76 problem - advice requested.

I have a 1976 vette with about 120K miles on it. Owned it since new.
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 more like 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.
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snipped-for-privacy@hotmail.com wrote:

On my '71 at about 75,000 miles, the vibration damper worked its way to the point where it was rubbing. It had to be replaced. That is a long time ago. Man, I miss that car.
Rather than a crowbar, I use a flexible piece of hose. Old pool vacuum hose is nice, as it is about 2 inches in diameter. I'd bet a piece of garden hose would work also.
Hope this helps.
--
Jim ( '93 40th Anniversary )

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hmm -If I am looking at the right part, when running it does not *seem* to run off center, but it does seem like the area where the noise is located (at least generallyt). I will have to try that swimming pool hose trick to see if I can further narrow it down (without lopping something off in all the turning and whirling things in that area....)
I wonder if it would be made worse by disconnecting the a/c drive belt? I did that since the A/c is not working and I only use it for scooting around with the top out. That make it pull more to one side and like you say - a 35 year old piece of rubber ...... maybe there is hope yet .....
Is that what the service manual would call a torsional damper? I have the factory service manuals here to help me along with things, but like I say, I am not a horribly experienced mechanic....
thanks
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May very well be your new water pump, easy to check by removing the belt and starting it up for a bit. It could just be your fan clutch and your engine can be run without it for some time if you keep it moving. Main bearings that are making a noise don't go away, they just get worse.
I would certainly look at what you just worked on first if it came right after that effort. Don't neglect the harmonic balancer, the inertia rings do come loose at times. Someone had replaced the steering idler arm on my '64 and had one with a zerk fitting that was hitting the exhaust pipe that made you think rods were knocking. It to would change the knock with engine RPM.
As a make shift stethoscope I use a tubular golf club handle, head removed, to pinpoint the noise. The soft grip is easy on the ear. ;-))
Good luck and let use know what you find.
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Thanks - it will take me a few days to get to it due to other things going on here. I think I will take off the fan and all belts so I can get in there with better safety with a chunk of pool hose to see what I may be able to determine....
Keep you posted......
BSA
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That many miles has in the past caused the fuel pump pushrod to wear and cause the type noise you are hearing. Try getting something (golf club, hose, whatever) on the fuel pump and you will probably hear the slap, knock of the rod. Not too hard to repair nor too expensive. There is a bolt in the front of the block that can be removed that normally holds nothing but, if you screw a longer bolt just snug it holds the rod in place while you remove and then to replace the pump. Before the bolt hole was cast into the block it was a real pain to do. Get a new rod, gaskets for pump and mounting plate and some gasket cement and go for it.
Good luck PDDeen

