Connecting Rod Orientation

Jeremy in DE · Jan 22, 2013

I'm new to engine work, but after reading a few recent discussions I've got a question.

I recently had my TO30 oil pan off to check bearing clearances. While doing that I noticed it appears that numbers 1, 3 and 4 connecting rods are backward. My manual says "rod correlation marks" should face camshaft and assuming I correctly identified said marks they are backward. Certainly #2 is reversed from the rest.

I take it to reverse them I'd have to pull the head? I'd rather not. I've had it for seven years and never knew, does it matter now just because I do know?

matt p · Jan 22, 2013

Just looked at the manual it says to have #'s toward camshaft and the oil spray hole which is higher up on the rod toward the thrust side of engine opposite the camshaft. Did you reverse the rod caps when you had them off for inspection. check closely their should be a # on the rod as well. If you need to change you will have to pull the head.Check your oil spray hole. this is from the z134 engine manual yours might be a z129

Tony in Mass. · Jan 22, 2013

Umph. Pretend you don't know how to read? Let sleeping dogs lie?
7 years? and who knows how long it ran flawlessly before that?..since going back together all wrong?... but it obviously does the job.
IF, big IF, it 'needed' to be turned around, I would remove the caps, with the piston at the highh point, then turn the crank putting that journal as far down as possible, and see if it can rotate in the sleeve, so that all the rod and cap numbers are facing the cam...
But after all this time? Don't fix it if it ain't broke....
Someday in the distance future, when it needs a complete overhaul, be sure you follow the direction, till then....

Anonymous-0 · Jan 22, 2013

Whew . There just may be enough oil splashed onto the sleeve to make it all work ok .
The rod , and the caps have numbers on them . They should match up when you put the rod bolts in .
If it has run this long without scuffing the sleeve , and piston , ?? I would let it stay .
When I pull a motor , trans , etc. etc. , apart , I set things out in the order that I took them out . Rods , pistons , pushrods ,rocker arms , etc. , go back in the hole / loction that they came out of .
I mark / puncture wound punch flywheels , even take pictures .
It saves having to do jobs over .
good luck

PackardV8 · Jan 22, 2013

Probably just leave it as-is.
A number of possibilites:
1. Look for the correct position of the oil hole in the rod. (caps and rod may have been mismarked at factory)
2. If rod cap is simply just removed and piston/rod assembly rotated for correct orientation then piston will be backwards IF psiton has a front and back to it. OR maybe not. POssible that rod was put on piston wrong and therefore rod is backewards because piston/rod assembly was installed using front of piston as reference.

3.HAve to first determine if there is a "front" position for piston.
4.determine if rod in fact has an oil hole and it's correct position.
5. Determine that rod is not placed on piston backwards.

ALL of the above points have to be considered. Simply changing position of just one part might very well throw the other parts out of correct position. There is always (tho slim) possibility of incorrect marking of parts and or improper manufacture.

Note that rods assembled to pistons BACKWARDS is very common mistake made in engine building. Quite possible the rod is on the piston backwards.

2tractors · Jan 23, 2013

Mine had 2 and 3 in the wrong hole but with a reground crank it got back to normal.

Jeremy in DE · Jan 23, 2013

Thank you for the helpful comments. I have it back together at the moment since I needed my tractor for some projects.

Even thought I'm fairly confident some of the connecting rods are backward, if I understood correctly I probably should check the oil spray holes because that will indicate for certain. But even so, it seems the consensus is that since it's run this long already it's probably not worth the work just to get everything aligned correctly. If, however, I have it apart someday then definitely make it right.

What is likely to suffer most from the reversed connecting rods? Wear inside the sleeves? What symptoms should I watch for in the comings years?

I like this tractor. Someday I hope to give it a half-decent restoration. In the meanwhile it's a working tool on my little farm. I don't put many hours on it each year--probably 2-4 each week during the growing season and less during the winter--but it is indispensable for certain tasks.

Anonymous-0 · Jan 25, 2013

Im a engine rebuilder here. Just leave it alone. Why? Our engine oils ARE SO MUCH BETTER than 50 years ago. They (the new oils) have your back now, Rest easy!!

Connecting Rod Orientation

Jeremy in DE

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matt p

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Tony in Mass.

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Anonymous-0

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PackardV8

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2tractors

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Jeremy in DE

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Anonymous-0

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