farmall 350u no power - valves?

JeffL · Nov 14, 2016

new post related to old post "Farmall 350 valve noise??"

wondering what to check to confirm suspicion that i need a valve job (before i tear my tractor apart.)

after a little more use (since a noise started that I guess comes from valves) tractor can not even make it up a medium grade hill on it's own.

when sitting fairly level, just raising bucket up and down causes it to almost die.

it will rev up to pretty normal RPM, just seems to lack power.

also seems like more flames than usual come out exhaust.

Charlie M · Nov 14, 2016

A compression test will tell you if the valves are bad. Have you checked to see if they have the right clearance. Pull the valve cover and see if everything is working correctly. Points that are going bad
make my tractors loose power or not start at all.Has the tractor been running OK or is this sudden. Does it sound OK when not under load.Maybe something in carb not letting it get extra gas under load. Valv e
jobs aren't cheap so if it were my tractor I would check out a lot of free stuff before spending money on valves.

Janicholson · Nov 14, 2016

A cam gear with a loose or wallowed out Key can make those symptoms. The Utility is a frameless design. This means that
you need to check cam timing next to assure that the diagnosis is correct. I would do this by rotating the engine clockwise
with the hand crank, or jacking one rear wheel an with it in 5th gear and TA forward, push on the top of the lifted wheel
forward until the #1 cylinder is a little past the point where that valve is closing. Now mark the pulley at the timing
mark. and carefully move the engine backwards and watch that intake valve (or measure its height before turning backwards,
and keep measuring as you turn backwards). There should be less than 1/16" movement of the pully in relation to your mark
before the valve starts moving. What you are looking for is slack in the drive of the cam. If it has noticeable slack, the
cam drive gear is loose on the cam. It means removing the front bolster and pulling the front cover to fix it. Jim

Brownie450 · Nov 15, 2016

Easiest things first.

Check points/ condenser---gap points at .020---check timing
Check spark plugs
As Charlie said-compression test to see how tight valves/ rings are
Check valve lash--adjust when hot. Get correct gap figure. Usually .017 hot
Check for air leaking at intake manifold---gaskets
Jim

JeffL · Nov 15, 2016

when the problem initially began the tractor had been running very well for around four hours of pretty hard work then fairly sudden loss of power plus upper engine noise.

I did check the ignition timing, point gap and plugs several times.

will check for loose cam gear and try compression test in the next couple days.

it sounds even stranger now when it runs, i'll try to post a recording or something.

i don't know how to check for manifold leak

Brownie450 · Nov 15, 2016

Might try pulling 1 plug wire at a time out of the
dist. cap & see if that has any effect on the noise.

Believe I'd pull the valve cover & see what's going
on in there. You could have push rod/ rocker arm
trouble. You'll be able to get an idea if it's maybe
a valve thing.
Jim

JeffL · Nov 15, 2016

I had tried pulling one plug at a time while it was running. I didn't notice change in the noise much. I did notice that I got zapped just touching one of the wires. Is that something I should be concerned about?

The wires are reasonably new but are Tisco kinda cheap.

I worked a bunch with it running with the valve cover off and none of the valves seemed to feel much different than any other with my finger on top.

Janicholson · Nov 15, 2016

Sudden onset power loss with knocking like noise is usually not spark or fuel. Another idea on the cam drive hub failure is to turn it slowly and look for the valve train to make
sudden snapping moves either forward or backward as it is turned by hand (plugs out with the fan belt!) Jim

300 dave · Nov 16, 2016

my 350u had similar symptoms, had to change plugs every day or sooner. it was on a backhoe so I could live with it. Winter I pulled it to find timing gear and key badly wallowed out as janicolson has stated good luck

David G · Nov 16, 2016

Have you checked the ignition timing?

Brownie450 · Nov 17, 2016

If the valve train appears to be in good shape, upper engine noise would
possibly be piston slap or connecting rod getting loose at the piston.

Compression test would give an idea of what might be going on.
Jim

JeffL · Nov 19, 2016

Lots of feedback.

Took out plugs and turned engine normal until middle timing mark lined up and #1 valve was moving. Put my depth gauge on valve spring and moved engine backwards until valve moved a couple thousandths according to depth gauge and the pointer was hardly moved. Did it a couple times. Also watched with eyes on several other valves moving engine forward and back and can't seem to see or feel much play.

Ran it with valve cover off and plugs out and no fuel with the starter a bunch and nothing notable in noise or movement that seemed odd.

Got it to run good enough to make it up the incline. If I retard the ignition timing the noise gets worse but engine power gets better. If I retard the ignition timing the noise all but disappears but power is awful.

While doing all this the engine side cover on the manifold side started to squirt out antifreeze. I think it is a hole in the cover itself.

I will try to post a video shortly.

JeffL · Nov 19, 2016

Here is a video. For the record it wasn't me who painted it yellow

JeffL · Nov 20, 2016

Took out plugs and turned engine normal until middle timing mark lined up and #1 valve was moving. Put my depth gauge on valve spring and moved engine backwards until valve moved a couple thousandths according to depth gauge and the pointer was hardly moved. Did it a couple times. Also watched with eyes on several other valves moving engine forward and back and can't seem to see or feel much play.

Ran it with valve cover off and plugs out and no fuel with the starter a bunch and nothing notable in noise or movement that seemed odd.

Got it to run good enough to make it up the incline. If I advance the ignition timing the noise gets worse but engine power gets better. If I retard the ignition timing the noise all but disappears but power is awful.

While doing all this the engine side cover on the manifold side started to squirt out antifreeze. I think it is a hole in the cover itself.

here is a link to a video:

https://youtu.be/Idf0vfYrHxs

Tom Dowling · Nov 20, 2016

I watched and heard the video, it's valves tapping that I heard. Here's an old trick to pinpoint which one... get a large screw
driver, the longer the better, touch it to the rockers one at a time when idling while holding your ear to the handle. You'll
hear a lot of noise and can track the loud tap to the source.

Tom Dowling · Nov 20, 2016

You can also put the screwdriver on the block to listen for other stuff.

JeffL · Nov 20, 2016

once I locate which valve is making the noise then what do i do to fix it?

also the hole I mentioned in the engine block side cover - i am afraid it might be made from a broken part on the inside

am i basically looking at a pretty major tear-down?

300 dave · Nov 20, 2016

If you push the handle hard against your skull just in front of your ear it works well. Do not put the point on any moving parts. Don't ask me how I know this is a bad idea. HF sell a stethoscope and they seem to work.

Tom Dowling · Nov 20, 2016

The leaking cover is rusted thru, new are available or maybe it can be patched. There's nothing to break under the cover on the
carb side of the tractor. As for the valves, once you've isolated the noise check the rocker where it contacts the valve stem,
you may have a ridge worn in the rocker giving you a false read on your feeler gauge. Do you have good oil flow when it's
running with cover off? Rocker or the shaft may have worn groove also.

JeffL · Nov 27, 2016

The engine just blew a giant hole in the side just under the cover with the small hole in it. I see a rod broken in the hole. Strange that it had OK oil pressure and temperature and I was only moving it at fairly low RPM. I guess I'll start a new post about engine swap.

farmall 350u no power - valves?

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