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Joined: Dec 2007
Posts: 50 Likes: 1
Shade Tree Mechanic
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OP
Shade Tree Mechanic
Joined: Dec 2007
Posts: 50 Likes: 1 |
Hello All,
What could be cause the rods to loosen up on a 47 Chevy 216 Engine. I had the rods and mains tightened up in the fall of 2009. The car has gone about 2,000 miles since then and I can start to hear some rod knock at low speeds when the engine is warmed up. Is there any reason why the rods would loosen up this quickly? I have driven it on a couple of 200 mile tours over the past year and a have not gone faster than 55 MPH.
Thanks for your help.
Perol
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Joined: Jan 2010
Posts: 648
Oil Can Mechanic
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Oil Can Mechanic
Joined: Jan 2010
Posts: 648 |
Hows your oil preassure? Just curious.
In my shop, quality is a standard, NOT and option.
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Joined: Apr 2008
Posts: 1,194
ChatMaster - 1,000
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ChatMaster - 1,000
Joined: Apr 2008
Posts: 1,194 |
Maybe they have the dipper backward? Or possibly the troughs in the oil pan are out of adjustment?
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Joined: Jan 2002
Posts: 30,701 Likes: 141
ChatMaster - 25,000
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ChatMaster - 25,000
Joined: Jan 2002
Posts: 30,701 Likes: 141 |
Crankshaft out of round, babbitt breaking away from rod, Drop pan and see if the oil line to that rod is plugged-up....with garden hose water pressure.
Oil pressure will have ittle to do with it as the rods are "oiled" by the low pressure side of the system.
Gene Schneider
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Joined: Jan 2010
Posts: 648
Oil Can Mechanic
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Oil Can Mechanic
Joined: Jan 2010
Posts: 648 |
Yea...but if your pumpin little to no oil to the reservors...that would be a problem.
In my shop, quality is a standard, NOT and option.
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Joined: Dec 2007
Posts: 50 Likes: 1
Shade Tree Mechanic
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OP
Shade Tree Mechanic
Joined: Dec 2007
Posts: 50 Likes: 1 |
Gene,
The engine was be recently rebuilt (5 years ago) and the oil line was ok as of 2009. It does have the original babbit in the rods and they looked ok as of 2009.
I am really frustated because I thought I solved the problem when I tighten all the rods and mains in the fall of 2009. I am just beginning to hear some rod knock between 30 - 40 MPH.
Thanks for your help.
Perol
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Joined: Sep 2010
Posts: 29
Grease Monkey
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Grease Monkey
Joined: Sep 2010
Posts: 29 |
Piston slap??? Wrist pin? The slap thing is common. I first encountered it on a rebuilt 216.
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Joined: Jan 2002
Posts: 30,701 Likes: 141
ChatMaster - 25,000
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ChatMaster - 25,000
Joined: Jan 2002
Posts: 30,701 Likes: 141 |
Gene Schneider
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Joined: Sep 2002
Posts: 2,323 Likes: 6
ChatMaster - 2,000
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ChatMaster - 2,000
Joined: Sep 2002
Posts: 2,323 Likes: 6 |
A rod knock would be obvious just reving it a little with the car sitting still. Just as the RPM peaks and starts to drop off, a loose rod will be heard for a split second.
A knock from a main really shows a difference when load is applied.
I had a bent rod in my 216. When I put it under heavy load at highway speed it made a sqeaking sound as the piston hit the cylinder wall. The tell tale sign was the wear marks on the piston sides were sort of on a diagonal rather than straight.
My 1951 1 Ton is now on the road! My 38 Master 4 Door is also now on the road .
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