Engine knocking

TDS

TDS

Member
Hi
I got a 1935 221 cui flathead with a strange knocking from front of engine.

It started on a drive some week ago.
After I replacded the carburator.
I thought it was a ignition issue and I therefore rebuild the whole ignition system including the distributor.
Sadly it didn’t solve the problem:confused:.

The Bendix drive on the starter motor was busted so I replaced the Bendix with a new one.
As it wasn’t the ignition I thought the starter drive could be the hitting the flywheel and cause the knocking.

It’s like at rhythm first a low knocking rhythm followed by no knocking and then followed by a louder knocking rhythm.

Its repeats and is there both at high idle and when driving but isn’t very noticeable inside the car when driving.

Exactly the same rhythm every time.

Engine is running steady without missing or backfire.

I have recorded a video see this link:
https://www.youtube.com/watch?v=Bhm1nGnpWn8&feature=youtu.be

I know it’s hard to say, but I would appreciate any good ideas - thanks:)
 
Last edited:
Hi Everyone, TDS, try uploading your video to YouTube, then post a link to the video here.

You don't say a lot about what you've done, but if I thought it was a bearing type issue I'd drain and carefully inspect the oil.

Reading again, I see you mention the front of the engine. Check all around the fan. Look for any cracks.
 
Last edited:
Hi Everyone, TDS, I'm totally not an engine expert. You will get some excellent advice. Tell us what you are doing, and what the results are.

I still think you can learn a lot by examining the oil. I have magnets that I've collected from computer hard drives that I put in the used oil drain pan, and carefully pour off the oil after it has settled for a day. Think like you are panning for gold!

Are you afraid to run it? The way it sounds I don't think I would take it onto the road.

If you are okay to run it, you can isolate a cylinder very easily using a very long screwdriver placed between the tip of the plug (where the plug wire connects) and the head (keep your fingers on the insulated handle!). This test can tell you if disabling a cylinder makes the noise go away. Try the test on all eight cylinders, with the engine at the slowest idle it will still run. Listen for the sound to change.

Good luck with whatever you find!
 
Since it started after replacing the carb there is the outside chance something fell into the intake and made its way into a cylinder. I had this happen once but was able shut the engine down (352 FE) quickly after the first start and pull the spark plugs. Using a borescope found a washer sitting on top of #3 piston and was able to fish it out with a telescoping magnet. Got away with that one. If this is what happened on yours, it sounds possibly whatever fell in is on the piston and hitting the cylinder head. This is a worst case scenario and hopefully it's something minor but I wouldn't drive it until you figure it out.
 
Thanks all
Will try to remove the belt tomorrow and the sparkplug trick. I will post the result.
Im 100% I didnt drop a bolt, nut or washer in the manifold.
Did it once In another car so I have learned my leason:-/
 
Here was the source of a strange sound in my 49 F1. The breather tube was loose and clanging around.
 

Attachments

  • IMG_20150725_160911639-1.jpg
    IMG_20150725_160911639-1.jpg
    52.5 KB · Views: 107
Quick and easy thing to do first.

As mensioned before, ground out each spark plug ( one at a time ), and listen
if the knock changes as you ground each. If the knock changes, then there is
a problem with that cylinder.






.



.
 
Try this, remove the belt, if the sound is still there take a stethescope or a long screw driver up to your ear, stick the end on the timing cover, the timing gear is a fiber gear and quite often they will wear out and have a lot of back lash, I had stock 35 years ago with a lot of miles on it, drove it for 2-3 weeks, wound it up one day and hit 2 gear, engine died, pull the dist cap off and rotor wasn't turning, stripped the timing gear. Walt
 
Hmmmm.....sounds like everyone has an opinion of what it could be, but a real professional mechanic should know and take the guess work out....just saying!
Find a qualified mechanic!
 
1938 Coupe said:
Hmmmm.....sounds like everyone has an opinion of what it could be, but a real professional mechanic should know and take the guess work out....just saying!
Find a qualified mechanic!
Click to expand...
===================================================




There are some of the most quallified flathead mechanics in the world
on this site, and some damn good back-yard mechanics here, too.

The information is free for the asking, and more times than not, the
advice given here helps the original poster with his problem. :p











.
 
I had a 39 coupe with a noise like that, it turned out to be the crank pulley rocking back and forth on the crank, the slot in the crank snout and in the pulley its self, they were wore pretty good, so was the pin
 
Gudgeon pin, pull one lead off at a time and see if the noise quietens to pinpoint which Gudgeon/ cylinder
 
Gudgeon pin = Wrist pin or little end. A mechanics stethescope or "listening stick" would help.

Mart.
 
If you listen to the vidio closly, every time there's a knock it goes retarded. I been
there with this one. Cam gear wiped out. Same noise on an F6 swear it was a
main. Sounds & knocks do travel - but my ears tell me the front and front main
bearing noise is rare usually the rear main. So after pulling the front cover sure
enough, fibre gear toasted. that was 40 yrs ago still running fine no noises.

this truck >>>>>>
 

Attachments

  • 20150204_163348_resized_1.jpg
    20150204_163348_resized_1.jpg
    31.4 KB · Views: 42
Hi
First, thanks all for your input.

I took the fan belt of.
Still knocking, so its not the pumps or the dynamo.
When I put my hand on the distributor I can feel the knocking.
Engine turned hot so I had to turn it of.
Pretty sure it not from any of the cylinders.

Will the engine run right if the timing gear is done?
The ignition timing is perfect and it starts immediatly.

Can the front camshaft bearing be causing a knockng like that?.

Im in to something I dont have much experience with :-/
 
TDS said:
Hi
First, thanks all for your input.

I took the fan belt of.
Still knocking, so its not the pumps or the dynamo.
When I put my hand on the distributor I can feel the knocking.
Engine turned hot so I had to turn it of.
Pretty sure it not from any of the cylinders.

Will the engine run right if the timing gear is done?
The ignition timing is perfect and it starts immediatly.

Can the front camshaft bearing be causing a knockng like that?.

Im in to something I dont have much experience with :-/
Click to expand...

I'd put my money on a bad cam gear, it's not the cam bearing, I wouldn't drive it very far with out checking that gear, it will leave dead in the road. Walt
 
You must log in or register to reply here.
Back
Top