I was reading another thread where the discussion turned to the removal of the oil filter bolt. I remembered reading Honda Service Bulletin #13, copy attached, which described the change in the bolt head size from 14mm to 12 mm to help prevent the overtightening of the bolt and possible damage to the oil filter case. Note the finned case replaced the smooth case as the finned case was stronger.
I recently purchased a replacement oil filter bolt (15420-300-020) from Honda that came in a sealed Honda parts bag. I purchased the bolt in case I damaged the bolt when I removed the existing bolt after 35 years. The old bolt turned out easily with a socket wrench. The old bolt was purchased in 1972 as a replacement for a bolt that required the use of visegrips to remove it.
Now for the quandaries.
Quandary No.1
The new bolt is slightly longer than the old bolt. The old bolt has a zinc type coating while the new bolts appears to have a cadmium type plating. The holes in both bolts have the same pattern except the holes in the old bolt are slightly countersunk with a more pronounced countersink towards the engine side of the bolt. Also, the head the new bolt is taller than the old bolt. Any ideas why these bolts are different?
Quandary No. 2
The parts fiche calls foe a 15x2.5 o-ring between the flange of the oil filter bolt and the oil filter case. In the case of the existing bolt there is not an o-ring but there is a three step flat rubber washer (unless Honda called it an o-ring). The two outer steps are the same diameter and are smaller than the center step. The flanged washer prevents the bolt flange in coming in direct contact with the oil filter case thereby preventing the metal surfaces bonding together. I believe the bolt that originally came with the K1 did not have the stepped flat washer, and the bolt flange and oil filter case bonded together which made it very difficult to remove. Any thoughts, or am I just dreaming?
Thanks
Harry O.
I will post the pics and service bulletin separately
