Banging noise coming from the oil pan - 1973 351C original 4V engine......

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fordismyboss

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Yikes! I've got a noise coming from the oil pan on my all original low miles 1973 351c four bolt engine. I put the car on the lift and can hear it very well. No evidence of something hitting the pan, I'm thinking something could be hitting the baffle. Oil pressure is very good.

Anyone ever hear of something like this? I'm thinking I'd better pull the pan now, but I thought I might get some better guidance here first.....

 

Vicus

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To narrow down the possible error, your information is unfortunately not sufficient for me so far. The crystal ball remains cloudy.

I assume the noise is in sync with your engine speeds, right?

Since you still have good oil pressure, I'm ruling out a loose main bearing bracket or a loosened oil pick up. You won't get around removing the oil pan.

 

fordismyboss

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Yes, it is in-sync with RPM. Yes, good consistent oil pressure. What could possibly cause this? Dip stick? Baffle too close to the oil pick-up? 

And yes, I guess I must remove the pan. But if then I see nothing, I have not properly identified the noise or location. But, it would be best to find nothing!

 

Hey Jerry

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Hi, yes unfortunately off comes the pan. Obviously besides a visual inspection I would remove some rod caps and take a look. Yes, it would be best to find nothing but at this stage you want an answer. 

 

Hey Jerry

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One more item. Noise travels. If this is an automatic I would first check torque converter bolts. I could share lots of engine and transmission stories I fixed but then I would reveal my age. Old

 

boilermaster

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fordismyboss,

Hey jerry makes a good point about the  tc nuts, defenitely go there first.

I can only add that the oil pump pickup is threaded to the oil pump, it is remotely possible that it is not level with the bottom of the oil pan or worse yet loose by one complete thread.

When I have a pan off, I always check the bottom of the pickup with a level.

The only way that I can think of to check this would be to take like a hammer handle and press against the bottom of the pan (as it will give a little bit)

and see if the noise changes when pressure is applied or released.

You might be able to get a visual with the oil drained and a very good light or borescope. 

lastly, if the oil dipstick tube is not seized you could see if removing or rotating it has any bearing on your noise.

Hope this does not seem too far fetched, but when the obvious wont work, try something else.

Boilermaster

 

Don C

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+1 on sound (and vibrations) traveling. You'd be surprised on how often an engine knock turns out to be something external, such as loose fastener or tailpipe touching something.

 
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Hemikiller

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If this noise just started, then a best guess would be the rear portion of the baffle broke loose from a spotweld. 

 

fordismyboss

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If this noise just started, then a best guess would be the rear portion of the baffle broke loose from a spotweld. 
This is what I am hoping for, and nothing more. But I do need to make one more attempt to properly hunt down the origin location of the noise.

 
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This is what I am hoping for, and nothing more. But I do need to make one more attempt to properly hunt down the origin location of the noise.
 Do you have an automotive stethoscope? If not a log screwdriver use with the handle to the ear (of course!!) You'll hear all sorts of noises, but the problem noise should be loudest.

 

fordismyboss

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 Do you have an automotive stethoscope? If not a log screwdriver use with the handle to the ear (of course!!) You'll hear all sorts of noises, but the problem noise should be loudest.
Yes, I have a stethoscope. The target noise is a loud banging noise on the oil pan and a small ticking noise on the block.

 

fordismyboss

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Put the car back on the lift this afternoon. Using the stethoscope; SUPER LOUD BANGING on the oil pan below the 4 & 8 connecting rods. Pulled an original cobra jet oil pan I had on the shelf, and their is a low profile baffle under the rear 4 connecting rods. I'm guessing and hoping this is the culprit! The pan comes off tomorrow and I'll update with pics!

Thanks for your input!

 

fordismyboss

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Finally pulled the pan and found the rear counter balance nicking the end of the rear baffle. If Ford had made it .100" shorter it would have missed! But what a loud noise it made! The reason it hit was a previous owner jacked up the engine from the oil pan and crushed it about 1/2" at the front sump which broke a spot weld at the front baffle, and about 1/4" under the rear baffle which pushed the rear baffle up just enough to nick the crank counter balance.

Wonderful to see an original four bolt 351C Cobra Jet bottom end with serialized connecting rods in perfect condition. Wow!

So, now I need a new oil pan! Would like to find an NOS Cobra Jet pan or a perfect used pan.....anyone know where to start looking?

Thank you for reading! 

 

Sheriff41

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Whew!  Glad to hear it was not anything more serious.

 

Fabrice

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Whew indeed! Rare are those that lucky!
I thought that lifting a car using the steering rod and ofc bend it, as seen on my 71, was not that of a smart idea, but using the oil pan might get the crown! 

 

Hemikiller

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Finally pulled the pan and found the rear counter balance nicking the end of the rear baffle. If Ford had made it .100" shorter it would have missed! But what a loud noise it made! The reason it hit was a previous owner jacked up the engine from the oil pan and crushed it about 1/2" at the front sump which broke a spot weld at the front baffle, and about 1/4" under the rear baffle which pushed the rear baffle up just enough to nick the crank counter balance.

Wonderful to see an original four bolt 351C Cobra Jet bottom end with serialized connecting rods in perfect condition. Wow!

So, now I need a new oil pan! Would like to find an NOS Cobra Jet pan or a perfect used pan.....anyone know where to start looking?

Thank you for reading! 
Why don't you get it repaired. A good metalworker could likely do it quite easily. If you scrap it, send it to me and I'll fix it for my car!!

 

fordismyboss

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Boss 351, 38k miles, original with a few suspension improvements.
Why don't you get it repaired. A good metalworker could likely do it quite easily. If you scrap it, send it to me and I'll fix it for my car!!
Yes, I'm thinking about doing just that, but still also wanting a good pan if I can find one.

 
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