Strange Engine Noise

B

bdtutton

Senior Member
Hello,
I have only owned my 1930 Ford Model A Tudor since last fall when I purchased it from a local classic automobile dealer. I drive it to work on any sunny day that is not too cold because it does not have a heater. It is 25 MPH for the first mile and the last mile of the 9 mile trip. I usually reach a maximum of about 50MPH for about 2 miles in the middle of the trip. I run 10-30 Mobile 1 synthetic oil and change it every 500 miles. It has had a couple of 10 mile trips at 45-50, but I try not to exceed 50 because deer and other cars become a test of tires and brakes.

I was driving the other day and as the engine was coming down to an idle at a stop there was a funny rattle sound at about 750 RPM (my guess). It sounded like a loose piece of sheet metal so I did not think much of it. The next day it happened a couple of times and I started searching for the rattle. At first I thought it was within the bell housing, but it seems to be near the rear of the engine. The confusing part is the sound only happens around 750 RPM, it sounds like sheet metal rattling and it doesn't make much noise until the engine warms up a bit. I tried shorting a few plugs to see if the noise would stop...and it did on all cylinders because the engine would slow and be in the quiet RPM zone.

Oil pressure is 10-15 cold and about 2-3 PSI when warm. Engine is starting and running fine, but I would like to fix this before any damage is done if possible.

I am new at this and I know some of you have been doing it forever so I hope I described things well enough to come up with some ideas.

Thank you....
 
I had the passenger door retainer bouncing around and I thought it was an engine noise. I could see it because I haven't built the interior kick panel yet. Not that thats going to be your problem. But you should check exhaust mounts and fasteners and linkages and all the stuff that could come loose and rattle like the floor boards and door handles. If the rattle matches rpm rise then you have to pull the pan and see if you can save it or rebuild it.
 
First, I think the engine oil your running is to thin, but has nothing to do with your question.

Second, Model A’ are known to make all kinds of different sounds that come and go. Cars are 90 years old.

Third, I would think your problem is something like a loose engine side pan, get car up in the air and check everything out. I think you have something loose.

We just had our Volvo XC70 serviced, part of the service was a 55 point inspection of the car.

Harmonic vibrations, I think you have one that is setting up around 750 RPM’s.
 
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i have a 36 Ford pickup with a 21 stud flathead, i had a rattle, it was only when i come to a stop. it was a worn out bendex there are little springs in it that where gone the gear was coming in contact with the flywheal
 
Good morning...Just a word of caution regarding speed in your 'new' Model A. Most Model A's came with 3:78 rear end gears and like to run at 40 mph or so. If you have the 3:54 or 3:27 rear end gears, then you can run faster on flat ground. I wish you many happy miles with your Model A...treat her gently, like your best girl...Ernie
 
Check to see how tight you radiator support rod nuts are, I had a noise like you have and i tighten them up and all is good.
 
The clutch housing has sheet metal covers on the upper opening and the lower opening. If it sounds like sheet metal, it probably is.
 
i'f you have the splash pans between the oil pan and the frame you might want to check them first, very possible that's where your noise is coming from
Tinkirk/Terry






bdtutton said:
Hello,

I have only owned my 1930 Ford Model A Tudor since last fall when I purchased it from a local classic automobile dealer. I drive it to work on any sunny day that is not too cold because it does not have a heater. It is 25 MPH for the first mile and the last mile of the 9 mile trip. I usually reach a maximum of about 50MPH for about 2 miles in the middle of the trip. I run 10-30 Mobile 1 synthetic oil and change it every 500 miles. It has had a couple of 10 mile trips at 45-50, but I try not to exceed 50 because deer and other cars become a test of tires and brakes.

I was driving the other day and as the engine was coming down to an idle at a stop there was a funny rattle sound at about 750 RPM (my guess). It sounded like a loose piece of sheet metal so I did not think much of it. The next day it happened a couple of times and I started searching for the rattle. At first I thought it was within the bell housing, but it seems to be near the rear of the engine. The confusing part is the sound only happens around 750 RPM, it sounds like sheet metal rattling and it doesn't make much noise until the engine warms up a bit. I tried shorting a few plugs to see if the noise would stop...and it did on all cylinders because the engine would slow and be in the quiet RPM zone.

Oil pressure is 10-15 cold and about 2-3 PSI when warm. Engine is starting and running fine, but I would like to fix this before any damage is done if possible.

I am new at this and I know some of you have been doing it forever so I hope I described things well enough to come up with some ideas.

Thank you....
Click to expand...
 
I had a rattle at powering down, almost bell type. Turns out it is a loose baffle in the exhaust muffler. I aint pulling it apart yet, just live with it.
 
I found my automotive stethoscope and went looking for the mystery sound that made me think something major was about to come apart. It took a while, but I found a loose nut that allowed the engine vibration to create the mystery noise that made me think I had a serious problem. I actually found several minor noises that were fixable. It is amazing how much quieter my car is at idle and going down the road.

I have learned a few key things from this forum over the last few months.....
1. Most carburator problems are electrical
2. Just when you think your engine is going bad, you find something that has shaken loose that is about to fall off the car rattling away.
3. Anytime you think about going over 50 mph you have to think about stopping.

Thank you everyone....
 
I had the same noise on my 30 town sedan. Drove me crazy while on a tour with my club. Every so often out checking and listening. Got home and slide under with the car running and a friend running the engine up and down in rpm.
Took a little while but found the wierd tinny noise .I Had engine pans and a couple of the bolts had broken the pans in a ring right around the bolts holding them to engine.had to look close to see , but after reving engine and as rpm came down you could see the pans vibrating around the bolts
 
I've had some very surprising rattles through the years. The trickiest one was only at certain RPMs and sounded like it was under the car, or on the firewall.

I spent a lot of time walking around the car and banging on every panel I could think of trying to force it to rattle. It turned out that one of the wings on the top of the radiator, the ones that the hood rods bolt to, had broken off of the radiator. The rod would vibrate and transfer the sound to the firewall.

Keep banging on panels, brake rods, running boards, etc. trying to force it to rattle. You will find it.

Ken
 
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