Ford model a knock

[Dtolson9]

My 4 banger developed a loud knock today. Can anyone give me pointers on where I should start to fix my problem?

[Utopia Texas]

Can you give more facts to help determine where the knock is generated? How many miles on the engine? What was going on when the knock started? At idle, acceleration or all the time? Could be a myriad of things from main bearings, rod bearings, wrist pins, piston slap, crankshaft lateral play, crank to cam gear play, cam tensioner spring etc. start by giving some facts and then the group can give you some educated guesses.

[BILL WILLIAMSON]

If you suspect the center main, short out #2 & #3 at the same time & it'll be quiet.
Bill W.

[burner31]

Have you checked your oil?
Level/smell/color

[Dtolson9]

Miles of the engine are unknown. The car was sitting there idling and I accelerated a little and the knock started up and is there at idle and acceleration. If you email me I have a video of it running so you can hear what I'm talking about. [email protected]
I have checked the oil and it looks like oil and doesn't have any strange smells and is where it's supposed to be

[Tiny]

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Originally Posted by Dtolson9

Miles of the engine are unknown. The car was sitting there idling and I accelerated a little and the knock started up and is there at idle and acceleration. If you email me I have a video of it running so you can hear what I'm talking about. [email protected]
I have checked the oil and it looks like oil and doesn't have any strange smells and is where it's supposed to be

I sent you an email

[tbirdtbird]

post the vid on youtube

[Tiny]

Disclaimer: I haven't watched them yet just helping out David

Click on the thumbnails for the video

[Tiny]

I don't what it is but it sounds similar to a friends engine that a wrist pin got loose in and scored the cylinder really bad. Time to pull the head and oil pan and start investigating. I wouldn't be running it anymore until I opened it up

[Dtolson9]

Anyone have any ideas?

[700rpm]

It doesn't sound like a main in the videos, at least to me. I'd check wrist pins and rod bearings first, since that is one step to the mains.

[tbirdtbird]

would not load for me
takes me to photobucket then nothing happens, just blank screen

[Dtolson9]

Anyone think it could possibly be the oil pump?

[Brian T]

As it started knocking suddenly after reving the engine, but was OK yesterday I would think it was most likely the timing gear coming apart.

[Dtolson9]

In the videos posted there is a video of it running and not knocking and a couple minutes later it started knocking

[Tom Wesenberg]

Originally Posted by tbirdtbird

would not load for me
takes me to photobucket then nothing happens, just blank screen

The same thing for me.

[Dtolson9]

This was the first time I have ran the motor for more than 5 minutes since I got and I have no clue how many years it's been sitting

[Dtolson9]

Email me tom and tbirdtbird and I can send you guys the video. [email protected]

[WestCoast]

check and see if the crank pulley is loose , it can cause knock like a bad main bearing

[CT Jack]

Before pulling the pan try doing the timing gear test. Remove the timing pin on the front of the engine. Find a 1/4" or 3/8" wood dowel approx. 1-1/2" - 2" long. It should be long enough to hold with your fingers. Start the engine and slowly insert the dowel in the timing pin hole until it makes contact with the turning timing gear. Lightly push on the pin and listen to the knock. If the knock goes away or gets softer as you push the dowel your problem is a worn timing gear. This is a fairly simple repair to make.

[tbirdtbird]

have not seen/heard vids
1. do what Bill said #3
2. then short out one plug at a time to see if anything changes
3. knock only at idle? Only on accel? only on decel? Please clarify
report back

when u short out a plug you take a long screwdriver and hold it between the top of the plug or the strap and the cyl head

[Tiny]

Originally Posted by Tom Wesenberg

The same thing for me.

That's weird. It works on my iPhone, iPad and my pc. Did you press the play button?

[tbirdtbird]

LOL of course we did. The screen was totally blank

[Tiny]

The knock is pronounced enough that I would not start that motor again. A gasket set is cheap I'd open it up

[40 Deluxe]

Another timing gear test: Remove spark plugs and slowly turn engine over with the hand crank. If the gears are worn, there will be a distinct clack as the valve springs push the cam ahead of the crank (two valves at a time open, putting a load on the gears. Then two other valves close, and the springs pushing on the lobes push the cam ahead of the crank='clank'!)

