OK Guys, I've looked at the thread on replacing the 'rope packing' type of seal, and as it happens, I've helped my Dad do one long ago.... I expected to do the same to my truck... NOT SO! My 1955 Chevy engine has a neoprene seal. I need advice on how to change in place. Pictures of my rear main will be included. On another note, I found that my truck has shims under all the main bearing caps? Normal? or Not? Do I need to plastigage them, or since I've already driven over 600 miles and don't see any wear on the rear main bearing, just don't question the shims? The shims cover the ends of the seal, too. Nate, When you're done with your PT, I'm sure you'll have some good advice, along with several others here. Thanks for the help.
Seriously, I need some input on this please Can I replace this type of seal in place? This type of seal has a steel core, so do I drive it out part way and pull the rest of the way? Once out, can I slide the new one in and expect it to work OK?
I just read an article about doing this on webrodder.com, but the engine was out of the truck and on a stand. The author recommends overlapping the neoprene seal about 3/8" away from the parting line of the cap and block to minimize leak potential. Here's the link: http://webrodder.com/article/stovebolt-stroker-chevy-six-part-13-laying-the-crank-lip-seal-re Damon
Thanks Damon. I read the article, and picked up some useful information. Interesting that the mech. stated that for engines using shimmed main caps, he wouldn't even think of using the silicone seal... Mine has shimmed main caps. Mine is also machined for the silicone seal, not the rope type?? I may be fighting an uphill battle here...
235 Rear Main Seal The shims are *very* important ! do not swap therm side to side . To remove that old seal , determine the exact center of the steel rod within it then use a slightly larger punch to drive it out , it'l stick a bit before beginning to move . Once it moves you can grab the protrusion with pliers and rotate the crankshaft as you pull it out . I suggest loosening all the main bearing caps to lower the crank a bit , most don't bother . It doesn't look old enough to leak , I wonder if the visible overage of red RTV is where it was leaking from ? . Rope seals tend to weep a bit in any case , I'd prolly give the neoprene typ a go unless there's reasons to think it won't work well . I rode in Jr's race cars (both) all day yesterday so no P.T. ~ I think I'll rest most of to - day , I'm beat , sore and tired .
Thanks Nate. Hope you had fun with the race cars! The red RTV was introduced after the mains were torqued, when I installed the oil pan... The seal came out quite easily this afternoon. Hope that's not an indication of poor fit. I don't think a rope seal would be possible in this application as the groove is much smaller than for a rope packing type. I'm keeping the shims with their respective side. Out of curiosity, I plasti-gauged the rear main this afternoon, and found it to have .002 clearance. Exactly what the book calls for, (with shims in place). I've mentioned before that this engine had been overhauled about 12 yrs ago, and only run a few times since then, until I bought it. I'm hoping the long set up time caused the seal to fail, and a new one will do just fine. I checked the main bearing and it's .010 under. The pistons are clearly new as well as the camshaft, to the best of my judgement. I appreciate your input Nate. Wish you continued improvement.
Weepy Main Seal Yeah , the old seal prolly just took a ' set ' in one part of the lip . They're typically very easy to replace , once you get it moving . I *didn't* enjoy the race cars one bit ~ they're both track cars and so sit too close to the pavement and bounce constantly , not what I need whilst wearing a neck brace . The Subie WRX Wagon currently has 400 crankshaft horsepower , can you say " over kill " ? . The RHD JDM Honda Civic Coupe is not as fast but still lowered so much it makes daily driving unpleasant ~ the Subie scraped the pavement on every dip or pothole , I find that stupid but , it's not my car so whatever .
IIRC the 235's used shims under the main caps up through 1957 even though they had bearings from 1954 on. 1958-1962 were true machined to fit mains. Neoprene seals usually do roll out easily once started.
Project finished! Did a test drive of about 5 miles, after idling in drive for about 20 minutes. Checked my drip pan this morning, and no oil! Happy, Happy, Joy, Joy. Need a longer test period before I claim total success though. Additionally, I changed the timing cover gasket, harmonic balancer seal, and put a sleeve on harmonic balancer, cause there was oil coming from up front too. Made the modification to the front main brg. cap so bolts can come in from outside to hold on timing gear cover. BTW, the timing gears were replaced when engine was rebuilt. (For those who will want to know).
Yay ! Doncha like simple solutions ? . I sure do , that's why I remain a I6 man and fairly close to stock . How many idiots do you know who'll jump into a 45 year old rig and drive it across America, gathering tools and oil as he goes along ? . Now that you've fixed it Bilbo , wash & wax it ~ Spring will be here soon , time to drive the wheels off it .
SPRING! Heck Nate, It was 70 degrees here today! If I didn't have a house full of guests, I'd have gone on a 50 mile test drive, maybe over to the other Bill's (Hanlon). Anxious to put a few more miles on it to confirm no oil leaks. It does need a good washing now though. Oil film from engine to tailgate from leak. Will get to that ASAP. Have a plan with B Hanlon to do the door latches on Friday, too.
Bill: Don't clean up the driveway before I get there on Friday. Mine leaks a bit, but not near as bad as how you describe yours. - Bill
Check to see if the side plate stovebolts are tight and not letting oil go down the back side of the block around the bell housing and down. That was the main leak from mine. I was ready to change rear seals before I seen it leaking before one of the shows I was going to last year.
I will take a look, Charles. Thanks for the tip. Bill H., What oil on the drive? I keep one of those tin pans under it. I'll have one waiting for you
shims Hope pics come out wanted to know what year engine was and if it had rear shims I have to replace rear seal
I don't think the presence, or absence, of shims changes much about how the seal is changed.. It's a little bit more nuisance is all. We all need more nuisance in our lives, don't we? A really big help will be if you have the neoprene seal... it's a lot easier to change out in the truck. Good Luck.
