because the oil pump cant push enough oil through my -6 lines. Come to think of it, the sound is the same as when I started my old N/A motor when it was well below freezing, it was the front oil pressure regulator relieving pressure for a few seconds. I am going to upgrade this first, then test it, right now its snowing here so might be a day or 2.