rope main seal

[chris 48 P15]

on plymouth flat six

the rope seal is in 2 pcs the top sit behind the crank tried to install no good 

watched video from sniper on rope seals

does crank have to come out

any info 

thanks

[DJK]

The first time I did mine in the vehicle, I loosened the main caps to allow the crank to drop down slightly. The following year I completely rebuilt the engine on a stand, much easier. Had an 80 yo former mechanic assist me in the installation of the rope seal, still leaks slightly!!!

[chris 48 P15]

i just saw these seals on moparpro they use rubber where the rope is 

better like this or better like that

[Sniper]

You best post a link to those moparpro seal as Chrysler made, at least, three different rear main seal setups over the years, none of which interchange and the last iteration was a neoprene setup.

 

This kind of thing is why it is very important for you to post the details of the engine involved, primarily the engine number.  Plymouth flat six as an identifier isn't going to cut it.

 

If this is the seal, I can already tell you it the application listing is wrong and it's not a replacement for the rope setup.

 

https://www.moparpro.com/rear-main-seal-1934-1960-plymouth-dodge-desoto-chrysler/p1535

 

 

[Sniper]

Digging into the manual it appears you should have this style, assuming original 1948 Plymouth engine

 

 

Rope style is this one

 

 

And the last version is this style

 

 

 

[James_Douglas]

I have used the Best 3675 seal type in the 1947 Desoto. It leaks too much.   I have tried it 3 times.

 

After the last time I wrote an email to Best asking for the seal shaft specifications. What is the shaft ID-OD tolerance for this seal. I got bull **** back with no numbers. If they do not even know or will tell you what the shaft size the seal is for...how do you and ones machine shop know how to check if the seal area is too large or too small?

 

My crankshaft in the 1947 Desoto is NOS. It has never been turned. It leaked from day one. I even had a shop that I trust replace the seal in the chance that I am an idiot. Same result.

 

My 1949 Desoto engine that was rebuilt by an outfit in California Called Automotive Engineering in 1963 hardly leaked at all. It has a rope seal.

 

The 265 I am working on is going to get a rope seal and I am also going to use a plate seal on it as well. Since if the block is tapped for the plate seal, not all were, one can use both and they do not interfere with each other as far as  I can tell.

 

James

[chris 48 P15]

thanks all for info

i found engine number p15* 901121

same as vin number does this mean original

where can i find what these numbers tell me if not 

rope seal came of the car

i would prefer not to use rope seal if possible 

will step up my game hen asking questions 

the first seal sniper posted is the one i was referring to 

so can i use neoprene 

[Sniper]

Rope seals tend to leak and they put a lot of drag on the crank.  It's almost an art form installing them anymore, lol.  OEM's quit using them a long time ago for a reason.

 

My core 230 uses the last seal I posted.  It's pretty similar to modern day seals but the engine has to be machined to accept it.  I have no idea if an earlier engine can be machined to accept it.

 

If using the rope and the first seal I posted together works, that might be a good idea.

 

 

[kencombs]

https://www.amazon.com/Lisle-27000-Sneaky-Pete-Tool/dp/B0002SRCJW

 

The above is a listing for a specialty tool set used to replace the upper with the crank in place.  I've done it, a long time ago.  No fun at all in the car, but it can be done.

 

Loosen all the main bearing bolts a couple of turns and pry the crank down into the lower mains.  That provides some room.  When pulling the upper in, also turn the crank as you pull.   Retorque the main caps before trimming the seal ends.

 

Good Luck.

[Dodgeb4ya]

Rope seals do not leak small puddles if installed correctly.

The only easy and proper way to install ropes is engine out and on a stand.

The installation of rope depends on the type of rope seal design and retention in or on the engine.

I have and do use only the factory asbestos/graphite MoPar ropes.

Modern new ropes leak.

The seals need to be carefully pressed and shaped to both the crank and the retainers if used. The ropes need to have oil applied to the surface while being fitted.

As for drag of the rope on the crank...needs to be checked...only way to do it right is with just the crank in the block..no rods or timing chain connected.

Chinese finger to install...nope.

Trying to install ropes in retaining plates up through bell housing...nope.

 

 

[James_Douglas]

I have one late 1940's Victor rear main seal in my stuff. Never used. I have posted photos of it before. That seal, which is the same style as the Best 3675, is MUCH different at the sealing line. The seal has much more surface area on the crankshaft. In addition it has a vulcanized material of some sort over the rubber. Much more contact area and much stronger mating material at the point of contact.

 

I suspect that the available seals of the 3675 type are a cheaper to manufacture versions of the original seals. I know that I had a talk with the owner at Olsen's Gaskets and their take is that many of the seals and gaskets being made are not nearly as good as their earlier version. The cost to tool up to do the better versions is not warranted in the market place. Case in point is the copper sealing rings in the head gaskets. The NOS or early NORS ones had the copper sealing rings around every hole that had water going through it. The replacements that Best makes do not. The cost of tooling for those ring would triple the price I am told.

 

Like I said, the rope seal in the 1949 Desoto engine that was rebuilt in 1963, stored in 1966, and not run again until 2012 leaked less than of any modern seals I have had in any of my flatheads.  I do think there are way to many parameters when dealing with main seals. The size of the journals, the condition of them, the exact type of seal and the installation. Conclusions as to which is a better seal may be a fools errand.

 

Over the next year it will be interesting to see how the seal is when I use a rope.

