Diagnose by Sound?

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Sjschmidtky
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Diagnose by Sound?

Post by Sjschmidtky » Tue Jun 04, 2019 4:37 pm

Novice here....

Can a problem be diagnosed by listening? I've just started by 1923 T for the first time this season (yes, I'm late). Quite a bit of sputtering from the exhaust and some roughness in the engine. I took a short video (https://1drv.ms/v/s!AoOCcCJSc1JliJYohPZ ... Q?e=yJeqbb). Any suggestions based on the sounds?

Thanks, Steve


Peter, Memphis TN
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Re: Diagnose by Sound?

Post by Peter, Memphis TN » Tue Jun 04, 2019 5:33 pm

Could be an exhaust valve sticking open.

To check - take all 4 plugs out. While someone slowly turns the crank, use a flashlight and look into each cylinder and watch the valves move up & down. You can tell the intake valves from the exhaust valves by their positions - next to where the affected manifold attaches.

If you suspect a valve stuck open, you can remove the cover plates on the side of the engine, and do the same test, which will tell you whether everything is working, and if not, whether it's the valve of the tappet that is stuck. It's a bit harder to see in there, which is why I suggested the other first.

BTW, while the plugs are out, you might do a compression test. All 4 cylinders should have about the same pressure, somewhere around 30 - 40 lbs. If one is much lower, or zero, you'll know that is where the problem is.

If you find a valve stuck open, you might try dribbling some penetrating oil through a small tube like a WD40 can uses, down alongside the valve. Then use a wooden dowel to tap it down, and turn the crank to raise it up, and repeat a few times in hopes that the oil will free up the sticking. Worth a try!


Scott_Conger
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Re: Diagnose by Sound?

Post by Scott_Conger » Tue Jun 04, 2019 5:48 pm

Hold each coil down one at a time and find the cylinder(s) that are not firing or are mis-firing.

Pull the plug from the offending cylinder(s)

You can see both valves with a flashlight and determination

then:
If you find a valve stuck open, you might try dribbling some penetrating oil through a small tube like a WD40 can uses, down alongside the valve. Then use a wooden dowel to tap it down, and turn the crank to raise it up, and repeat a few times in hopes that the oil will free up the sticking.
Peter's advice here is the right thing to do and I'll bet your trouble will clear up without too terribly much effort
Scott Conger

Full Flow Float Valves - deliver fuel like Henry intended!


Topic author
Sjschmidtky
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First Name: Steve
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Location: Villa Hills, KY, USA

Re: Diagnose by Sound?

Post by Sjschmidtky » Tue Jun 04, 2019 6:15 pm

Thanks so much! I’ll try as you suggest.

Btw, I think I should buy a compression tester anyway. Would any work (e.g., cheap one from Harbor Freight)? I’ve not used one before. I assume you attach it to the spark plug hole, crank the engine and what it reads, right?

Steve

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Mark Gregush
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Re: Diagnose by Sound?

Post by Mark Gregush » Tue Jun 04, 2019 7:11 pm

Yes that is about it for doing compression test. You can open the throttle but on these engines does not change reading is left closed. Take all the plugs out and leave key off. If you get one from HF make sure it only reads 0-200 pounds or less.
You will need a 14MM to 1/2" pipe thread adapter. https://www.modeltford.com/item/5201CAD.aspx
This is not an off the shelf item. Not knowing what tools you have at hand, but you could make your own but you would need the correct drill(letter size), 14MM tap and brass 1/2" NPT brass pipe reducer.
I know the voices aren't real but damn they have some good ideas! :roll:

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Peter, Memphis TN
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Re: Diagnose by Sound?

Post by Peter, Memphis TN » Tue Jun 04, 2019 8:16 pm

My compression tester has a rubber 'nose' on it, that you just jam down into the spark plug hole. The only problem is, you need both hands to hold it down tight, and that means you need someone else to hit the starter.

Generally, you should crank the engine enough for the cylinder you're testing to go through 2 or 3 compression strokes. That will give you a more accurate reading than just one.


Scott_Conger
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Re: Diagnose by Sound?

Post by Scott_Conger » Tue Jun 04, 2019 9:05 pm

IF you buy the compression tester, what do you intend to do with the results? Unless you're prepared to remedy a low cylinder, ie., pull the head pull the valves, do a valve job and maybe even pull the pistons and hone the cylinders and put in new rings, I wouldn't bother. Whatever developed over winter is not broken or worn out from sitting. It will soon be running as well or poorly as it did when put into storage.

Too many times I've heard someone who was perfectly happy with their T and how it ran, do a compression test, and subsequently lay awake at night worrying about 1 low cylinder reading. There is no point doing this to yourself.

Now, for full disclosure, I own a dedicated "T" compression gauge, and use it. But I use it when I do NOT know a thing about the car and it is running poorly, and the owner has told me he wants it FIXED. This is not your situation.
Scott Conger

Full Flow Float Valves - deliver fuel like Henry intended!

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Steve Jelf
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Re: Diagnose by Sound?

Post by Steve Jelf » Wed Jun 05, 2019 12:01 am

The problem with modern compression testers is that they're for modern high-compression engines. A scale that goes up to 300 psi may not be terribly useful for a Model T, especially if it starts at 50 as some do.
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