Center main bolts don't come out

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Model T Ford Forum: Forum 2016: Center main bolts don't come out
Top of pagePrevious messageNext messageBottom of page Link to this message  By Joe Fedullo, Milford MI on Saturday, June 11, 2016 - 01:02 pm:

I was chasing a knock at high speeds and pulled the 3 dip pan. I had some help from a local forum member, Peter Nikolajevs who walked me through the process of taking up the rods. He showed me how to do the first one, and I checked the remaining rods, except for #4 because it just did not look like fun, and shorting #4 did not seem to affect the noise.

Now the fun - Since it was easy to get to and I had not used my 8 point socket in a while, I decided to take a look at the center main... The first square bolt I turned was pretty tight and stayed tight as I turned it. I figured there was a bogered up thread, and I would take it out and chase it. After a few turns, it did not seem to be coming out, so I decided to try the other bolt and see what it did. It was much looser, and stays loose as I turn it, but it also does not seem to be coming out. On the loose bolt, I hear a clicking noise high up every few revolutions.

I assume the center main bolts are threaded directly into the block casting, and if I am having an issue, I might have to figure out how to get those bolts out and helicoil the block.

I am leaning towards putting it back together and going for a ride and dealing with this in the winter...

-Joe


Top of pagePrevious messageNext messageBottom of page Link to this message  By Walter Higgins on Saturday, June 11, 2016 - 01:07 pm:

Look in the space between the #2 and #3 cylinders. You will find nuts on the other end of those bolts.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Saturday, June 11, 2016 - 01:12 pm:

NO! There are castle nuts on top between the 2 and 3 for the center main and in front for the front main. If you have a one piece valve cover engine you need to take the valve cover off to get to the passenger side nut. The other is easy to get to from the drivers side as are the two nuts for the front main. Now that you have started and turned the bolts you really should do the job. They are cotter pined and you may have turned the bolt till the cotter pin is no longer easy to get to.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Joe Fedullo, Milford MI on Saturday, June 11, 2016 - 01:16 pm:

Thanks for the quick replies.

Took a look and there are nuts up top. Now that I know that, this should go a lot easier...

Thanks!
-Joe


Top of pagePrevious messageNext messageBottom of page Link to this message  By keith g barrier Savannah Tn. on Saturday, June 11, 2016 - 04:00 pm:

Joe, also on reinstall look at the square head of the bolt and you will find a small teat, that lets you realign the bolt on install so that the cotter pin will go back in. KGB


Top of pagePrevious messageNext messageBottom of page Link to this message  By Joe Fedullo, Milford MI on Saturday, June 11, 2016 - 04:22 pm:

I decided to put it back together and see how it works before moving on to the mains.

I took a ride to town and stopped at the park Peter and his Cub Scout troop are camping at. I gave some kids Model T rides, and there were smiles all around.

The knock during deceleration is pretty much gone. I hear it faintly on occasion, but only because I am tuned into it. I found a small knock during transient acceleration that was masked by the other one. It is not steady, just seems to happen for a split second sometimes during accel.

The high speed knock is much less, but definitely still there. It is fairly steady, and I really only hear this one above 35 or so. I guess it could be the mains, or it could be just running the motor too fast. Below 35 it is really quiet, so for now, I will just stay under that speed. How fast do you guys cruise?

I did try pulling spark at high speed when the knock was happening and if I retarded it almost halfway the knock disappeared, but engine power went way down.

Thoughts?

-Joe


Top of pagePrevious messageNext messageBottom of page Link to this message  By David Menzies on Tuesday, June 14, 2016 - 04:10 am:

Your crankshaft could be whipping because of a warn rear main. The rear main takes a lot of abuse and if it is warn will cause the crankshaft to whip. In extreme cases can cause the crankshaft to break in half. Some crankshafts become bent only and can be measured when disassembled and require straightening before machining. Any of these conditions may cause knocking. For max life keep your speed down.


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