Engine knock now? Troubleshooting help needed.

bigwigbuster · Jul 15, 2014

I recently completed having valves on 1950 8n ground...due to poor power under load. Completed reassembly and started tractor. Some smoking...but had some previously. My new problem is I know hear a fairly loud knocking taking place in the engine that previously did not exist! Very concerned about running it now! I'm new to this kind of work on tractors...so all guidance and help would be very much appreciated! Trying to smile! :x Dave

JCinKY · Jul 15, 2014

Is it a full on knock or just tapping? Do you have adjustable lifters, if so did you adjust them? Was the engine completely disassembled? Basically, need more info.

They all tap to some degree. That's the nature of flat tappet cams and solid lifters.

bigwigbuster · Jul 15, 2014

It is more then a tapping. A knock would be a more appropriate description of the engine noise. No the entire engine was not disassemble...just disassemble thing necessary to get head off to get to the valves and have them ground. Yes it has adjustable lifters that we were able to reach and adjusted by removing side plates. They were adjusted as per standard settings for the 8n. Thank you.

Roger in Iowa · Jul 15, 2014

Is it possible you installed a thinner head gasket and piston(s) are hitting head?

Charner MS · Jul 15, 2014

If you have the head off as recommended check the sleeves. Make sure all are tight. If one is loose it will move upward and allow oil into the firing chamber, thus smoke, and when it resets it has a knock sound. Sleeve retainer will secure the sleeve.

Tall T · Jul 15, 2014

The old machinists i learned from would always advise me to do rings and rod bearings on a high mileage/hours engine after a good grind especially if the head was shaved.

A few things can happen when a very high miles or hours engine gets a machine shop quality valve servicing.

The added compression can cause the top rings to smack the cylinder wall ridge, thus breaking them and bringing about serious white smoke.

The added compression can make otherwise moderate wrist pin slop distinctly noisier. Wrist pins kind of "chuckle" like big marbles in a wooden box.

Excessive rod bearing clearance can suddenly become an audible knocking sound.

When you rev it up does the knocking sound just get faster or does it cut out? Did you plane the head?

Maybe pick up a mechanic's stethoscope (I think mine is a KD tool) or use a length of rubber hose to listen to the oil pan and the block and the lifter gallery. Good luck. Terry

bigwigbuster · Jul 15, 2014

Many thanks for contributions thus far! I will continue to update as I work my way through guidance provided. 1. head gasket was supposedly same size. 2. head was not planed/shaved. 3. Sleeves were checked prior to reassembly and seemed tight. I will attempt to get ahold of a mechanics stethoscope in order to better isolate where the knock seems to be coming from. Again many thanks! :wink:

Money Pit · Jul 15, 2014

rubber hose? new one on me. must act as a conduit for the sound?

a cheap route is a length of wood; it conducts sound pretty good. not as good a a stehascope but a heck of a lot cheaper. if it doesn't help you can get the 'scope later.

Tall T · Jul 15, 2014

Ha Ha

When I wrote that i was trying to remember if it was a stick or a hose!

I've had my Stethoscope for 35 years so I forget.

P.S.
My stethoscope sound goes from solid probe through rubber tubing so here's an idea:
Put a dowel into the end of a rubber hose and touch the dowel to the block & pan. Put a small funnel in the other end to fit over the ear.

bigwigbuster · Jul 15, 2014

Hell you guys are great! lol I can see I've got a lot to learn about this tractor...but with all the teachers/experience here...I'm feeling a little better about the possibilities of being able to ultimately handle the job at a reasonable cost! Thanks!

ASEguy · Jul 15, 2014

The first thing I would check is oil pressure with a known good gauge. If you do not have oil pressure do not run the engine to locate the noise or you could find it the hard way. If you do have decent oil pressure, use a stethoscope to help with location. A timing light hooked to different plugs can isolate the noise to a specific cylinder. That's when the flash and knock occur simultaneously. It is possible it's carbon, but run the other tests first. Did you run compression prior to the valve job? If so what were the readings.

Engine knock now? Troubleshooting help needed.

bigwigbuster

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JCinKY

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Roger in Iowa

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Charner MS

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Tall T

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Money Pit

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ASEguy

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