[James Rogers]

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Bad main bearing. You can hope for something simple but, it is going to be a rebuild.

[Neil Mylar LakewoodCA]

All good suggestions.
I wish I had those suggestion back when I owned my first Model A.
The engine developed a rather large knock.
I never did figure out where the knock was coming from, but I finally had to replace the engine because it was using too much oil.

Neil

[BILL WILLIAMSON]

Tolson,
If you happen to have the starter off, see if the flywheel will rotate back & forth 1/8" or so. If so, the flywheel bolts are loose. This is a fairly common problem.
Bill Tight

[Dtolson9]

I will be trying all these things Saturday and I will report back with my finding. Thank you all

[Dtolson9]

Found the problem. Cylinder 4 piston is in pieces in the oil pan.

[700rpm]

Originally Posted by Dtolson9

Found the problem. Cylinder 4 piston is in pieces in the oil pan.

Yeah, that'll do it!

[Mitch//pa]

Did you also have a miss and or possible excessive blowby due to that piston?

[Tom Wesenberg]

Any idea what caused it?

[Dtolson9]

It would studder a little at first and be completely fine after. Didn't smoke or anything just sounded awful. No clue what caused it. I'm assuming at one point the motor was stuck and a previous owner hit the top of it with a hammer since it gouges in it. The cylinder had no scrapes or anything in them

[700rpm]

Originally Posted by Mitch//pa

Did you also have a miss and or possible excessive blowby due to that piston?

At my age, Mitch, all I get from a miss nowadays is excessive blowby.

[marc silva]

A friend of mine had a couple slightly loose flywheel bolts and you would swear it was a rod.

[Dtolson9]

Here's pics

[Dtolson9]

Anither

[goodoldvic]

Wow that sucks, looks like there was some detonation going on in that hole. Whats your next step?

[burner31]

Yuk

[Dtolson9]

I've been told by the local model a guys I can just drop a replacement in since the cylinder isn't scored at all.

[Bob C]

The new piston will need to weight the same as the old one.

Bob

[Dtolson9]

That's what I'm told. I need to measure this one and see what the bore is as well

[chap52]

Good news that the cylinder was not damaged. Just went through a piston issue with my V8 and went ahead and replaced all the pistons. Figured I would rather do it now while I am still young enough to (70) crawl under the truck. More importantly, get back out from under the truck.
Keep us posted.

[Dtolson9]

Thanks for the input guys. It's all back together and on the road.

[slackcat]

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Good to hear.

[mshmodela]

Nice to read... Great job!

[chrisabes]

This thread is perfect timing for me with great information. I too have an engine with a bad knock. Pulled it out today to investigate. A couple of members of the local Model A Club have suggested it could be a loose flywheel, as mentioned in a couple of earlier posts. Will know when I pull it apart in the next couple of days.

[Special Coupe Frank]

I'm a little late to the party, but I will chime-in for checking the cam-gear, and the plunger & spring...

My '28 had a knock at idle that sounded very much like a rod-knock... I tried the timing-pin / pressure trick, and it subsided/ disappeared.

Took the side-cover off the timimg area, and let the engine idle: cam gear/shaft was "walking" fore & aft, making a knocking sound. (Do NOT rev the engine with the side-cover removed: your fender will be covered in oil! )

THIS was my "bearing knock"... when I disassembled the front cover, I found the plunger flush at the top of its bore, and the spring in about 3 pieces... it was doing no good.

When I replaced the plunger and spring, and put it all back together, the "rod knock" was gone.

It's an easy thing to check...

Obviously, your case was different ... good thing you shut it down before the cylinder was damaged !

Good luck !

Frank

[john in illinois]

I am late to the party also,but here is good motor noise information. Glad you fixed the piston.

http://www.foxvalleymarc.com/Tech_se...ne_noises.html

John