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From: BSAKing on 9 Jul 2010 11:29 I have a 1976 vette with about 120K miles on it. Last year I had to do a fair amount of work on it (spring, shocks, rad support bracket, new rad, new water pump.). It seems to have been developing a problem and I am not sure what it is. I thought it started about the time I installed the new water pump, but that could be nothing more than sheer coincidence. It was making a sort of slight rubbing/banging/knocking noise, and I thought it was some minor machining discrepency causing a slight rubbing of the water and main pulleys. There was a rubbing sound that went away after a bit. Yesterday I had to replace a motor mount and tightened a bit of exhaust on the manifold. Today the noise is back. But now It sounds morelike a banging/knocking sound. The frequency increases with engine RPM. If I bring the engine up to a modest rpm and hold it there , it seems to go away. It seems worse when I first start it. Now I am obviously not expecting a thorough diagnostic from this description, but I am not a very experienced mechanic. Does it sounds like the symptoms of a main/crank bearing or something terminal of that nature? If so, I'm afraid old Betsy is doomed because I do not have the facilities nor the resources to get it repaired ...... FWIW, it still seems to run ok, oil pressure is normal, battery charging, water temp, shifting etc.... I went around it with a crowbar and using it on my ear as a poor man's stethoscope and was unable to pinpoint the source of the problem (so far)... It definitely seems to be coming from the bottom part of the front/engine somewhere..... Thanks for any input.
From: m6onz5a on 9 Jul 2010 11:38 On Jul 9, 11:29 am, "BSAK...(a)hotmail.com" <BSAK...(a)hotmail.com> wrote: > I have a 1976 vette with about 120K miles on it. > > Last year I had to do a fair amount of work on it (spring, shocks, rad > support bracket, new rad, new water pump.). > > It seems to have been developing a problem and I am not sure what it > is. > > I thought it started about the time I installed the new water pump, > but that could be nothing more than sheer coincidence. It was making a > sort of slight rubbing/banging/knocking noise, and I thought it was > some minor machining discrepency causing a slight rubbing of the water > and main pulleys. There was a rubbing sound that went away after a > bit. > > Yesterday I had to replace a motor mount and tightened a bit of > exhaust on the manifold. > > Today the noise is back. But now It sounds morelike a banging/knocking > sound. The frequency increases with engine RPM. If I bring the engine > up to a modest rpm and hold it there , it seems to go away. It seems > worse when I first start it. > > Now I am obviously not expecting a thorough diagnostic from this > description, but I am not a very experienced mechanic. Does it sounds > like the symptoms of a main/crank bearing or something terminal of > that nature? If so, I'm afraid old Betsy is doomed because I do not > have the facilities nor the resources to get it repaired ...... > > FWIW, it still seems to run ok, oil pressure is normal, battery > charging, water temp, shifting etc.... I went around it with a crowbar > and using it on my ear as a poor man's stethoscope and was unable to > pinpoint the source of the problem (so far)... It definitely seems to > be coming from the bottom part of the front/engine somewhere..... > > Thanks for any input. take a long screwdriver and place the tip on different parts of the motor and the other end against your ear, and see where it's loudest.
From: BSAKing on 9 Jul 2010 12:05 On Jul 9, 11:38 am, m6onz5a <corv...(a)comcast.net> wrote: > On Jul 9, 11:29 am, "BSAK...(a)hotmail.com" <BSAK...(a)hotmail.com> wrote: > > > > > I have a 1976 vette with about 120K miles on it. > > > Last year I had to do a fair amount of work on it (spring, shocks, rad > > support bracket, new rad, new water pump.). > > > It seems to have been developing a problem and I am not sure what it > > is. > > > I thought it started about the time I installed the new water pump, > > but that could be nothing more than sheer coincidence. It was making a > > sort of slight rubbing/banging/knocking noise, and I thought it was > > some minor machining discrepency causing a slight rubbing of the water > > and main pulleys. There was a rubbing sound that went away after a > > bit. > > > Yesterday I had to replace a motor mount and tightened a bit of > > exhaust on the manifold. > > > Today the noise is back. But now It sounds morelike a banging/knocking > > sound. The frequency increases with engine RPM. If I bring the engine > > up to a modest rpm and hold it there , it seems to go away. It seems > > worse when I first start it. > > > Now I am obviously not expecting a thorough diagnostic from this > > description, but I am not a very experienced mechanic. Does it sounds > > like the symptoms of a main/crank bearing or something terminal of > > that nature? If so, I'm afraid old Betsy is doomed because I do not > > have the facilities nor the resources to get it repaired ...... > > > FWIW, it still seems to run ok, oil pressure is normal, battery > > charging, water temp, shifting etc.... I went around it with a crowbar > > and using it on my ear as a poor man's stethoscope and was unable to > > pinpoint the source of the problem (so far)... It definitely seems to > > be coming from the bottom part of the front/engine somewhere..... > > > Thanks for any input. > > take a long screwdriver and place the tip on different parts of the > motor and the other end against your ear, and see where it's loudest. I went around it with a crowbar and using it on my ear as a poor man's stethoscope and was unable to pinpoint the source of the problem (so far)... It definitely seems to be coming from the bottom part of the front/engine somewhere.....
