Help diagnose TEA20 engine knock

Well, if nothing else I learned some rudimentary You Tube skills.

Anyone with the patience to watch (and listen) to this seven minute video of my tractor, I'd appreciate feedback on a stumbling knock I've mentioned here before.

Seems to be present at idle, then under load, but will disappear as the load decreases for a run down a hill. I don't know the last time the valves were adjusted so perhaps that's a potential culprit.

I've also mentioned before my oil pressure will start off fine, then drop across the course of twenty minutes to about 8 lbs of pressure. The knock seems unaffected by this. It's present both at full pressure and low pressure...

Other than the knock and oil pressure (ha!) it runs ok, pulls well, isn't overheating, turns over easily. For the most part starts on half a spin (video excepted!).

Some of the local guys who have heard it say it's nothing to worry about but I have a hard time accepting metal-on-metal sounds of any sort as nothing to worry about.

Anyway, forgive the camera work and subtitle spelling mistakes. Hopefully the camera's mic was good enough to pick up the noise.

All thoughts welcome!

http://www.youtube.com/watch?v=1CFbBdF9gbk

That sure is pretty country around your place!! You obviously get more rain than we do here in Outback Australia!!

That engine knock does not sound good - I would not be ignoring it! You may have some expensive decisions to make.

I have a suspicion ... whilst the engine is idling, take off one spark plug lead at a time and see if the knock disappears, which will identify the offending cylinder.

Bob in Oz

In my opion, the ticking sound that I hear sounds like you have a valve with excessive lash. Mains would sound more like a thumping. My TO-30 makes that same tick and I know I had a problem adjusting the #1 valve hot and running so I left it on the loose side. Mine tends to go away when the engine warms up and all the clearances are stabilized. I need to get after it when I lay the tractor up to replace the old 1-1/8" pto shaft but I need it right now so it'll keep.

I'd be more concerned about 8 psi hot oil pressure at idle. I don't know what the specs on the Standard engine are but the Continental's allow no less thatn 15 psi at 400 rpm with the engine at operaing temperature. Perhaps John(UK) or Assie DOc or Bob from Oz can give you some specifics there regarding the oil pressure spec.

By the way, nice looking tractor!
By the way, check your spark. It should be FAT AND BLUISH-WHITE. Your TEA will start easier.

[b:809a4a1881]Jerry[/b:809a4a1881]. Hard to diagnose from 12,000 miles away and the Youtube audio is not the best for noise diagnosis! Any diagnosis can only be at best, a guess.

I thought excessive valve tappet clearance would be more a "tick" whereas that noise sounds like a deeper tone "thump" or knock? That noise, coupled with the 8 PSI oil pressure (if the oil pressure gauge is correct...) gave me concern it may be excessive clearance in a big end bearing or little end bush (wrist pin??). If it goes away when the plug lead is disconnected, the noise will be in the engine bottom end, rather than valve gear/tappets.

An oil sample analysis could detect the problem from any metal particles in the oil filter. I've only ever used it for aircraft engines and have no idea what it would cost. Looks like Exxon - Mobil carry out oil sample testing in the USA.

I would not be putting that engine under load or running it too much until the source of the noise is clearly identified, lest far more expensive problems arise.........

My TEA20 (85 mm engine) idles hot around 30 PSI and pressure relief valve activates around 60 PSI. The Ferguson reference book states:

"Engine lubrication is supplied at a pressure of 40 - 60 lb per sq. inch. to the crankshaft bearings and also to the timing chain and governor."

Click to expand...

From the starter (and alternator), that looks like an 80 mm bore engine, converted to 12 volts. I think the lubrication system and oil pressure should be the same as the 85 mm engine.

Bob in Oz

I spent a lot of time around jet nozzle test laboratories, wind tunnels, and turbine engine ground test facilies, etc so I can't claim to have the best of hearing, Bob.
As i said I didn't hear any thumping from mains but I did hear the ticking sound of a valve with excessive lash. You may be capable of hearing in that low frequency range so I won't argue about what you heard.
Since the spec calls for 30 psi at idle with an engine at operating temperture, 8 psi is surely a problem. Now whether it's due to a stuck open relief valve or worn mains, or both. I'd be concerned more about that then the ticking I heard. Furthermore, it's a lot easier to fix the valve lash, or eliminate it as a possibility if that's what the problem is, then to check and fix the mains or rod bearings. So I'd go there first.
Just my opinion.

