Hi forum, I posted a thread recently on liners for a D7 3T engine. Existing engine number 3T16017, chassis number 3T17311. My parts book listed only two seals for the bottom of the liners and a member explained they changed to three seals due to rust problems. The liner in mention is an old one out of the existing engine and has three 'O' ring seals about 5/32'' or there abouts. I pulled the liners out of another engine I am rebuilding Engine No. 3T11776 for the D7. These liners have flat type seals at the bottom, two larger and one smaller and look like a lot better seal system. I cleaned the rust off and found a number 8B375 on the liner. I am about to order the engine parts and I think my liner and seal numbers are incorrect for this engine from my parts book. The liner number from Cat is 8N-5676 and the seals are 7B-2126/6L-7812.
All the 7B-2126 seals are the same, just the quantity changes. I don't have the latest part number for the liners but 8N-5676 may be correct.
Thanks Old Magnet, I have both the liners side by side and the seal grooves are the same although the top groove on both liners is not as wide as the bottom two. I have ordered the 7B-2126 seals. I don't know the profile of the new seals but the seals I removed are different between the two liners. I think someone has used 'O' rings as a substitute on one. Anyway thanks again.
The seals start out as round o-rings but become squared off in use. Do not use a petroleum product to aid in seating the o-rings. Tire mounting soap works the best.
I always used a cooking grease product as Crisco, thick, water soluble somewhat and does not affect the O-rings. Lard works as well as not invasive to the seals, anything organic not petroleum based.
On liner seals we always used vegetable oil. With the main exception on Cummins. Those had a wide flat top seal that was suppose to be dipped in motor oil just before line was installed. I believe that was to cause them to swell up slightly to act as a buffer at the top of the lower bore.
I use Dawn dishwashing soap. Keeps my hands soft LOL. I always got a kick out of Cascade boxes sitting on our local Cat dealer's parts rack. It has an actual Cat part number. It's used to clean cooling systems after an oil cooler failure.
Yes at one time we used the liquid soap but changed to the vegetable oil thinking it would mix better with the engine oil.
I thought newer engine oils had detergents in them anyway LOL.