Rear main seal keeps tearing on bottom half

or to see relation to a 200. I assume the same but not labeled for that motor or yr.
 
Hi, that seal I think is a 2 piece rubber seal, not the rope seal. Good luck
 
At this point i believe you could try a rope seal.
Otherwise i am taking a guess that whoever line bored the block removed too much from the rear main cap & it is smashing the seal into the crankshaft.
Last shot is replace the block & install another crankshaft.
 
bubba22349":2ikrylj8 said:
Simonsalz":2ikrylj8 said:
bubba22349":2ikrylj8 said:
:unsure: I have been a fan and proponent of using the neoprene type rear main seals (because they had less friction "for a little extra free power") since back in the late 1960's, plus I have also mostly used and recommended the FelPro brand. Recently this same issue has come up with severial other people when using the FelPro rear main seals in the early 144, 170, & 200 blocks (i.e. those that originally used a rope seal). Because of this continuing problem I believe that these latest seals are not being made to the orginal Ford Factory specs of the rear main seals like we're used or offered in the past, and or they may even be substituting a seal from another seal application. Anyway this is my theory and because this has now happened with quite a few instances there is definitely a recurring problem over the last approximately 2 or 3 years, of these rear main seal failures. But only by acquiring then doing a side by side comparison and accurate measuring of a new original Ford seal which I think is (C9AZ-6701-B) compared to one of these current FelPro seals will prove this theory.

At this time I don't know if there is another manufacture that makes the correct spec neoprene seal to fit these 200 blocks, so it is my opinion and recommendation not to waste your time installing one or the money to buy one of these seals that FelPro is currently offering. So It also my opion It's just best to use the old tried and true rope type rear main seal. Or unless you would be lucky enough to even find a "NOS" Genuine Ford neoprene rear main seal. To reinstall the rope seal you can make a replacement rear main seal locking pin for the main cap from the end of a small finish nail of the correct diameter and cut it off to fit into the main cap. Good luck (y) :nod: Edited

Would this be it?

Yes that's looks like a Genuine ("NOS") Ford made seal. It would be interesting to measure and compare the Ford seal against the Newer FelPro seal to see how or if they are making them different. :nod:

I’m tempted to order it to check

But also would I be able to measure the felpro seal and compare it to another gasket (full circle neoprene for instance) to see if the crush is different? I may sound like an idiot but it’s evident something is making the seal push too tight on the crank and I just realized the front crank seal has never leaked.
 
wsa111":nbizh0t0 said:
At this point i believe you could try a rope seal.
Otherwise i am taking a guess that whoever line bored the block removed too much from the rear main cap & it is smashing the seal into the crankshaft.
Last shot is replace the block & install another crankshaft.

I got a rope seal (national) but I was told the new rope seals aren’t as good because they don’t contain the abspesbos (if that is spelt right) should I still try the seal? Also someone from the Facebook group recommended I try to use a 235 Chevy rope seal from “best seals (or gasket)” but never explained to me why besides the dimensions being correct) am I missing anything?
 
chad":1exr84n4 said:
or to see relation to a 200. I assume the same but not labeled for that motor or yr.

Yeah! That’s why I didn’t know because I don’t know how these blocks cross from different bores. All I know are the heads are interchangeable
 
Simonsalz":jy73ckj8 said:
bubba22349":jy73ckj8 said:
Simonsalz":jy73ckj8 said:
Would this be it?

Yes that's looks like a Genuine ("NOS") Ford made seal. It would be interesting to measure and compare the Ford seal against the Newer FelPro seal to see how or if they are making them different. :nod:

I’m tempted to order it to check

But also would I be able to measure the felpro seal and compare it to another gasket (full circle neoprene for instance) to see if the crush is different? I may sound like an idiot but it’s evident something is making the seal push too tight on the crank and I just realized the front crank seal has never leaked.

Yes for sure they can be measured. If I had the two seals I would start by setting them on top of each other to examine the difference or making a line around them on paper and use that to see differences. Then you can use a Dial Caliper or a Micrometer to measure the seal thickness and height, all of these would be fairly easy to do except for the seal lips height, this is because if you put too much presure on it its going to start moving. Yes you are right the front seals have been made correctly over the years, and usally outlast the engine. Good luck (y) :nod:
 
bubba22349":2uxdvjxf said:
Simonsalz":2uxdvjxf said:
bubba22349":2uxdvjxf said:
Yes that's looks like a Genuine ("NOS") Ford made seal. It would be interesting to measure and compare the Ford seal against the Newer FelPro seal to see how or if they are making them different. :nod:

I’m tempted to order it to check

But also would I be able to measure the felpro seal and compare it to another gasket (full circle neoprene for instance) to see if the crush is different? I may sound like an idiot but it’s evident something is making the seal push too tight on the crank and I just realized the front crank seal has never leaked.

