Slantsix64
Well-Known Member
Try using thicker oil.
Has anyone tried Blue Devil Rear Main Seal Stop Leak?
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Slantsix64
Well-Known Member
I seen, a slant six drip oil while it was on from the rear main seal, we used blue devil oil stop not rear main seal one. Poured it in let it idle for an hour it was now pissing it out you could tell it was the additive cause difference in color, 30 miles later, there is no leak at all.
I knew a mechanic who would pour a quarter of that stuff in his rebuilt motors, and also the bars leak coolant one just a little for that cheap insurance. lol
Dave999
Well-Known Member
Rope seal needs a good knurl on the crank. and fitting a new rope seal and actually have it work is a time consuming engine out job.
Most modern rope lacks the asbestos of the orginal and they are just not very good. modern is glass fibre and graphite no asbestos fibre to keep it working, which is a shame this wasn't the truly dangerouse stuff...
most modern stuff is sold at $30-50 for 2 short lengths of rope. the sellers know they have you by the conkers. you will find good OLD style asbestos rope in NOS ferguson tractor packing... ebay, just nobody mentions that......
Most modern grey black graphite impregnated rope seal is actually just industrial gland packing rope off a big roll cut and packaged and sold at a high price.
you can pay somone like Bestgasket $50 for it of you can buy
this kinda stuff in 3 foot lengths suggest 10 mm or 12 mm squre section is about right. too fat isn't a problem crank is gonna be 1 foot bar, 1 hand stiff anyway when installed. lube it up.
Gland packing Graphite shaft and stem usage (various sizes) | eBay
rubber seals can be fitted without removing the crank if you can get the sump off
However some caveats
1) if the motor was rope and you are going rubber, the housing will not have been ground close enough to concentric with the seal surface in some cases...Rope deforms to the crank rubber stays the shape of the housing.
even worse if the case has been align bored. they don't align bore the seal housing. so you end up with the rubber seal squashed too tight at the top, wears out, and not enough at the bottom. strip of copper or brass or shim stock steel under the seal on the loose side, burried in silcone to shim it can help.
2) if the motor was rubber seal, ideally you glue the seal in with silicone or anerobic sealer and it should be offset a few thou from tha case/cap parting line. doing this without removing the crank, under the car with oil dripping is no fun.
you have to try to wind in the seal by turning the crank. easier to take it out
3) you can, if you can find a shop that will do it get your seal surface re knurled so you can use rope again. some will not do this. stateing that the crank will have case hardend over its life and you will create cracks. they won't want the cost of a new crank on their hands.
A rope seal if installed properly works really really well, no issues with housing concentricity etc.
alternatives or stuff you could do if you can be bothered
mancini racing do rear main seal leak buster bearings. you can't get em for a slant but anyone with a dremel can make one
see here
Mancini Racing Anti Leak Rear Main Bearing
The aim is to bias the oil flow in the rear bearing so the oil wedge favours an exit on the front side. seal will still be lubed with mist. it just won'tbe being hosed down all the time.
i find 2 lines in same direction based on crank rotation to drive oil out does no harm why they have done 2 in oposite directions i don't know.
other options
another issue with 2 part rubber seals is the split line in them, the lip puckers up at the join in 2 places unless you are very lucky.
Now I don't have a slant but i estimate the seal housing with seal inner diameter of approx 2.750" i might be wrong, i apologise if i am, i don't have manual for a slanter
so
https://butlerperformance.com/i-244...-main-seal-301-326-350-389-400-bop-rms18.html
is a 1 piece rear main seal for 3 inch seal surface for a pontiac made by BOP engineering. (installation instruction for pontiac at bop engineering site) it has a wire spring steel centre and is double lipped with an appropriate knurled profile on the lips to fire oil back in to the sump, if you install it the correct way round.
it has 1 gap where you cut the seal to fit it. this goes to the top when installed
in theory you could cut it pull back the rubber, trim the spring and rubber to appropriate size for a slant and join the ends with super glue and silicone.
With just 1/4 inch difference puckering of the lip should be negligible.
its an option i will try on my 2.5 inch Journal 6 at some point but it is more likely to work on the bigger slant seal area provided it has no knurl.
i spoke to BOP Engineering about 10 years ago suggesting he tool up 2.5 2.75 sizes as well to cover some mopar applications... he didn't want to take the risk having no mopar motors/race cars to try them out in.
rope seal install video. yes its for a holden. but good workman like attitude and care for the details, makes this a master class from COME racing
Dave
Most modern rope lacks the asbestos of the orginal and they are just not very good. modern is glass fibre and graphite no asbestos fibre to keep it working, which is a shame this wasn't the truly dangerouse stuff...
most modern stuff is sold at $30-50 for 2 short lengths of rope. the sellers know they have you by the conkers. you will find good OLD style asbestos rope in NOS ferguson tractor packing... ebay, just nobody mentions that......