 

James

[keithb7]

My recent 1953 year engine rebuild had option #1. I bought the Fel-Pro version. BS-6300. I have a leak. I had used a little RTV sparingly at the end butts.  Perhaps its the pan gasket leaking in a corner. Hard to tell exactly. I do notice if I park on a down hill slope, no sign of a drip on the asphalt under rear of engine. 

Edited May 2, 2022 by keithb7

[Booger]

we use to do rope seals with a coat hanger. but back then I had a dirt driveway, what leak?

[Sam Buchanan]

That's why our cars have a thingie where we can add oil!       ?

[kencombs]

9 hours ago, Dodgeb4ya said:

Rope seals do not leak small puddles if installed correctly.

The only easy and proper way to install ropes is engine out and on a stand.

The installation of rope depends on the type of rope seal design and retention in or on the engine.

I have and do use only the factory asbestos/graphite MoPar ropes.

Modern new ropes leak.

The seals need to be carefully pressed and shaped to both the crank and the retainers if used. The ropes need to have oil applied to the surface while being fitted.

As for drag of the rope on the crank...needs to be checked...only way to do it right is with just the crank in the block..no rods or timing chain connected.

Chinese finger to install...nope.

Trying to install ropes in retaining plates up through bell housing...nope.

 

 

Not ideal for sure.  But lots have been done that way, several by yours truly.  Most on Yblock Fords, notorious for rear main seal leaks (and main bearing wear).   I always 'tamped' the rope from both ends with a brass drift ground to approximate the shape of the groove in the block.  Just trying to get as much of the seal in place as possible.  Then cut the bottom a little long, bolt it together, remove and final trim.

 

Not sure I'd do it for anyone else now, but might try it on my personal driver to avoid pulling the engine, IF it was otherwise OK.

[chris 48 P15]

went to moparpro was told these will work 

will install and check for leaks

 

[James_Douglas]

Can these be replaced if need be once the engine is in the car and the bell housing in on?

 

James

[kencombs]

I'm never sure by engine stamping what main seal the block may have. My 56 has the neoprene two piece in the block, another from a 50 I think had the bolt on neoprene and another had the rope.   The bolt on only works if the block is drilled and tapped for it.  Not all are.  You should be able to tell with a flashlight and maybe mirror looking between the flywheel and block with the lower cover removed.  But the flywheel has to be removed to replace the upper half.

[Dartgame]

I used the best gasket 3675 seal on my 52. It had the two piece rope style in your last post. I was changing the clutch had the flywheel out, making this easier to get at everything. I lowered the crank by loosening all the main caps and completely removing the rear main cap. I cleaned the main cap thoroughly and flushed out the recess in the block with carb cleaner. I filled the two large back drain holes in the main cap with jb weld, allowed it to cure overnight. Cleaned the pan thoroughly and straightened the pan rail. I coated the back side of the upper seal using permatex number 2 and slid it into place, similarly coated the lower seal and slid it into place in the cap. Best recommended there be no sealant on the butt ends of the seal. I applied a small amount of  black silicone on the cap metal to metal surfaces and sent it home. NO leaks, zero. Many others have done this and have had leaks. Not sure what the difference is in what I did vs. others. Best of luck to you with however you decide to go.

Edited May 4, 2022 by Dartgame

[harmony]

On 5/2/2022 at 2:50 PM, Sam Buchanan said:

That's why our cars have a thingie where we can add oil!       ?

Dollar store aluminium cookie sheet is a good compliment to the "thingie" method as well

[greg g]

Puppy house breaking pads in addition to the cookie sheet works well for both main seal and transmission seal leaks.   When first deployed they need some scrap wood or metal weights to keep the fan from blowing them around. 

 

When I had a problem with my 46 p15 engine, I took it to a shop who's owner is a collector.  He employed a fellow who was a mechanic at the shop when it was a Desoto dealership.  He was 88 when he worked on the engine. He removed the crank, sent it across country.  It was turned, spraywelded, turned to stock spec.  Installed with fresh rope seals.  Still leaked.  My current 56 motor was checked, specd stock, installed  with new style neoprene seals.  Leaks slightly.  This engine needs a pint of oil at 500 to 600 miles.  Needs trans lube topped up once a season.  This when we put 3 to 4 thousand miles a year.  So I calling that as good as it gets, and turning a blind eye on leaks till they get worse.

Except from containing drippage in the garage.   Like old Harleys and British cars, if they aren't leaking, they may be empty...check fluid levels prior to start up.

[keithb7]

At a swamp meet in Vancouver in 2019 before “Lucky-19” there was a vendor with stacks of commercial sized backing sheets. Set up for a high volume bakery. Pretty good size. Like 3 ft x 2.5 feet or so. I bought one for my drooling flathead episodes. Think is was $15. It has a pattern of round circles reset in the base. For hamburger buns I suspect.  Catches up everything nicely.  Problem is sometimes I use it in the driveway. It also collects pollen, pine needles, pine cones, what have you, in the oil. 
 

I cannot say I haven’t driven over the edges once in a while. Its sturdy.  I works great! Swap meet seller knows his market well. 

[Bryan]

Ran across this while researching rear main seals. Are they saying a PCV system might help oil leaks from RMS?

[Bryan]

Plus they recommend offsetting the 2 piece rubber type seals so the ends  don't line up with the caps.  Rear Main Seal Replacement | Fel-Pro Gaskets (felpro.com)