Knock when cold

[chris142]

My wife bought my 1957 Case 300 without my permission lol

About 8 years ago or so. It needed a lot of work but I got it going and use it to maintain my dirt road here in the mojave desert.

When started cold it has a nasty rap/ knock. Cold being anything below 100F.

Once warmed up to the 180° thermostat setting the noise is almost gone .

I'm thinking it's not a rod as that would get worse as the oil thins out as it heats up.

I have narrowed it down to #1 cyl but I don't think that matters.

All 4 cylinders work well. I can remove any 3 plug wires and it will continue to run on any 1 cylinder.

Am I on the right track?

BTW I have tried several oil viscosities and the best for quieting the noise is 20w50 . 15w40 was by far the loudest. Sae30 was in the middle.

Once warmed up I can rev it to full speed and use it all day. Just after a cold start does it sound like it's going to come apart .

Broken or somehow damaged piston skirt? Prolly laying in the bottom of the pan?

 

[Richard G.]

My wife bought my 1957 Case 300 without my permission lol

About 8 years ago or so. It needed a lot of work but I got it going and use it to maintain my dirt road here in the mojave desert.

When started cold it has a nasty rap/ knock. Cold being anything below 100F.

Once warmed up to the 180° thermostat setting the noise is almost gone .

I'm thinking it's not a rod as that would get worse as the oil thins out as it heats up.

I have narrowed it down to #1 cyl but I don't think that matters.

All 4 cylinders work well. I can remove any 3 plug wires and it will continue to run on any 1 cylinder.

Am I on the right track?

BTW I have tried several oil viscosities and the best for quieting the noise is 20w50 . 15w40 was by far the loudest. Sae30 was in the middle.

Once warmed up I can rev it to full speed and use it all day. Just after a cold start does it sound like it's going to come apart .

Broken or somehow damaged piston skirt? Prolly laying in the bottom of the pan?

First thing I would do is pull the valve cover and crank it and see if a valve is stuck when cold.
Also check adjustment on valves.
I have also seen lifters stuck when cold cause that.
Wife's straight 6 Jeep does that sometimes when cold.
Fixed a Toyota truck for a fellow years ago that did that.
It quit as I poured Marvel Mystery oil in it.

 

[chris142]

First thing I would do is pull the valve cover and crank it and see if a valve is stuck when cold.
Also check adjustment on valves.
I have also seen lifters stuck when cold cause that.

It runs too good for a stuck valve or lifter as that would cause a noticeable missfire. I adjusted the valves when I got it. All were real close to spec.

 

[Joe (Wa)]

Could be a lifter sticking beating the nose off the cam lobe, more likely a rod . You'll know for sure when the piston pin makes a big hole in the side of the block as it exits the engine. Not too uncommon in ship generator diesels running1800 rpm, especially the Clatterpiller diesels.

 

[Dingo3]

An exhaust manifold leak? Sometimes they quiet down a lot when warmed up.
Edit: Now that I think about it, the thicker oil wouldn’t quiet a leak…oh well.

 

[gmccool]

When cold try pulling one plug wire then putting it back on one at a time to see if the noise increases or decreases

 

[olddog]

Loose flywheel?

 

[CraigWis]

Maybe a Piston Pin or Piston Skirt. Both will get quit making noise when warmed up

 

[rustred]

My wife bought my 1957 Case 300 without my permission lol

About 8 years ago or so. It needed a lot of work but I got it going and use it to maintain my dirt road here in the mojave desert.

When started cold it has a nasty rap/ knock. Cold being anything below 100F.

Once warmed up to the 180° thermostat setting the noise is almost gone .

I'm thinking it's not a rod as that would get worse as the oil thins out as it heats up.

I have narrowed it down to #1 cyl but I don't think that matters.

All 4 cylinders work well. I can remove any 3 plug wires and it will continue to run on any 1 cylinder.

Am I on the right track?

BTW I have tried several oil viscosities and the best for quieting the noise is 20w50 . 15w40 was by far the loudest. Sae30 was in the middle.

Once warmed up I can rev it to full speed and use it all day. Just after a cold start does it sound like it's going to come apart .

Broken or somehow damaged piston skirt? Prolly laying in the bottom of the pan?

does it miss when this knocking is happening ? as it could be a sticking valve.

 

[Fritz Maurer]

If it changes with the different oils, then something is moving around in there that shouldn't be.

Cut the oil filter open and see if there's anything in it ( just to see if immediate tear-down is needed).

Some engines had a spring-loaded plunger at the end of the camshaft, in the timing cover, for thrust purposes. The helical cut of the gear can pull the cam one way , and any number of cam lobes under pressure in particular point of rotation can pull it back the other. As the cam heats up, it probably expands and takes up some of the slop.

Shorting out individual cylinders would probably not change the sound, like a loose rod would, since the cam is not subject to the combustion pressure.

Also need to determine if the sound you hear is at crankshaft speed or camshaft speed.

 

[chris142]

does it miss when this knocking is happening ? as it could be a sticking valve.

No. It runs well. I can remove any 3 plug wires and it will continue to run on just 1 cyl