Most modern grey black graphite impregnated rope seal is actually just industrial gland packing rope off a big roll cut and packaged and sold at a high price.
you can pay somone like Bestgasket $50 for it of you can buy
this kinda stuff in 3 foot lengths suggest 10 mm or 12 mm squre section is about right. too fat isn't a problem crank is gonna be 1 foot bar, 1 hand stiff anyway when installed. lube it up.
Gland packing Graphite shaft and stem usage (various sizes) | eBay
- Pressure Rating:400 Bar (no problem)
- Rotary Speed: 20m/s i.e good enough for the speed of your crank upto 5500 rpm 6000 rpm would be 22m/s with a seal circumferance of about 8.5 inch
- pH Range: 0-14 (no worries)
- Temp. Range (Inert ATM): -200°C to +3000°C (not relevant)
- Temp. Range (In Air): -220/+550°C (650° with steam) ok
rubber seals can be fitted without removing the crank if you can get the sump off
However some caveats
1) if the motor was rope and you are going rubber, the housing will not have been ground close enough to concentric with the seal surface in some cases...Rope deforms to the crank rubber stays the shape of the housing.
even worse if the case has been align bored. they don't align bore the seal housing. so you end up with the rubber seal squashed too tight at the top, wears out, and not enough at the bottom. strip of copper or brass or shim stock steel under the seal on the loose side, burried in silcone to shim it can help.
2) if the motor was rubber seal, ideally you glue the seal in with silicone or anerobic sealer and it should be offset a few thou from tha case/cap parting line. doing this without removing the crank, under the car with oil dripping is no fun.
you have to try to wind in the seal by turning the crank. easier to take it out
3) you can, if you can find a shop that will do it get your seal surface re knurled so you can use rope again. some will not do this. stateing that the crank will have case hardend over its life and you will create cracks. they won't want the cost of a new crank on their hands.
A rope seal if installed properly works really really well, no issues with housing concentricity etc.
alternatives or stuff you could do if you can be bothered
mancini racing do rear main seal leak buster bearings. you can't get em for a slant but anyone with a dremel can make one
see here
Mancini Racing Anti Leak Rear Main Bearing
The aim is to bias the oil flow in the rear bearing so the oil wedge favours an exit on the front side. seal will still be lubed with mist. it just won'tbe being hosed down all the time.
i find 2 lines in same direction based on crank rotation to drive oil out does no harm why they have done 2 in oposite directions i don't know.
other options
another issue with 2 part rubber seals is the split line in them, the lip puckers up at the join in 2 places unless you are very lucky.
Now I don't have a slant but i estimate the seal housing with seal inner diameter of approx 2.750" i might be wrong, i apologise if i am, i don't have manual for a slanter
so
https://butlerperformance.com/i-244...-main-seal-301-326-350-389-400-bop-rms18.html
is a 1 piece rear main seal for 3 inch seal surface for a pontiac made by BOP engineering. (installation instruction for pontiac at bop engineering site) it has a wire spring steel centre and is double lipped with an appropriate knurled profile on the lips to fire oil back in to the sump, if you install it the correct way round.
it has 1 gap where you cut the seal to fit it. this goes to the top when installed
in theory you could cut it pull back the rubber, trim the spring and rubber to appropriate size for a slant and join the ends with super glue and silicone.
With just 1/4 inch difference puckering of the lip should be negligible.
its an option i will try on my 2.5 inch Journal 6 at some point but it is more likely to work on the bigger slant seal area provided it has no knurl.
i spoke to BOP Engineering about 10 years ago suggesting he tool up 2.5 2.75 sizes as well to cover some mopar applications... he didn't want to take the risk having no mopar motors/race cars to try them out in.
rope seal install video. yes its for a holden. but good workman like attitude and care for the details, makes this a master class from COME racing
Dave
gregcon
Well-Known Member
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I believe all of those miracles in a can are just snake oil. That's why I rely on 2 cups of oatmeal to fix any leak...it's what the true professionals rely on. None of that maple and brown sugar crap either - just plain oatmeal with a few raisins if you must.
Except I don't think the BBs use those little side wing pieces, though it's been a while since I have worked on a BB engine
K.O. SWINGER
Meeting in the alley since 1976
If you have a gravel parking lot and don't mind checking the oil all the time go for it. Not for me though if you lose a motor to a crank seal one time that'll cure you. Don't ask me how I know, or do.
Frank Mopar
Well-Known Member
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