Engine sounds like a steam whistle

I fired up my 1975 I6 258 yesterday and noticed a loud constant noise that sounds to me like an old groaning locomotive steam whistle. I idled the motor for a few moments, revved it briefly to see if it would go away and shut off the motor. The sound increased with RPMs and sounds like a metal on metal grinding squeal. When I killed the engine, I could hear a resonating metal sound as the motor came to a stop. I checked the oil and was a quart low (bad valve cover leak). I proceeded to replace the valve cover gasket and fill the oil, hoping it was just noise due to low oil. Today I fired the motor again and got the same result.

This motor was rebuilt by one of the PO and has been running well. I have put 30,000 miles on the engine since I bought it and have improved it's performance significantly with my mods. It burns a tiny bit of oil but no problems. I run a MSD distributor w/ MSD 6AL box, coil, and headers. Clutch has only 15,000 miles on it.

I checked the t-case and transmission fluid levels and it appeared that the tranny fluid was a little low, but the t-case was a little full. I figure this is normal since they are connected. Am I right?

100 miles ago I replaced my Rear Main Seal according to my Factory Service Manual instructions, lubed and torqued the rear main bearing cap to spec (80 ft/lbs). My oil pressure was initially high (70psi electric gauge) at idle, but after 50 miles or so it was idling at 20-30psi and increasing to 80psi w/ RPMs.


Does anyone have an idea where I should start? I can't think of any abnormal event while the motor was running recently. Can an engine break just sitting overnight?

Recent pic of motor:

Thanks for your help,
Mike

 

Check the easy stuff first. Remove the fan belts and start it up. See if noise goes away. May also be the starter not disengaged .

 

:iagree: Eliminate the external stuff first.

 

Excellent news. I popped off the Fan/Alternator belt and the sound is gone. Engine started right up and sounded normal. So, i guess that narrows it down to the water pump or alternator?

Something tells me the water pump might be the weak link here. How can I test each one of these?

 

Probably the water pump, easy way to check alt is to spin it by hand, feel smooth?? , or take it to advance, auto zone,etc. have them test it. One more question, were the belts ok and tight? Don't forget the power steering pump also., if you have one. Good luck.

 

Yep, belts were tight. The alternator and water pump are on one belt and the power steering pump is on a separate belt. I think for $23 I might put a new water pump on. When I grab the fan and wiggle it front to back there is a bit of play. Thanks.