I had my 1954 Chevy car 235 motor out of the car and on the stand so I decided to go ahead and replace the rear main oil seal with a new rope seal. Not sure if it was leaking or not but seemed like a good thing to do while the engine was out of the car. Once I pulled it apart I saw that someone had replaced the original rope seal with a rubber two piece seal. (actually part rubber and part metal but not that it matters) The rubber two piece seal looks flawless which leads to think that the previous owner (who I'm no longer in contact with) replaced the seal right before I bought the car. It looks brand new. The rubber seal looks to be in such good shape that I think I'll just leave it alone. There's a good chance I'll be replacing this engine in the next year or two (due to crack in block which I sealed with JB Weld) and I'm not worried if there is a small amount of oil leak anyways. Am I being crazy? Should I go ahead and replace anyways? I do have an extra rope seal sitting on the shelf but I'm not too excited to do the job if I can avoid it. Next question, when I took the rear main seal cap (0.105) off I saw two thin silver shims. I took them off the block and set them aside but these shims look to be one time use anyways so now I need to either get new ones or but the rear main seal cap back on without them. Do I need the rear seal shims? Not sure how important they are. Finally, when I went to the master parts and accessories catalog (URL below) I was able to ID the shim part numbers. Based on the diagram the part number is 0.153. However, when I went to the Chevy's of the 40's catalog to look up the part they list the part as being for 1940 to 1950 engines. In their catalog the part number is 609121. I'm not sure what to make of this. Do I need to replace the shims or not? Also, I'm hunting for the manual that walks you step by step through replacing the rear main oil seal. I'm ***uming I won't replace it now but I still want to print it out so I have it when I need it. If anyone has a pointer to it online please let me know. I will attach pics of what I'm working with. After I post this thread I'll post a second thread that details how I tried to repair my cracked block with JB weld. I'll include pics for anyone that wants to check it out. Also, I just painted my 1954 Chevy Bel Air in the garage. Hope to have it done by Spring. wish me luck. For reference: http://chevy.oldcarmanualproject.com/1929_54chevyparts/info/089.HTM
Reuse the old shims. Chevy used shims on the mains if need up to about 54. Later engines never used them. Buy a "Motor's" manual off ebay that covers the years of your car ,best $15-20 you will ever spend.
Go buy a stick of Plastigage. Check the clearance without & with the shims, adjust & stick it back together. If your block is cracked but holds water, just run it till it drops. '54 castings are known to be soft. If it don't smoke or leak, run it ...
The two above gave good advice. I will add 2 cents worth. Run a finger dipped on oil over the exposed part of the seal so it doesnt start dry. Several drops of oil on the threads and under the heads of the main bearing bolts to be sure the bolt torque is accurate. Use the old shims as often as you need. They will not change thickness. Oil the bottom half of the bearing before final ***embly.
Perfect. Thanks everyone. I'll reuse the old shims. That makes sense. I'll also follow your tips Ole don. JohnEvans, good tip. I know I need to pick up a manual on ebay. I'll do it this week. Thanks everyone. You folks always come through.
Re use your old shims. They are a thrust washer which keeps your crank shaft from moving forward/backwards
I believe you are mistaken. They may be on the thrust main bearing, but the shims have absolutely nothing to do with crankshaft thrust, only bearing clearance.
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