First some background on the old problem: very neglected 225 had a bad grinding noise that could be felt through the gas pedal (and throughout the entire car at that). It would only manifest itself at partial throttle when the engine was under load (never when the car was stationary, ie: park or neutral).

I'm thinking now that with as bad of shape as the oil system in that engine is, it's possible that an oil passageway leading to a bearing is clogged and the bearing is rubbing against bare metal. I've picked up some 5W-30 synthetic blend and two quarts of ATF to flush out the engine the next time we change the oil, and then fill with 15W-50 Mobil 1 once it's done.

Just wondered if anyone had any other thoughts on the grinding just in case this doesn't at least alleviate it.

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'74 Duster w/ HEI ignition, beat to snot suspension, A904, 8.25" 3.55 SG rear, still being tuned up and gets 17 MPG

Know how they always build a better idiot? That's me

Sound or just a "feel"? If the latter, check your motor mounts. Also check the transmission dust cover.

D/W

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If it ain't broke, fix it!

Both. It sounds like metal on metal and can easily be felt when it occures.

Them motor mounts need to be replaced ASAP either way, though.

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'74 Duster w/ HEI ignition, beat to snot suspension, A904, 8.25" 3.55 SG rear, still being tuned up and gets 17 MPG

Know how they always build a better idiot? That's me

Could very well be trans related, too.

D/W

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If it ain't broke, fix it!

Metal-to-metal bearings generally won't grind on an ongoing basis. They'll knock and rattle, but not grind for more than about the last 10 seconds of the engine's life. Motor mounts, trans front pump, trans cooler lines.

DS

That's what I'm hoping this will help me find out for sure. I figure even if it doesn't alleviate the grinding, it'll at least clean out the oil passageways and help me better pinpoint where the grinding is coming from.

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'74 Duster w/ HEI ignition, beat to snot suspension, A904, 8.25" 3.55 SG rear, still being tuned up and gets 17 MPG

Know how they always build a better idiot? That's me

Also-

Ordinary Mobil-1 is not as good for our older engines as Mobil-1 Extended Performance.

That's the stuff I always use. 15W-50 Full synth is the way to be. Comes out clean as a whistle from my truck, even with as high as its engine's mileage is.

Though if the slant ever gets a nice thurough rebuild (doubtful now), I plan on 10W-40 full synth.

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'74 Duster w/ HEI ignition, beat to snot suspension, A904, 8.25" 3.55 SG rear, still being tuned up and gets 17 MPG

Know how they always build a better idiot? That's me

had this problem in the past. after days of crying like a baby and feeling hopeless I found out that the dipstick was rubbing against the crank. Somehow it bented and it was producing a very "blairwitchproject" scary noise.

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Juan Ignacio Caino

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