This last weekend I was taking up the rods in our '26. #1 was pretty loose and the Babbitt had worn a grove in the front edge of bearing. The rod itself seems under tension, pushing towards the front of the engine and there is actually space now on the back side of the journal.
Is this from a bent rod? We have run this car a lot and we are only experiencing this problem now.
Anyway, I took one shim out of each side, put it back together and started it yesterday. I ran it for a very short time (less than 1min) and it started to squeal so I shut it down right away. I went to crank it over by hand and it was very tight and got to the point that it wouldn't turn over. I came back later once everything was cooled off and it turned over but was very tight at first. for every revolution, it gets real tight for about 1/4 of a revolution then is easier for the rest of it. My guess is that it is machining a grove further into the Babbitt since it is now tightened. Any help is greatly appreciated.
Don't like to hear that squeal. Do you have an external oil line for the #1 and if so is it clogged? How about the internal oil line is it clogged?
We have both. I'll check them tonight. That could be it. I had just filled it with oil so it would have had some right at the beginning if those lines are clogged.
Really don't like that tight and loose business. Clogged oil lines aside I think you need to go back in for another look at that rod.
Tight and loose causes me to wonder if the journal is no longer round.
That Rod is out of alignment!
Tightening it again, just cocked it tighter again, in an out of alignment condition.
Rods don't wear grooves in pins, unless the rods are bent.
That's what I was thinking Herm. it will be coming out. One other thing and I don't know if this is because it is bent or not but the cap did not want to come off when I unbolted it. I realize they are somewhat tight but this was really stubborn.
Look at all the rods. Is #1 the only one that has that problem. If the rear main thrust surface is worn, the crankshaft could have moved back in the block. In that case, the timing gears would also be out of alignment with the small gear farther to the rear than the large gear. You can also look up toward the wrist pins and see if they are centered between the piston bosses. If they are farther toward the back than to the front it would be another indication that the crankshaft has been moved toward the rear.
However I think that Herm has hit the nail on the head. Especially if you notice the problem only affects #1. The easiest fix would be to replace or straighten #1 rod. But you need to also check the crankshaft bearing for taper and roundness. If out of round, you will need to also grind the crankshaft and a complete rebuild should be done while the engine is out. Although it costs more to rebuild the entire engine than to fix one problem at a time, in the long run it will take less labor and money to fix everything needing to be fixed at one time.
If one rod is out, they should be all checked.
The other 3 may not be as bad, but will all be off some what.
They don't get bent in an engine, they were out of alignment before installation.
All rods have to be checked, no matter what!
Twist and bend, Yes, but always off set also.
I don't doubt you one bit Herm, but why is it causing a problem all of a sudden? we have probably put 3000 miles on this car plus whatever it had on before we bought it.
It takes a while to wear to what you ended up with at this time.
The rod through stress had worn off the stress point, and when you tightened it, pulled it out of the position that it worn in.
The reason the cap was hard to get off, is the fault of the rod builder, as he didn't do his job of bolt alignment. He either didn't know, or didn't care.
Thanks Herm, I really appreciate your wealth of knowledge. I'll be contacting you about how to move forward with this soon.
'They don't get bent in an engine, they were out of alignment before installation'
Now Herm I'm sure you know or should know better!
Ned, What Herm has said, it is possible that one or more rods are out of alignment from the rod rebuilder failing to double check his work.
BUT! several other reasons can also put them out over many miles of an engines life.
The way the wrist pin was tightened when fitting a piston.
Hydro Lock, from a leaking or blown head gasket.
Detonation, far to advanced.
Fuel mixture, running to lean will make the exhaust valve side of the bore run to hot an crab the piston.
Same as poor lubrication.
Over heating the engine.
That's not just me rambling, all documented reasons in many technical and work shop publications.
Now Herm I'm sure you know or should know better! "END QUOTE"
And Frank, I am real Dam sure you don't.
Thanks Herm, I didn't expect anything more from you other than a derogatory remark.
So now is the question where a lot of you will say "no way fix it right" which I agree with but..... What would it hurt to run this engine for around town stuff until I have another engine built up? I realize it's not going to fix itself and will knock but the Babbitt is already bad in the rod.
I'm all for doing it right the first time but as long as I'm not going to throw a rod through the side of the block I wouldn't be opposed to driving this around town how it is.
How do you know that you won't throw a rod through the side of the block? And also if the wrist pin moves too far to one side of the piston, it could put a deep score in the cylinder. I think you should fix the problem even if you just replace the one rod. But better rebuild or overhaul the entire engine.
I like to have 3 Model T's. One to drive, one to work on and one for spare parts. I have them all running now, but if I get a severe problem in one of them, I will fix it and still have another to drive.
You don't need to have another engine built. Just get a rebabbitted rod and fit it in there. I helped my friend put 4 such rods in his T. It's been doing great for at least 6 years now.
Thanks all. I think I'm going to try Jerry's method and try just replacing the rods. I'll make sure the journals are round first. This engine was rebuilt before we got the car, the quality of the rebuild is now questionable.
Are any of the suppliers' rods checked for straightness or do I have to buy them then take them to someone to make sure they are straight?
Look them over and have them checked! Not trying to knock anyone's work, we all let things slip by at times. KGB
Ned -- Ron's Machine Shop in Shandon, OH is the place to have your rods redone. They'll be sure they're straightened, and re-babbit them (if necessary) to fit your crankshaft journals.
p.s. -- Be sure to mike your journals to be sure they're round. If they're a thousandth or more out of round, the new babbit won't last long.