No Smoking Gun

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bud L.

Post subject: No Smoking Gun

PostPosted: Tue Jul 30, 2002 8:28 am

I tore apart my 225 sl/6 last night. While there were several things I found wrong, I am not sure I found any 'smoking gun'.
To recap, the non original slant in my '66 Cuda has been making slapping/knocking noises, especially on start-up for years. A few months ago, on start-up it was noticeably louder than usual. I glanced at the mech. oil press. guage and it was zero and going nowhere. I nursed it 25 mi. home with the oil press. never exceeding 5psi.
I expected to see either a stripped oil pump gear and/or a spun crank/rod brg. Neither was the case.
I found that a previous owner must have rebuilt the engine: the rod caps had painted numbers on them. The rod and main bearings look new but are contaminated with debris(possible aluminum bits). The oil pump pick-up, while not totally blocked, did have a signicant amount of plastic pieces from the cam timing gear lodged in the pick-up screen. The chain was riding on the aluminum teeth of the cam sprocket, shredding the aluminum and (I think) contaminating the oil and the bearings. Because of the deteriorated condition of the timing gear, the chain had huge amounts of slack, which allowed the cam to walk forward and scrape the timing cover and oil slinger.
The rod caps & brgs were OK but #1 & #6 appeared to have less than ideal crush.
I have yet to examine the cam brgs to make sure one hasn't spun and covered an oil feed hole.
I haven't disassembled the oil pump yet to see if it can yield any more clues.
Did the oil pick-up just plug up with debris and starve the oil pump? I don't think so, because the pick-up screen was only about half covered.
Could the cam slide forward enough to disengage the oil pump drive gear, yet still drive the distributor and allow the engine to continue firing? I don't know. Any opinions?

fglmopar@aol.com

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Dart270

Post subject: Re: No Smoking Gun

PostPosted: Tue Jul 30, 2002 9:07 am

Quote:

: I tore apart my 225 sl/6 last night. While
: there were several things I found wrong, I
: am not sure I found any 'smoking gun'.
: To recap, the non original slant in my '66 Cuda
: has been making slapping/knocking noises,
: especially on start-up for years. A few
: months ago, on start-up it was noticeably
: louder than usual. I glanced at the mech.
: oil press. guage and it was zero and going
: nowhere. I nursed it 25 mi. home with the
: oil press. never exceeding 5psi.
: I expected to see either a stripped oil pump
: gear and/or a spun crank/rod brg. Neither
: was the case.
: I found that a previous owner must have rebuilt
: the engine: the rod caps had painted numbers
: on them. The rod and main bearings look new
: but are contaminated with debris(possible
: aluminum bits). The oil pump pick-up, while
: not totally blocked, did have a signicant
: amount of plastic pieces from the cam timing
: gear lodged in the pick-up screen. The chain
: was riding on the aluminum teeth of the cam
: sprocket, shredding the aluminum and (I
: think) contaminating the oil and the
: bearings. Because of the deteriorated
: condition of the timing gear, the chain had
: huge amounts of slack, which allowed the cam
: to walk forward and scrape the timing cover
: and oil slinger.
: The rod caps & brgs were OK but #1 & #6
: appeared to have less than ideal crush.
: I have yet to examine the cam brgs to make sure
: one hasn't spun and covered an oil feed
: hole.
: I haven't disassembled the oil pump yet to see
: if it can yield any more clues.
: Did the oil pick-up just plug up with debris
: and starve the oil pump? I don't think so,
: because the pick-up screen was only about
: half covered.
: Could the cam slide forward enough to disengage
: the oil pump drive gear, yet still drive the
: distributor and allow the engine to continue
: firing? I don't know. Any opinions?

My bet is that your slapping noise was the chain or cam hitting the timing cover. Also my bet is that the aluminum debris got lodged in the oil return spring, which is what caused your oil pressure to drop to zero. It wouldn't take much to stick that valve and PRESTO, zero oil pressure. I have seen this before on an engine with lots of metal crap/shavings in the oil sump. Sometimes, you can rev it up and dislodge the debris and free up the return valve. Your motor may be OK if you clean things up really well, including oil pump passages, rotor, etc, and bolt it back together - who knows...

Lou