Bob, Jerry -- thanks very much for the input. I have tried removing plug wires one at a time while the engine is running and it has no impact on the noise at all -- just keeps merrily clattering along on any three cylinders...

I sent a link to John (UK) who also can't say for sure due to the bad sound quality but says I certainly have to reset those valve clearances and timing at the very least.

He's also of a mind that it may be broken governor parts clattering around inside.

Oil pressure is supposed to be between 40 and 60 apparently so I've got some work ahead of me on the top, bottom, front, and perhaps the inside coming up!

Thanks again for the diagnosis effort.

Bob -- yes it's pretty country up that way and record rainfall in the area this year has kept everything very green. Alas it's beginning to tip into serious fall weather now and winter comes on quickly. I may not get through the troubleshooting before the old girl gets put up for the winter... There will be lots to keep me pondering til spring!

I'm sure that tick is the valve lash.

If this were my tractor, I'd check the relief valve first and make sure that it is functioning properly and not stuck open. Then I'd rebuild/replace the oil pump. Then if that doesn't solve the oil pressure problem, do the mains and rods. If you were going to redo the lower end, you ought to do the pump anyway as long as you're there. My point is do it first. It may be the root cause of the problem and if it isn't you'd have to replace/rebuild it anyway to do the job right.
Just my opinon.

"I have tried removing plug wires one at a time while the engine is running and it has no impact on the noise at all -- just keeps merrily clattering along on any three cylinders..."

Click to expand...

Then Jerry and John are probably correct - it will probably be in the engine top end. Do you have an auto mechanic's stethascope or even a long screw driver you can hold against various parts of the engine and plug into your ear? That may be better in identifying the area of the noise.

I didn't think of governor - they tend to lose one of the counter weights - but I think governor failure would not cause a rhythmic noise, more likely a continuous rattle. Besides, losing a governor weight usually leads to either serious timing chain failure of a new "engine vent" through the front timing cover!!!

That low oil pressure would worry me. As Jerry suggested, check the oil pressure relief valve and possibly rebuild the oil pump. May pay to also check your oil pressure gauge is reading accurately?

But I'd go look for that noise first to determine the full scope of work you may need to carry out.

Good luck!

Bob in Oz
'53 TEA20

I just took the head off my parts tractor, if there are parts you need and I can help let me know.

sounds like valve train racket to me. Had a few old 235 chevy sixs sounded just like it.
That oil pressure would worry me

Thanks again, all, for the continuing input. And I certainly appreciate the offer of a source for parts, Jeff. I may need them yet.

Going to be heading up to the tractor this weekend and hopefully I can get at least the rocker cover and pan off for a look and pull the oil pump.

Bob -- I do have a mechanic's stethoscope and have been all over the engine. The noise seems loudest towards the top of the block near the front.

I'm going to retry the plug wire exercise just to confirm I'm right about there being no change in sound.

If the knock disappears when a plug lead is removed, it's a fair bet the problem is in the con rod big end or little end - the expensive end of the engine!!!

"The noise seems loudest towards the top of the block near the front."

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That won't discount #1 or #2 con rod little end (wrist pin??) bush but it does sound like your problem may be valves or tappets in #1 or #2 cylinder? That is also in the area of the water pump, governor and timing chain. Try the stethoscope on the rocker cover, water pump housing and timing chain case.

And just a thought without any particular reason, listen below the distributor around the area of the distributor drive down to the oil pump as that "knock" may somehow still be connected with the low oil pressure.

Good luck.

Jeff, I just took the rocker assembly off my Tea20. I've got a bushing loose, turning in the number one intake valve rocker. Anyway, is the locator pin for the end knob just a straight pin that can be driven out with a drift either way?

Al - don't know if you've tried removing that pin yet but the manual seems to agree.

From Section C10 - Rocker Assembly:

"Prior to tapping off the end collar, it is necessary to tap out its locating pin."

(quoted from post at 00:22:21 10/11/08) Al - don't know if you've tried removing that pin yet but the manual seems to agree.

From Section C10 - Rocker Assembly:

"Prior to tapping off the end collar, it is necessary to tap out its locating pin."

Click to expand...

Is that problem (knocking) resolved? I have exactly same problem...

My friend's TEA20 sounded much the same . After much wasted effort checking bearings I found loose and broken governor weights and a slack timing chain were the cause .