Rear Main Seal
August 15th, 2018, 09:42 AM
#1
Kyle
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Join Date: Feb 2018
Location: Annapolis, MD
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Rear Main Seal
I saw plenty of people saying that the Ford 460 seal works great, and after cutting it down to metal on the bottom it fits it the block perfectly (except for when it snaps out and hits me in the face). But it’s too long! What do I do?
Last edited by 87Brougham; August 15th, 2018 at 09:43 AM. Reason: Should I just cut both ends? Or did I get the wrong seal for 1972 Oldsmobile 350
August 15th, 2018, 09:56 AM
#4
Kyle
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Location: Annapolis, MD
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August 15th, 2018, 10:22 AM
#6
Kyle
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Ah, Bill Trovato said the 350 used ford 460, the diesel must have a different crank. Anyways... would cutting this do harm even if I make it fit exactly? Just wondering before I go out and buy the 292. I leave for school tomorrow and I just want to get the engine sealed up because I don't want all the work I paid for to rust up while I am gone. Surely you understand.
August 15th, 2018, 02:53 PM
#7
Old(s) Fart
Join Date: Mar 2007
Location: Northern VA
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Ah, Bill Trovato said the 350 used ford 460, the diesel must have a different crank. Anyways... would cutting this do harm even if I make it fit exactly? Just wondering before I go out and buy the 292. I leave for school tomorrow and I just want to get the engine sealed up because I don't want all the work I paid for to rust up while I am gone. Surely you understand.
August 15th, 2018, 03:19 PM
#9
Kyle
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yeah I think it fits pretty nice, my neighbor who knows more about cars is coming over later tonight to tell me if it fits fine or is too tight, and he is gonna help me cut it, he told me not to cut it flush, but some other way.
August 15th, 2018, 04:08 PM
#10
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Location: Dallas-Fort Worth
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X2 go buy the 292 seal and relax. I cannot tell how many parts I bought for my build that did not fit, even correct part numbers on the label, but that was not in the box! I would not want it to leak after all your hard work...
August 15th, 2018, 04:11 PM
#11
Kyle
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August 15th, 2018, 05:14 PM
#12
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Yes sir!! don't worry about the small stuff on your build. I have a "bad" water pump to change. So far the 64 F-85 is never been on the road for any distance!! Probably off shore rebuild with a weak impeller. AND this is not a "walk in the park repair". I need to pull the electric fans with the radiator etc. But I do Love my Olds...
August 15th, 2018, 07:23 PM
#13
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Join Date: May 2011
Location: Pontiac, MI
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The last 2 small blocks I built I got the gasket kits from OPP. The first one was ran from 05 to 2016 (sold car) and never leaked a drop and I beat the **** out of it. My current build doesn't have many miles on it, built in 09 and first started last spring. Just got done hammering on it on Woodward, running great. Surprised a few Chebbies and a couple Furds for a smog era boat. Put the seal in slightly off set in the block and cap and use a small dab of good engine rtv on the corners.
Last edited by ragz442; August 15th, 2018 at 07:32 PM. Reason: changed date
August 15th, 2018, 07:30 PM
#14
Kyle
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Yes sir!! don't worry about the small stuff on your build. I have a "bad" water pump to change. So far the 64 F-85 is never been on the road for any distance!! Probably off shore rebuild with a weak impeller. AND this is not a "walk in the park repair". I need to pull the electric fans with the radiator etc. But I do Love my Olds...
August 16th, 2018, 08:43 AM
#15
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Location: Rogues Island, USA
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Isn't the diameter smaller on the 350 journal? If so you probably kinked the seal into something other than a half circle as designed. Get the correct seal instead of trying to modify the wrong one.
August 16th, 2018, 10:04 AM
#16
Old(s) Fart
Join Date: Mar 2007
Location: Northern VA
Posts: 47,289
Do not trim or otherwise shave the seal. If it doesn't fit, get a correct one. The correct FelPro seal for an SBO (BS6141) is under $12 at RockAuto.
November 17th, 2018, 10:56 AM
#18
Kyle
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November 18th, 2018, 06:24 AM
#19
Out of Line, Everytime😉
Join Date: Dec 2006
Location: Melville, Saskatchewan
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It is a rubber seal, the 292 Ford seal fits the Olds 260 through 403. https://www.summitracing.com/int/parts/fel-bs6141/m I have used the Supercars Unlimited rubber rear main which no doubt the one above without the straight pieces. I have also used the AMC 6 cylinder seal with the ears cut off. https://www.summitracing.com/parts/f... It is a tighter fit but easy to install with the crank out like your motor.
December 12th, 2018, 02:53 PM
#20
Running On Empty
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This is not an engine-off rear main seal change. I ordered (what I read & researched to be) the correct rear main seal [FEL-PRO BS130442 - Rear Main Seal Set; Rope; Improved design]. But, then I read this post!
