ConcoursMustang Forums
1st Generation 1964 1/2 - 1973 - Questions & general discussions that apply to a specific year => 1966 Mustang => Topic started by: rrenz on February 02, 2017, 07:59:43 PM
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Ive owned my 66 c code coupe for just about two years now. The motor has always had a slight "knock" to it. Im fairly certain the current motor was donated from a 65 so I'm not sure what was done to it. At the time I was fairly certain that the noise I was hearing was the water pump. The car had headers and a dual exhaust at the time so narrowing down sounds was rather tricky. During the first winter I started to return the car to its stock appearance starting in the engine bay. I stripped down as much as I could and repainted the block. During this I determined that the water pump was not my issue. I put a new fuel pump,alternator and starter in. Rebuilt the carb and got everything back into spec. With all that being said the new stock exhaust is on the car and the "knock" is now more audible. The car Idles, accelerates and cruises absolutely beautifully. The sound is intermittent. sometimes its quite loud usually after a long drive or during a cold start. Other times there is no knock at all. Ive exhausted every type of troubleshooting method I could find. I changed the oil this past weekend and found no metallic residue or any kind of grit in the oil.With a stethoscope I've probed every inch of the block. Down low you can hear smooth running gear. At the valve covers you can hear the valves ticking away. Only one cylinder is a tad bit louder than others as far as lifter noise goes. So with all that being said the fuel pump seems to be quite loud. Almost anywhere I probe with the stethoscope you can hear the fuel pump tick away. Ive heard of the fuel pumps causing a "Knock" sound. Ive also heard of other people having this same sound. Ive also heard a similar knock on other 289's. My question would be is this considered a "normal" small block ford sound? or has anyone else encountered this?
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Just a place to start
Is the "speed" of the knock the same as the crankshaft or more than (double) the rotation of the crankshaft?
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One thing i noticed is that if not in unison with the fuel pump tick its about the same speed so I would say its half the speed of the crank.
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Engine noises are difficult to pin down when heard in person. A written discussion about possibilities can produce multiple rabbit trails. If you think it is a fuel pump, by pass the pump and remove it from the engine, you can run the engine with a cover or open temporarily (will leak a small amount of oil) but it will prove or disprove the fuel pump theory.
My vote is on piston slap. (Cylinder bore larger than piston or skirts of piston worn down)
Truthfully, talking about it will not fix it. I've heard many engine noises over the years of turning wrenches for a living and I can identify most by ear but there is always a new one somewhere that just baffles even the trained ear. Sometimes the only way is to take the engine down and explore.
About 20 years ago on my 289, I had a "misery knock", louder on warmer days as the engine warmed, even louder at times the more I gave it gas too. I had never heard this knock before in all of my years of professional wrenching and engine building. It was a "new" kind to me. When I took the engine apart exploring, I didn't really find anything at all. Even the cylinder walls still had the factory honing marks very visible. The camshaft bearings looked bad though so I assumed that was the mystery noise but it didn't look like what I heard. I had new cam bearings put in and the cylinder bores mic'd out, the bores were within specs. I began pulling the old rings from the pistons (while waiting on the rest of the block work) and one of the ring lands fell off with the removal of the rings. (The grove between the rings) I was shocked! I only needed a piston! More shocking was it didn't hurt the cylinder wall!
My example was unusual, but it is REAL. The cause: Low octane detonation. Hind site now 20/20, I did notice the destination pings in the center of all the pistons. Running Regular pump gas during the 1990's the cause. I guess the "Premium Fuel" decal isn't just a sticker!
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Long ago I had similar situation that turned out to be fuel pump. The sound was "once around" and same frequency as cam or half crank speed. I imagine if the fuel pump lever leaves the lobe of the eccentric on the low side there will be a knock as recontact is made.
Swapping fuel pumps cured my problem.
Kurt.
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Long ago I had similar situation that turned out to be fuel pump. The sound was "once around" and same frequency as cam or half crank speed. I imagine if the fuel pump lever leaves the lobe of the eccentric on the low side there will be a knock as recontact is made.
Swapping fuel pumps cured my problem.
Kurt.
I have experienced this with a brand new parts store fuel pump. Installed a Ballard original and the noise was gone.
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+1 on swapping the fuel pump. Not too expensive of a test for piece of mind. I had a "tick" from my 289 fastback that was faint if at all at idle but louder when you would accelerate. I ended up rebuilding the carb, readjusting valves, replacing the tri-y's (possible pin hole), replaced the exhaust gaskets twice,etc. I thought it was mechanical at first but then leaned more towards exhaust, but could never find it, though it did seem to be more pronounced on the passenger side. One day I was wiping near the pass. exhaust header while the car was idling and while leaving the papertowel there, noticed black dots ??? My hunch was a "leak" coming from between the head and engine block. NOT common from what I have heard. Low and behold I removed the heads to have them rebuilt (for piece of mind, although they only had roughly 50,000 miles on them) and found that there was a "leak" created in the head gasket between the 3rd piston laterally to the outside of the block. These were good quality Fel Pro gaskets too, which I have never had issues with. So the $20 head gasket ended up costing me over $1000 not including my time (and pain and suffering) ;D
Hopefully you will get lucky with the fuel pump. Best of luck
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Thanks to everyone for the suggestions. During startup this morning the noise was a bit loud so i got my stethoscope out again. Obviously it was notable when contacting the fuel pump so i moved around the block. The only place i could really hear it resonating was above the pump at the timing chain cover. Shortly after the noise subsided i could no longer hear it at the cover but only on the pump. Im still suspicious of the pump at this point.
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rrenz;
I purchased a 66 Mustang in 1989, and it had a similar noise to what you are describing. The engine had great oil pressure, did not overheat, and the noise was fairly consistent. If I recall correctly, I read a TSB that described the camshaft being able to move forward and backward, and it was described in the TSB as a "chucking noise". Maybe Jeff can chime in with more on this?
I sold the car to a local gentleman, disclosed the noise to him, and it's probable cause and to this day, he drives the car in the summer, and it still makes that noise!
Hope this helps.
Ken
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Engine tolerances of the 60's (and before, and a couple of decades after) were not as tight as today. That resulted in noise. There's another factor, the oil. Back then, a 30 weight oil was about as thin an engine oil that was recommended for cars. Then came STP, ask Andy Granatelli. Try a thicker oil. Just a thought.
Jim
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I had considered a thicker oil but wasn't sure what would be "safe" is anyone else using a thicker oil that could suggest a good weight? I am currently using 10-30 which is definitely like water.