Yes for sure they can be measured. If I had the two seals I would start by setting them on top of each other to examine the difference or making a line around them on paper and use that to see differences. Then you can use a Dial Caliper or a Micrometer to measure the seal thickness and height, all of these would be fairly easy to do except for the seal lips height, this is because if you put too much presure on it its going to start moving. Yes you are right the front seals have been made correctly over the years, and usally outlast the engine. Good luck (y) :nod:

Sorry i haven’t replied in a while
I ended up finding another block and I pulled the cap to get it measured to see if there is a difference (if there isn’t I’ll get the NOS seal and see if I can find a difference! But also I may just have the new national rope seal installed to see how that would last
 
as U no, doin the same thing gets the same results - X 2 do something different, anything
(take notes, only change 1 thing).

will C what we can do frm here, good luck!
 
bubba22349":347izrjw said:
:unsure: I have been a fan and proponent of using the neoprene type rear main seals (because they had less friction "for a little extra free power") since back in the late 1960's, plus I have also mostly used and recommended the FelPro brand. Recently this same issue has come up with severial other people when using the FelPro rear main seals in the early 144, 170, & 200 blocks (i.e. those that originally used a rope seal). Because of this continuing problem I believe that these latest seals are not being made to the orginal Ford Factory specs of the rear main seals like we're used or offered in the past, and or they may even be substituting a seal from another seal application. Anyway this is my theory and because this has now happened with quite a few instances there is definitely a recurring problem over the last approximately 2 or 3 years, of these rear main seal failures. But only by acquiring then doing a side by side comparison and accurate measuring of a new original Ford seal which I think is (C9AZ-6701-B) compared to one of these current FelPro seals will prove this theory.

At this time I don't know if there is another manufacture that makes the correct spec neoprene seal to fit these 200 blocks, so it is my opinion and recommendation not to waste your time installing one or the money to buy one of these seals that FelPro is currently offering. So It also my opion It's just best to use the old tried and true rope type rear main seal. Or unless you would be lucky enough to even find a "NOS" Genuine Ford neoprene rear main seal. To reinstall the rope seal you can make a replacement rear main seal locking pin for the main cap from the end of a small finish nail of the correct diameter and cut it off to fit into the main cap. Good luck (y) :nod: Edited


Hey! sorry its been a while since i have replied, but i found a NOS rear main seal and installed it, but the leak still persists. but on the bright side, i was told it needs to "swell (because i didnt soak it over night, but i did lubricate the seal)" and that should help with the leak also. i remember when i was cutting the seal to fit it would clear the oil where the crank was mated and id assume when the engine heats the clearance gets even tighter. honestly ill be fine with it, as long as i can make it 3k miles before having to add or buy new oil. but it seems to be dripping rather fast still, but that could be my paranoia. I made sure to follow all proper steps and ive asked many with success in installing rope seals and did as instructed.
 
What do you mean trim the seal to fit ?
I do not remember that needing to be done, that maybe your problem...No crush to make tight.
Let us see what other members say.
 
chad":3sr3qppm said:
as U no, doin the same thing gets the same results - X 2 do something different, anything
(take notes, only change 1 thing).

will C what we can do frm here, good luck!

Hey! hows it been? sorry i haven't responded as ive been busy but im back!
I ended up using a NOS felpro rope rear main seal but it is still leaking, but ive read, and been told, that it has to "swell" so im hoping that it will fix itself soon. also to mention i noticed there was crosshatching on my rear main mating surface (on the crank) but they're not deep by any means. they seem like they were put there and could that be what everyone is talking about when the seal has to "seat"? also to mention ive taken the block and crank to two machine shops and they both said the specs were spot on and the line bore is now good. i really hope this fixed the leak though. also i may buy the national two piece nitrite seal and see where i end up if this rope seal is no good in the future.

the felpro rear main neoprene seal ive been using also shows signs of where like the crank is compressing to much (as you can see its wore down and the letters (stamped on) are gone on the top part near the lip (i can get a picture if need be). but if my block and crank are within spec could that be felpros end? since many have seem to have good luck (minus a few) with the seals?
 
drag-200stang":1wr63jqo said:
What do you mean trim the seal to fit ?
I do not remember that needing to be done, that maybe your problem...No crush to make tight.
Let us see what other members say.


I used a two peice rope seal, sorry if i didn clarify
everyone told me, and the package said to trip flush with cap mating surface.
 
wsa111":3u3ocodq said:
At this point i believe you could try a rope seal.
Otherwise i am taking a guess that whoever line bored the block removed too much from the rear main cap & it is smashing the seal into the crankshaft.
Last shot is replace the block & install another crankshaft.


Both machinists i went to didn't think it was line bored ( going off specs) and the condition of the engine when i first brought it in, i mean the seal housing measured around 4 inches (i dont remember specifically) and the national two peice seal even states the hosing bore is 4 inches (if im correct).
 