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That many miles has in the past caused the fuel pump pushrod to wear and cause the type noise you are hearing. Try getting something (golf club, hose, whatever) on the fuel pump and you will probably hear the slap, knock of the rod. Not too hard to repair nor too expensive. There is a bolt in the front of the block that can be removed that normally holds nothing but, if you screw a longer bolt just snug it holds the rod in place while you remove and then to replace the pump. Before the bolt hole was cast into the block it was a real pain to do. Get a new rod, gaskets for pump and mounting plate and some gasket cement and go for it.
Good luck PDDeen
Now there's a good one I forgot, been with the electric fuel pumps to long. http://www.classiccarauto.com/impala/how_to/replace_chevy_fuel_pump.shtml Good picture direction although it looks like an old front mounted SBC so the hole to retain it wasn't/couldn't be used. A new fuel pump and rod may be in order at this age, yours will have a bigger canister. Also the hose should be replaced. Fitting wrenches are a must. Both the fuel pump and the rod from https://www.rockauto.com/ can be less than $50.
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Good example of not knowing what all the bolts on an engine are for. The '64 Impala would have the bolt I referred to as well as the 305 small block. The only one I can not remember seeing it on was a '56 Vette and it may have been because of the engine mount plate.All of the later mechanical pump engines should have the bolt. It is around the corner to the front of the block and looks like it has a large flat washer on it. As I remember it is't a flat washer but is a fiber washer. Bolt is @ 1/2" and I used a 1" tightened finger tight only. I just needs to hold the bolt during assembly.
YMMV
Paul
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Good example of not knowing what all the bolts on an engine are for. The '64 Impala would have the bolt I referred to as well as the 305 small block. The only one I can not remember seeing it on was a '56 Vette and it may have been because of the engine mount plate.All of the later mechanical pump engines should have the bolt. It is around the corner to the front of the block and looks like it has a large flat washer on it. As I remember it is't a flat washer but is a fiber washer. Bolt is @ 1/2" and I used a 1" tightened finger tight only. I just needs to hold the bolt during assembly.
YMMV
Paul
That's what intrigued me about the pictures in the repair site. As far as I know the only front mount SBC was '55, '56, and '57. The Impala didn't exist then. Strange pictures with the wood frame and all. I never had to use that bolt to retain the push rod but only changed 4 or 5, the last being on a '73 Chevy van while on vacation.
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Sorry it took me awhile to find time to get to it, but ....
Well, well, well - here's the skinny!
I disconnected all the belts and fired it up and it makes normal noises for a 35 year old engine!
I hooked them up one by one and the noise was still gone. However, more closely examining everything, the head of the bottom mounting bolt for the power steering pump has snapped off. That allows some degree of movement and hence the clanking noises I hear I think.
Trying to remove it, it is in a different position so does not seem to wiggle. I fired it up and sure enough - the noise seems to have gone away.
Now to effect a permanent fix, I need to see if that bottom bolt screws into the mount assembly somehow or whether it can be punched out. Looks like I may have to disconnect and remove the power steering pump.
If I can do that and the noise has disappeared for good, I am a happy camper, but I will not know until I get there I guess.....
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.
Good grief - it never rains but it pours.....
The bolt slides thru the steering pump body it seems, but there is a spacer nut on the back - too thin to get a wrench on and it is holding the power steering pump to the bracket. If I try to spin it out, it locks the bracket tighter to the pump body.
I have the alternator and steering brackets off, but I cannot get the damned thing loose. If it were loose I could spin the bolt thru and replace it. And of course the head is snapped off so I cannot just break it loose.
The power steering hoses are frozen to the assembly under the car so it will be really tough to try to get all that loose and remove it all..
What to do? (Be gentle - I am no expert and admit it) .......
| | PS Pump| ===|[]======= <- Bolt thru pump body | | | | Nut holding bolt on (frozen to it) Power steering Bracket
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wrote: Snip Good grief - it never rains but it pours.....
The bolt slides thru the steering pump body it seems, but there is a spacer nut on the back - too thin to get a wrench on and it is holding the power steering pump to the bracket. If I try to spin it out, it locks the bracket tighter to the pump body.
I have the alternator and steering brackets off, but I cannot get the damned thing loose. If it were loose I could spin the bolt thru and replace it. And of course the head is snapped off so I cannot just break it loose.
The power steering hoses are frozen to the assembly under the car so it will be really tough to try to get all that loose and remove it all..
What to do? (Be gentle - I am no expert and admit it) .......
| | PS Pump| ===|[]======= <- Bolt thru pump body | | | | Nut holding bolt on (frozen to it) Power steering Bracket
=============================================================== Well there is no room to slide it off but isn't the entire pump and bracket held on by 2 bolts into the block. If that is so it seem like by removing those 2 bolts you can work on fixing the broken bolt on the bench. Remove the bracket bolts and then slide the pump off the broken pivot bolt to repair the bracket on the bench. I assume that "frozen nut" is welded to the bracket.
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Yes You are correct - I have had all of that off to try to give me more room to manoeuver. The kicker is that the fittings for the power steering are seized on with time and I am afraid I will bugger them up in the process. That is preventing me from taking the whole thing out. I warned you I am not a master nor experienced mechanic......
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No - The frozen nut is frozen to the bolt stub between the pump body and one side of the bracket. Were it not there, or turning, I could remove the bolt.
I think originally they have a bolt and use the small nut to lock the pump in place to one side of the bracket. Then there is a nut that goes on the other side of the bracket to secure it to that bracket side.
Wish could post pics on these groups - would make it much easier.....
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snipped-for-privacy@hotmail.com wrote:

post the pictures to something like picturetrail.com, then post the links here
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Use this site to make a pic with a link.
http://www.pixentral.com /
-W
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wrote in message news:666ad6d3-c327-40e4-b9cb-

And then link the pic here. Like so........
Ex: This is what your rear ed could look like someday.. :)
http://www.pixentral.com/show.php?picture=1k225m8FvkfgZSTvcxqN4iNNthz87c
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Thanks - maybe this will make things more clear...
http://www.pixentral.com/show.php?picture ZRwR4WIyatJcjc6PvADsiopuw1
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And the answer is! .....
It looks like The 63-74 pump had a hole thru the pump and a long bolt like in your drawing you posted earlier. the 75-82 had a short bolt in front and a stud in back. Both pumps will fit in the same bracket.
The stud on the back side of the pump does have a thin nut on it. The thin nut is part of the stud so it is not going to unscrew. If you look closely that bracket hole next to the thin nut is slotted. That slot is so the pump can slide out of the bracket without removing the stud with the small nut. But you do have to unbolt the bracket from the engine to get the pump out of the bracket.
Are you sure the bolt in front is broken? It could be just missing. This is what the stud in back looks like:
http://tinyurl.com/3ad5btr ==========Well - Jim - thank you very much!
I dug around today and it took me awhile to get it, but it was a bolt missing! I had to take it out of the bracket to make sure it would thread and you have to get it *just so* to start properly, but my car is running again without sounding like a run away garburetor. Best of all, old Betsy lives to ride another day!
I was pretty leery the way it sounded with the banging - it really did sound like a major engine issue....
Many thanks to you and others who so freely share their expertise with folks like me who, while not exactly mechanically challenged, certainly don't have the experience base others do.
Thanks again everyone!!!!
(Now to see why the carb secondaries do not seem to be operating and a tune up, and some front end parts to tighten up the steering, and... and... and ....)
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