641 engine noise

[46Chev]

I decided to repaint my tractor and tune it up. So now every small part is painted on my workbench icluding the the valve, side, and oil pan covers. While reading another post I became more concerned with a slight clicking noise towards the top of one of the rear 2 cylinders. I've checked what I can see and get at and everything is straight, tight. I thought maybe the push rods were supposed to be noisy. I really don't want to pop the head. If it is loose rod would it rattle on the crank? What's the best way to check it?

I guess I'm not sure what the "normal" sounds are supposed to be. But while its apart I'd like to address all that I can.

 

[souNdguy]

Try to pinpoint the noise. If you have a large brass drift or similar device.. place it to your ear and then tot he block.. it should help you get close to the area of the noise. You can also pull a plug wire on one of the cyls and see what change it makes on the noise...

list of 'bad' noises on these things is long.. everything from piston slap, to wrist pin, to valves clicking and ticking.. etc..

soundguy

 

[46Chev]

Well I'll have to put it back together and get it going again to pinpoint it. I only thought more of it since reading through some posts here lately. Pretty sure its the last cyliner (#1?) towards the steering and at the head. Thought (novice here!) there might be something obvious to see with things off; wear, metal flakes, obvious looseness, etc. The valve cover breather and oil filler breather both blow a little smoke. Is that normal or is that a sign of worn exaust valve guides?

What would be the best tolerance for valve lash with the engine cold? Should I knock off .005" due to variance in temp.?

 

[souNdguy]

No manuals with me to quote you specs..

Also.. #1 cyl is at radiator.

Some blowby out the breather is 'normal' wear on an old engine.. if it blows straight smoke.. i'd be doing a compression test to check rings and valves.

soundguy

 

[Anonymous-0]

Check the under side of the valve cover and see if there is any marks of contact( shinny mark).I had a tapping noise in the valve cover on my 641, it turned out to be the oil return line was loose and hitting the under side of the cover. Easy fix. Got a break this time, hope you do as well.

 

[Anonymous-0]

I favor a hardwood stick for this.A spark in the ear is not good.

 

[Anonymous-0]

something to transmit sound easily.its only on the head and block, no spark there.

 

[Anonymous-0]

can't you check the push rods with the side cover off.

 

[jimNCal]

I got a break on a 2000LCG last year with the same problem. It had a muted knock that scared off all the other prospective buyers. I was mostly interested in having the forklift mast on it and the Sherman Combo anyway so when I brought it home(cheap) and figured out the easy fix, I was pretty pleased.

 

[souNdguy]

I agree with bendee.. if you are getting a spark from the block, then the engine has other bigger problems..

soundguy

 

[GlenIdaho]

chev, the cold clearance is .014. They should be re-checked with the engine warm. In fact the manual calls for adjustment with a running engine after the initial adjustment. I did my 172 cold and checked it three times. When I ran it I found a couple that needed fine tuning. Hope this helps.

 

[Anonymous-0]

Just slip a little and land on a spark plug.Ouch.A model A ford with it bare plug connectors would convince any one who uses a metal bar.I use a stehescope now.I used a cardboard tube to find high voltage leaks in color Tv set.A brass drift wouldnt have worked well on that.A screw driver that extends all the way thru the handle can be much fun around ignitions.