Ok that makes sense.
I thought that you were going to try a nos neoprene seal that may be made to the right spec. versus today's offshore stuff.
 
U put the lill pin back in for the rope seal?
"... I made sure to follow all proper steps ..."
like 2 hear more. Similar with the neoprene U may B following best practices (use no other) but I
can't tell.
Also
some here R saying machined/unmachined prts may B interfering...
 
Simonsalz":m94shj42 said:
bubba22349":m94shj42 said:
:unsure: I have been a fan and proponent of using the neoprene type rear main seals (because they had less friction "for a little extra free power") since back in the late 1960's, plus I have also mostly used and recommended the FelPro brand. Recently this same issue has come up with severial other people when using the FelPro rear main seals in the early 144, 170, & 200 blocks (i.e. those that originally used a rope seal). Because of this continuing problem I believe that these latest seals are not being made to the orginal Ford Factory specs of the rear main seals like we're used or offered in the past, and or they may even be substituting a seal from another seal application. Anyway this is my theory and because this has now happened with quite a few instances there is definitely a recurring problem over the last approximately 2 or 3 years, of these rear main seal failures. But only by acquiring then doing a side by side comparison and accurate measuring of a new original Ford seal which I think is (C9AZ-6701-B) compared to one of these current FelPro seals will prove this theory.

At this time I don't know if there is another manufacture that makes the correct spec neoprene seal to fit these 200 blocks, so it is my opinion and recommendation not to waste your time installing one or the money to buy one of these seals that FelPro is currently offering. So It also my opion It's just best to use the old tried and true rope type rear main seal. Or unless you would be lucky enough to even find a "NOS" Genuine Ford neoprene rear main seal. To reinstall the rope seal you can make a replacement rear main seal locking pin for the main cap from the end of a small finish nail of the correct diameter and cut it off to fit into the main cap. Good luck (y) :nod: Edited


Hey! sorry its been a while since i have replied, but i found a NOS rear main seal and installed it, but the leak still persists. but on the bright side, i was told it needs to "swell (because i didnt soak it over night, but i did lubricate the seal)" and that should help with the leak also. i remember when i was cutting the seal to fit it would clear the oil where the crank was mated and id assume when the engine heats the clearance gets even tighter. honestly ill be fine with it, as long as i can make it 3k miles before having to add or buy new oil. but it seems to be dripping rather fast I in still, but that could be my paranoia. I made sure to follow all proper steps and ive asked many with success in installing rope seals and did as instructed.

Hi Simon welcome back! :banghead: Sorry but the rope seal isn't going to swell up with oil over some amount of time and seal itself, nor will the engine heating up help it to seal any better. As the engine warms up its going to expand so this going to depend on the rate of expansion of the parts I the cast iron block, the cast steel crankshaft, vs the rope seal material ect. I am not an engineer but there's a good possibility that it will even leak more when at operating temps.

:unsure: I guess to be able to determine the cause I would need to see some pictures of the install or know what your install procedure was, but I will take a stab at it. There was a tool made to install the rope seals to hammer it into the seal groove to fully seat it. I never had this tool so would use the biggest inpact socket that would fit pushing the seal into place in the groove first and then giving it a couple of light raps with a hammer to fully seat (bottoming the seal into the seal groove) after that I trim the seal ends with a fresh (Sharp) single edge razar blade the ends should be just slightly (proud) above the blocks main caps parting line so that it gives a little bit of a crush fit, you could use a .002 feeler gauge layed beside the seal as a guide for cutting nthe seal. Next Lube the seal surface with pleanty of oil, also clean & lube the cranks seal surface good too, the angle groves on the crank are there to chanel some oil onto the seals surface so the seal will last longer. A new rope seal shouldn't be leaking if installed correctly. Another way to know if the seal is installed correctly is the engine when turned off stops turning quickly due to the amount of friction of the rope seal, until over time and heat its position takes a set. You also need the retaining pin installed in the main cap to keep the seal from spinning in the groove. I have made many of these from about a 4 P finish nail with the pointed end going into seal and then cut off to fit. Sorry for your troubles, Good luck. :nod: Edited
 
drag-200stang":1kue1grb said:
Ok that makes sense.
I thought that you were going to try a nos neoprene seal that may be made to the right spec. versus today's offshore stuff.


I was going too, but I figured since it would be apart it would be easier to install a rope seal then swap over to a 2 peice. I also went for the rope seal because I was recommended by many to go original.
 
chad":2gchazt1 said:
U put the lill pin back in for the rope seal?
"... I made sure to follow all proper steps ..."
like 2 hear more. Similar with the neoprene U may B following best practices (use no other) but I
can't tell.
Also
some here R saying machined/unmachined prts may B interfering...

Yes, the original pin was installed back into the engine and I even was walked through by someone who has successfully installed many rope seals
I installed it as everyone recommended and time after time it all seems to fail.
 
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