Seized Wrist Pin

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Model T Ford Forum: Forum (old): Seized Wrist Pin
Top of pagePrevious messageNext messageBottom of page Link to this message  By tim gray (Timmygray) on Wednesday, January 15, 2003 - 07:18 pm:

I started my 1925 T model ford last Saturday morning. It ran about twenty seconds and started chattering very loudly. I shut it down very quickly and tryed to turn the motor over by hand gently. Well it was LOCKED! I soaked the pistons with light oil via the spark plug holes and she unlocked somewhat. I dropped the inspection cover on the tranny and saw all cylinder were oiled well except the #1 piston which was dry and had aluminum on the cylinder wall. I removed the head and removed the piston. I found the wrist pin was seized tight. The piston of course is trash. This motor was rebuilt about 11 yrs ago and driven only on and off the show trailer. The motor had fresh SAE 30 oil and was full (I check oil and water every time I run one) The motor has it's internal oil line and an external oil line. The pistons are aluminum "Jann" pistons (.040 over) The connecting rods are X grooved and the rod caps are drilled and X grooved with oil dips added. My question .....WHY !!!! this engine was built right it would seem. Has anyone else had this happen. I did hand crank the motor with the "bad" piston removed and it is smooooth.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Fred Houston - Broken Arrow, OK (Fredhouston) on Wednesday, January 15, 2003 - 10:36 pm:

Tim,

Yep, this has happened more often than you might think.

This is exactly what would happen if no oil were going to the front of the engine. What might cause this? Two thoughts.

If you have no oil screen in the tranny and your oil lines are plugged.

Or...if you thought you had oil and didn't. This can happen if only the top spikot is checked. A few drops always come out. A good stream is required.

Otherwise, I don't understand how it could happen on an engine treated with lots of TLC.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Huson (Modelt12) on Wednesday, January 15, 2003 - 11:04 pm:

Tim:

Almost all pistons must have the wrist pin hole honed with a sunnen hone or some other hone. You should be able to put the wrist pin back in the piston after honning and then slap the piston in your cupped hand and have the pin slowly fall out. If you don't do this the piston can crack from slapping against the cylinder wall. I find that the pistons that I get from my supplier has to be honed every time at least one or two and sometimes all four.


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