Another 8N front pulley question

[Crinton]

Thanks Soundguy. Presumably you saw the videos, saw the pulley and heard the engine. Apart from exhaust noise (needs new muffler) there is a clunk, clunk, clunky knock, not sharp metalic but a knocking. To me, it sounds a bit like a big end knock when a fairly worn engine is under load but not on all four cylinders.

The engine has been worked on, probably about 15 years ago, a couple of years before I got it (it came with property). Oil pressure looks pretty good (see gauge) but it drops off when it gets hot, when I was last using it seriously a couple of years ago. I put in a new oil gauge about 4 years ago. Compression pressures in separate repeat tests (psi) are #1 - 105, 115; #2 - 105, 105; #3 - 106, 105; #4 - 55, 70, 75, + 2 squirts oil - 115. This was after running to get it warm but #4 may have dried out a bit but it certainly picked up with some oil added. Only added oil to #4. Sounds like ring problem on #4. Although there have been carb and ignition problem over time, tractor always starts right away even after sitting for months, with choke, but then has trouble picking up and running smoothly (fuel should now be OK; spark seems Ok but could it be variable - how to check?). All cylinder contribute, as indicated by plug cable removal one at a time; though occasionally removing #1 didn't seem to make as much difference.

 

[oldpilgrim]

you videos are all marked 'private' and we can't see them.

 

[Soundguy]

if killing cyls didnt effect knock, and it's not metalic, and it knocks when water pump not turning.. then it is sounding like it could be a mains issue.. hmm... unless perhaps a thrust problem.

 

[oldpilgrim]

I would think if it was a thrust issue, then you'd see the crank pulley moving in and out.

Not metallic? Timing gear.

 

[Soundguy]

he did see a wobble. wonder about the cam.

i wonder if he feels tapping on t he timing cover...

 

[oldpilgrim]

when tried with pry bar, pulley does not move up and down and there is no detecteble front/back motion. Pulley appears tight. .......................
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I don't pick the knock up with a stethoscope on the front bearing area or anywhere else on the engine body; weird or what?

Here he says there is no noticeable front/back motion. I guess the flywheel/clutch weight could make it difficult to check for that kind of motion, but I have seen it before using a pry bar to move the crankshaft.

If there was a crankshaft thrust issue, he'd hear the noise throughout the engine, I would think. If it were a camshaft thrust issue, it might sound like he says. I think the problem is on the camshaft area or gear by his description.

If it were a rod, the spark removal test would tell it. Rod bearings rattle/pound under no load.

If it were a crankshaft issue, he would not be able produce the sound like he did as the engine would have to be under load to hear it. He'd also hear it throughout the engine.

So, no spark and he still has the noise...not a rod bearing.

Sound occurs without stress on engine....not a main bearing.

That leaves the camshaft/gear or a worn wrist pin........................

Are we getting near it yet?

 

[Soundguy]

i'm betting camshaft myself. the wrist pin will change some with load.. if he checks the front cover ( since he has the belt off ) he might feel it hammering.

 

[Crinton]

Thanks, Soundguy and OldPilgrim - Sorry, I had omitted to publish the videos! New to this UTube stuff - and this too for that matter. Some things to look into from your posts. I'll slip the belt off again and feel the timing gear cover. See/hear the videos, have just published them, and see if that helps. Appreciate your input very much.

 

[CircleRat]

Sorry for jumping in here, but I did see your first video and it definitely looks to me like your pulley is bent. The knocking sound is intermittent (clunkity-clunk- clunk) and it's hard to tell from my crappy little speakers but it doesn't sound like a deep knock such as a crank or connecting rod bearing. Metallic, yes... maybe in the timing cover, or...

Let me ask you this. Is there a front-mounted hydraulic pump on the tractor, with a shaft leading from the pulley adapter to the pump? Some tractors have these to power the front loader. If so, it could be the shaft out of balance hitting the sides of the tunnel through the frame. A bent front pulley could cause this.

 

[Crinton]

Fingers on timing cover - can't detect any tapping. Stethoscope around timing cover area and everything sounds like clockwork, nothing odd. Stethoscope around manifolds, manifold near nuts, valve cover, adjacent head and block areas - bit noisy but no knocks; bit of an occasional tin-on-tin scrapy noise near inner two intake manifold nuts that was a bit odd sounding (and I'm holding the scope 'needle' steady and it's not touching anything else). Got me thinking about camshaft and valves.

Never thought about it before but looks like quite the job to change a belt, and more so with this front end loader rig!