# Odd Rattle



## chuckha62 (Apr 5, 2010)

So, my wife and I were in the Goat the other day when we pulled up next to a car at a stop light. My wife commented that the car next to us was making an odd rattling sound. I agreed and then realized that it was not the car next to us, it was us.

I pulled over, opened the hood and listened. It sounded at first like maybe the water pump or the fan clutch was going out, so I turned around and took the car home. Once I got home, I shut it off and spun the fan and it was fine. I took the belts off and spun the water pump and it feels fine. I then put the belts back on and got out my stethoscope and tried to find the noise. I listened to the water pump, the alternator, the PS pump, the front cover right behind the balancer and couldn't hear anything that sounded like the rattle. I then put my probe on the valley cover right between intake runners and heard it. I then checked further back and nothing. It is definitely towards the front of the engine and higher up. The odd thing is that the noise goes away as soon as you're off idle and comes back when its at 600 RPMs or so

What the hell? Is there a thrust plate on the front of the cam? As far as I know there is just the fuel pump eccentric on the front of the cam. I can't hear the noise on the fuel pump, just towards the front of the valley pan.

Any ideas? I mean, I know I'm going to have to tear her down, but I'd like to know if any of you have experienced anything similar?

Thanks all!

Chuck


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## geeteeohguy (Feb 2, 2008)

Run it briefly without the belts to eliminate a water pump/spacer plate issue. It could be the fuel pump, fuel pump eccentric, or loose plate at the front of the cam. All easily reached once the timing cover is off. Could be a loose timing chain, but it would have to be _really_ loose. It could also be a PCV valve, but that is in the back of the VP on a '67. Could also be a lifter. Process of elimination. Good luck, and keep us posted!


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## jetstang (Nov 5, 2008)

I'm thinking losing a cam. Good luck. Is it a click or other noise?


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## BearGFR (Aug 25, 2008)

My first thought was PCV valve, but then on my 69 the valve is at the front of the cover right where you're describing. Sound can do funny things when it travels through metal. What kind of lifters are you running? 

Bear


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## chuckha62 (Apr 5, 2010)

Thanks guys! Ya know, I call it a rattle, but it's a little more solid than a click. It sounds to me to be in the area at the front of the cam, timing gear, f/p eccentric. If there is a retaining plate for the cam, then I bet it has come loose and is letting the cam walk a little bit. It's been so long since I've been into a Pontiac, that I don't remember that assembly. I guess I'll find out in the next few days...


More to come,

Chuck


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## geeteeohguy (Feb 2, 2008)

Chuck, it looks like a 1/8" thick steel thermostat gasket, but a bit smaller. What kind of _oil_ are you running? You could pull the valve covers and see if you are indeed losing a cam lobe. These cars _must _have ZDDP. Or at least check out the pushrods/rockers, etc. 4 bolts each side, quick and easy to do......


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## BearGFR (Aug 25, 2008)

One key question is, does the noise happen "in time" with the engine? Same rhythm, evenly spaced, and does "follow" with rpm (until the sound stops that is). If so, then I think you're on the right track. I'd still pull the valve covers first and check because that's easier than pulling the timing cover.

Bear


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## chuckha62 (Apr 5, 2010)

BearGFR said:


> One key question is, does the noise happen "in time" with the engine? Same rhythm, evenly spaced, and does "follow" with rpm (until the sound stops that is). If so, then I think you're on the right track. I'd still pull the valve covers first and check because that's easier than pulling the timing cover.
> 
> Bear


No, it is not in any particular rhythm and it's definitely not coming from the valve train. I've diagnosed wiped cam lobes before and this isn't anything like that. As far as oil goes, I use a ZDDP additive with every oil change (which I last did in May).

I don't think I'm going to fire it up anymore, until it's fixed. I'd hate for something minor to become something major. I'm betting that the cam retainer has come loose. It's about the only thing that would explain the inconsistent rhythm and coming and going under a change in load. I'll find my balancer puller and get into it next week. I wanted to remove and properly clearance my water pump anyway, I'll just have to go a little deeper, I guess. 

Thanks for the help guys! I'll keep you all posted.


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## BearGFR (Aug 25, 2008)

chuckha62 said:


> I don't think I'm going to fire it up anymore, until it's fixed. I'd hate for something minor to become something major.


Wise move I think. If it's the retainer, you sure don't want a bolt to rattle out and fall down into the pan where it can plan pinball with the crank. 

Beart


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## geeteeohguy (Feb 2, 2008)

X2. And be really careful not to drop anything down the front of the oil pan when you have the cover off. Not a bad job, really, and you can check out the timing chain, too. Keep us posted!!


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## chuckha62 (Apr 5, 2010)

Okay, here's what I've found... The cam retaining plate is not loose. The timing chain is a double roller and is in excellent condition, as are the gears and teeth. The cam bolt is tight and the eccentric is nice and tight. Now, I've been able to duplicate the noise by moving the follower on the fuel pump eccentric back and forth (for and aft) quite a bit. I don't remember the follower having so much travel. I'm able to move it back and forth more than an eighth of an inch. It seems excessive, but I don't have anything to compare it to. Any opinions?

Thanks!

Chuck


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## geeteeohguy (Feb 2, 2008)

Yeah...go to the auto parts store, ask for a fuel pump, pull it out of the box to compare it to yours, and wiggle the arm and see if it too is loose. If not, buy the new pump...


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## chuckha62 (Apr 5, 2010)

The pump arm is nice and tight. It's the follower itself (the ring that rotates around the eccentric). I just ordered a complete eccentric assembly from Ames.

(I call it a "follower", but maybe that's not the best term...)


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## chuckha62 (Apr 5, 2010)

*Resolved!*

Good news... The rattle was the fuel pump eccentric and "follower". They were just too loose. I couldn't find a new one here locally and it took a week to get parts from Ames, but after the wait, the noise is gone!

Additionally, I feel much better about the water pump being properly clearanced. I know it's a bit premature, but driving around today, it seems that the temp doesn't rise as quickly when sitting and idling for a long period of time. My only area of continued concern is the front cover housing. the rail where the water pump seals is/was corroded and seems pretty thin. I'm concerned about a water leak, but I'll address that if/when it happens. 

Does any body know where I can find a '67 front cover? It appears the aftermarket cover/housing being made is the newer style for the 11 bolt water pump.

Cheers all!

Chuck


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## geeteeohguy (Feb 2, 2008)

Chuck, you can build up that rail and fill any pitting with JB weld. Then, paint the whole inside of the cover and divider plates with Glyptal to keep any future electrolysis from occuring. 8 bolt covers are out there, usually for about $100-$150. Try the Performance Years forums.


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## chuckha62 (Apr 5, 2010)

geeteeohguy said:


> Chuck, you can build up that rail and fill any pitting with JB weld. Then, paint the whole inside of the cover and divider plates with Glyptal to keep any future electrolysis from occuring. 8 bolt covers are out there, usually for about $100-$150. Try the Performance Years forums.


That's what I've been thinking... I'm sort of keeping JB Weld in my back pocket (so to speak). I hadn't thought of Glyptol, that's a good idea! Thanks!


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## BearGFR (Aug 25, 2008)

Awesome. I had the one in the Beast back out to the point where the fuel pump quit working. Jim pointed out to me that's a 1/2" bolt - you don't have to be gentle with the torque wrench. That sucker ain't coming off again.... 

My problem was that I hadn't gotten the eccentric keeper perfectly centered over the nose of the cam (it sticks out beyond the front of the timing gear a few thousandths when it's right).

Bear


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