From: WW on 9 Jul 2010 13:10 <BSAKing(a)hotmail.com> wrote in message news:2982175b-0f04-4387-9103-2a0132ce06bd(a)c10g2000yqi.googlegroups.com... >I have a 1976 vette with about 120K miles on it. > > Last year I had to do a fair amount of work on it (spring, shocks, rad > support bracket, new rad, new water pump.). > > It seems to have been developing a problem and I am not sure what it > is. > > I thought it started about the time I installed the new water pump, > but that could be nothing more than sheer coincidence. It was making a > sort of slight rubbing/banging/knocking noise, and I thought it was > some minor machining discrepency causing a slight rubbing of the water > and main pulleys. There was a rubbing sound that went away after a > bit. > > Yesterday I had to replace a motor mount and tightened a bit of > exhaust on the manifold. > > Today the noise is back. But now It sounds morelike a banging/knocking > sound. The frequency increases with engine RPM. If I bring the engine > up to a modest rpm and hold it there , it seems to go away. It seems > worse when I first start it. > > Now I am obviously not expecting a thorough diagnostic from this > description, but I am not a very experienced mechanic. Does it sounds > like the symptoms of a main/crank bearing or something terminal of > that nature? If so, I'm afraid old Betsy is doomed because I do not > have the facilities nor the resources to get it repaired ...... > > FWIW, it still seems to run ok, oil pressure is normal, battery > charging, water temp, shifting etc.... I went around it with a crowbar > and using it on my ear as a poor man's stethoscope and was unable to > pinpoint the source of the problem (so far)... It definitely seems to > be coming from the bottom part of the front/engine somewhere..... > > Thanks for any input. Had a 56 T Bird and similar noise at lower front of engine. Turned out to be the vibration pulley on front of crankshaft. WW
From: jim on 9 Jul 2010 13:26
"BSAKing(a)hotmail.com" wrote: > > On Jul 9, 11:38 am, m6onz5a <corv...(a)comcast.net> wrote: > > On Jul 9, 11:29 am, "BSAK...(a)hotmail.com" <BSAK...(a)hotmail.com> wrote: > > > > > > > > > I have a 1976 vette with about 120K miles on it. > > > > > Last year I had to do a fair amount of work on it (spring, shocks, rad > > > support bracket, new rad, new water pump.). > > > > > It seems to have been developing a problem and I am not sure what it > > > is. > > > > > I thought it started about the time I installed the new water pump, > > > but that could be nothing more than sheer coincidence. It was making a > > > sort of slight rubbing/banging/knocking noise, and I thought it was > > > some minor machining discrepency causing a slight rubbing of the water > > > and main pulleys. There was a rubbing sound that went away after a > > > bit. > > > > > Yesterday I had to replace a motor mount and tightened a bit of > > > exhaust on the manifold. > > > > > Today the noise is back. But now It sounds morelike a banging/knocking > > > sound. The frequency increases with engine RPM. If I bring the engine > > > up to a modest rpm and hold it there , it seems to go away. It seems > > > worse when I first start it. > > > > > Now I am obviously not expecting a thorough diagnostic from this > > > description, but I am not a very experienced mechanic. Does it sounds > > > like the symptoms of a main/crank bearing or something terminal of > > > that nature? If so, I'm afraid old Betsy is doomed because I do not > > > have the facilities nor the resources to get it repaired ...... > > > > > FWIW, it still seems to run ok, oil pressure is normal, battery > > > charging, water temp, shifting etc.... I went around it with a crowbar > > > and using it on my ear as a poor man's stethoscope and was unable to > > > pinpoint the source of the problem (so far)... It definitely seems to > > > be coming from the bottom part of the front/engine somewhere..... > > > > > Thanks for any input. > > > > take a long screwdriver and place the tip on different parts of the > > motor and the other end against your ear, and see where it's loudest. > > I went around it with a crowbar > and using it on my ear as a poor man's stethoscope and was unable to > pinpoint the source of the problem (so far)... It definitely seems to > be coming from the bottom part of the front/engine somewhere..... Does the vibration damper (crankshaft pulley) look like it is running true? or does it wobble? Rubber does tend to fall apart after 35 years and they can knock when that happens. -jim |