QUESTIONS:
(1) I should, instead use the FelPro seal (BS6141) - is this correct? Even though I have found no vendor who lists this as the seal for a SBO (350cid). I'm double-checking my state-of-confusion - please, pardon my ignorance. I'd prefer to trust the knowledge of you guys who have changed these outs - this is why I am double-checking - I may have lost my mind (it's happened);
(2) I have no idea at this point (I have not removed the oil pan, yet - that begins tomorrow), if the rear main seals have ever been replaced on this vehicle - I'm suspecting they have not. My preconceived notion is to expect a rope seal on both the upper & lower seals. This is a minuscule amount of seepage, I don't want to turn it into a leaking faucet. Should I replace both the upper & the lower with the FelPro (BS6141)? My mind is suggesting the possibility of replacing only the lower. Thoughts?
Thanks very much for your time!
EDIT: On edit & doing more research, I have found elsewhere the BS6141 is correct. I'm not sure why two vendors (RockAuto & SummitRacing) both list the FEL-PRO BS130442 for the 1971 Oldsmobile Cutlass 350cid. ARGH!
Last edited by Vintage Chief; December 12th, 2018 at 03:15 PM. Reason: spelling
December 12th, 2018, 04:38 PM
#21
Out of Line, Everytime😉
Join Date: Dec 2006
Location: Melville, Saskatchewan
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Is the motor out if the car? If not, getting the rope seal out can be a bitch, installing the rubber rear main is much easier. i had to loosen all the mains and remove the rear cap and bend a round file to tap the old rope seal out.
December 12th, 2018, 04:41 PM
#22
Running On Empty
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This is not an engine-off rear main seal change.
December 13th, 2018, 04:49 AM
#26
Old(s) Fart
Join Date: Mar 2007
Location: Northern VA
Posts: 47,289
1) You'll find nothing in the CSM about a neoprene rear main seal because the only factory seal was rope
2) No one lists the BS6141 seal as fitting Olds because it is designed to be a FORD seal for the Y-block. The Oldsmobile community has shown over the years that it also works in the SBO. FelPro does not list it this way. Don't lose any more sleep over that.
3) You must replace both halves of the seal as a set. You cannot use rope on top and rubber on the bottom.
4) Oldsmobile specialty vendors who sell special "Oldsmobile" neoprene seals simply take the FelPro seal, repackage it, and sell it for about ten times what RockAuto sells them for.
December 13th, 2018, 05:23 AM
#27
Running On Empty
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I'm sorry, but you are making this WAAAAY harder than it is.
1) You'll find nothing in the CSM about a neoprene rear main seal because the only factory seal was rope
2) No one lists the BS6141 seal as fitting Olds because it is designed to be a FORD seal for the Y-block. The Oldsmobile community has shown over the years that it also works in the SBO. FelPro does not list it this way. Don't lose any more sleep over that.
3) You must replace both halves of the seal as a set. You cannot use rope on top and rubber on the bottom.
4) Oldsmobile specialty vendors who sell special "Oldsmobile" neoprene seals simply take the FelPro seal, repackage it, and sell it for about ten times what RockAuto sells them for.
1) You'll find nothing in the CSM about a neoprene rear main seal because the only factory seal was rope
2) No one lists the BS6141 seal as fitting Olds because it is designed to be a FORD seal for the Y-block. The Oldsmobile community has shown over the years that it also works in the SBO. FelPro does not list it this way. Don't lose any more sleep over that.
3) You must replace both halves of the seal as a set. You cannot use rope on top and rubber on the bottom.
4) Oldsmobile specialty vendors who sell special "Oldsmobile" neoprene seals simply take the FelPro seal, repackage it, and sell it for about ten times what RockAuto sells them for.
2) Will not lose any more sleep over it. Very glad I found this post
3) Honestly, I was considering replacing the bottom rear main seal with the same material as the top rear main seal - rope. (Albeit, why I have referenced the FEL-PRO BS130442 - Rear Main Seal Set; Rope; Improved design]. Just a consideration.
4) Again, I was not referencing neoprene anywhere - I ordered the FEL-PRO BS130442 - Rear Main Seal Set; Rope; Improved design.
At the end of the day, I appreciate your input and sage advice. Glad to have found this post. Thank you!
I'll most likely replace both the top & bottom with the BS6141. The top rear main seal rope will most likely be a PITA to remove.
Last edited by Vintage Chief; December 13th, 2018 at 05:26 AM.
December 13th, 2018, 08:16 AM
#28
Out of Line, Everytime😉
Join Date: Dec 2006
Location: Melville, Saskatchewan
Posts: 8,915
It will be a bitch, if it's the original rope seal to remove. I have used both the Ford 292 seal, the one from Supercars Unlimited, I needed other stuff anyway, an easy fit. The AMC 252 straight 6 rubber rear main seal also works with the "ears" trimmed off. It actually fits tighter, it can be more of a challenge to install with the crank in the motor. Most say offset the seal with a dab of RTV, where the two parts join and where the rear main cap meets the block.
December 13th, 2018, 08:24 AM
#29
Old(s) Fart
Join Date: Mar 2007
Location: Northern VA
Posts: 47,289
Your previous post made it sound like reading the CSM was causing the confusion about the neoprene seal. Sorry if I read too much into that.
December 13th, 2018, 10:18 AM
#30
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December 13th, 2018, 10:19 AM
#31
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