All Small Six Rear main seal - Tips and Tricks

This relates to all small sixes

shreqshack

Well-known member
I pulled the transmission out of my 65 mustang (inline 6) this weekend (I am so proud of myself) to replace the clutch and found oil and sludge inside the bellhousing. I am thinking the rear main seal may need to be replaced? Unless finding oil and sludge in the BH is normal? Thoughts?

Is there any advantage to replacing the rear main seal with the transmission and flywheel off? It sounds like I will need to pull the oil pan too.

If you have any tips for changing out the rear main seal....i would be forever grateful. I am a little anxious about doing it.

Thanks to everyone....you have all been so helpful!! :)
 

wakjob

Well-known member
Supporter 2020
Yep...just did mine for the first time a few weeks ago...
Oil pan comes off...along with the rear main bearing cap.

If yours has the old style rope seal still in it...have fun.
That "sneaky Pete" tool is just about worthless...4 hours and bloody knuckles, and I was done with it.

You know that thing you pull up on in your bathroom sink that pulls the drain plug closed?
Long thin chrome rod with a big golf tee type top knob part you grab?

I found one of them at the hardware store, bent it a little, gently tapped it up and around through, and out the rope seal came...enough to grab with pliers. Helps to spin the engine from the crank bolt at the same time. Took literally 2 minutes.

P.S. I bought the Corteco 17042 neoprene seal.
 

chad

5K+
VIP
Supporter 2021
Supporter 2020
Supporter 2019
If you have any tips for changing out the rear main seal....i would be forever grateful. I am a little anxious about doing it.
there R some tips here. 2, 3 lill dabs of goo, clocking the ends...hang ona min & we'll C them posted...
Some have even gone back to the rope (if not B sure to pull the lill pin or it will pierce the neoprene 1).
 

shreqshack

Well-known member
Thanks for the responses so far. This feels like prepping for brain surgery....
Once I take the oil pan off, is there anything else I need to loosen or remove to get the rear main seal to come out??
Is there any advantage to doing this with the transmission and flywheel off??
 

chad

5K+
VIP
Supporter 2021
Supporter 2020
Supporter 2019
have u used our search function.
most of these proceedures R repeated over and over here
 

bubba22349

Top Poster
Staff member
VIP
Supporter 2021
Supporter 2019
REDLINE 10K
Thanks for the responses so far. This feels like prepping for brain surgery....
Once I take the oil pan off, is there anything else I need to loosen or remove to get the rear main seal to come out??
Is there any advantage to doing this with the transmission and flywheel off??
Directions are located in severial older posts so this is going to be a bit abbreviated. Yes with a manual trans it will need to be pulled out to drop the crankshaft a little bit. Flywheel and clutch could be left on the crankshaft but it will be easier without the extra weight. An Auto Trans car can get by with the trans in place just unbolt the torque converter from the flex plate and side it back towards the transmission all the way so the torque converters studs will clear the flex plate.

After that unbolt the rear main cap and remove it, next loosen up the other main caps closest to rear main will need to be looser and as you go forward towards the front of the engine the main cap bolts don't need to be as loose this is so the crankshaft can drop down some at the rear to get the old seal out and in order to install a new rope seal. Replacement of the seal if your using a neoprene seal in place of a rope you will need to remove the nail like pin. Clock the neoprene seal and use a dab of RTB check the older posts for all the details on best methods. To button it back up Start by pushing crankshaft back up into the main bearings and snug up the main cap bolts Install the rear main cap and then torque all your main cap bolts to spec. Reinstall the oil pan. Reinstall your trans again, and your done
 

B RON CO

1K+
VIP
Supporter 2021
Supporter 2018
Hi, if you knew of half the issues with rear main seals you would rather perform brain surgery!
My advice is to study a Ford or Chilton's Manual and learn the steps involved.
The job is not self explanatory.
Good luck
 

twodogs

Active member
Supporter 2021
I pulled the transmission out of my 65 mustang (inline 6) this weekend (I am so proud of myself) to replace the clutch and found oil and sludge inside the bellhousing. I am thinking the rear main seal may need to be replaced? Unless finding oil and sludge in the BH is normal? Thoughts?

Is there any advantage to replacing the rear main seal with the transmission and flywheel off? It sounds like I will need to pull the oil pan too.

If you have any tips for changing out the rear main seal....i would be forever grateful. I am a little anxious about doing it.

Thanks to everyone....you have all been so helpful!! :)
Oil and sludge inside the bellhousing isn't normal. I had the same thing on my 200 cid in my Bronco and it destroyed my clutch. I replaced the clutch and rear main seal on mine, buuuuuuuuut, I pulled the engine to do it. I decided that I'd rather work with it on an engine stand than while laying on my back. I also took the time while it was out to clean up the engine bay, and do a bunch of other miscellaneous engine work (replaced all the freeze plugs, new timing chain, water pump, thermostat, new rod bearings, etc.). I suffer from "as long as I'm this far," syndrome.

The others are right. Search on here, and then read and re-read a Chilton's or Ford shop manual. I read both.
 

chad

5K+
VIP
Supporter 2021
Supporter 2020
Supporter 2019
10 daze, awright mate?
Find the other threads w/more detail? get da littrature? push it over a cliff & now headache free?
 
Last edited:

bubba22349

Top Poster
Staff member
VIP
Supporter 2021
Supporter 2019
REDLINE 10K
Adistionally there is also a front seal on a manual transmissions input shaft, it's inside front cover that the throwout bearing slides on. If the oil and sludge is of a much heavier viscosity / weight and it also has a different smell to it than engine oil does.
 

shreqshack

Well-known member
I need some help. I am having difficulty getting the rear main seal. I pulled the oil pan, took off the end cap and loosened other bolts in the crack shaft. I have tried using some thin metal instruments to poke the old seal out and it’s not coming out. I think the problem is that the existing seal is not rigid. It may be a rope seal. Any suggestions. I really do not want to take the motor apart any further. ... I’m guessing that is the next step. Ugh!!!
 

bubba22349

Top Poster
Staff member
VIP
Supporter 2021
Supporter 2019
REDLINE 10K
Did you pull down on the crankshaft some? Try turning a metal screw into the rope seal then grab that with some pliers and pull on lt.
 

shreqshack

Well-known member
Directions are located in severial older posts so this is going to be a bit abbreviated. Yes with a manual trans it will need to be pulled out to drop the crankshaft a little bit. Flywheel and clutch could be left on the crankshaft but it will be easier without the extra weight. An Auto Trans car can get by with the trans in place just unbolt the torque converter from the flex plate and side it back towards the transmission all the way so the torque converters studs will clear the flex plate.

After that unbolt the rear main cap and remove, next loosen up the other main caps closest to rear main will need to be looser and as you go forward towards the front of the engine the main cap bolts don't need to be quite as loose this is so the crankshaft can drop down some at the rear to get the old seal out and in order to install a new rope seal. Replacement of the seal if your using a neoprene seal in place of a rope you also need to remove the nail like pin. Clock the neoprene seal and use a dab of RTB check the older posts for all the details on best methods. To button it back up Start by pushing crankshaft back up into the main bearings and snug up the main cap bolts Install the rear main cap and then torque all your main cap bolts to spec. Reinstall the oil pan. Reinstall your trans again, and your done.
 

shreqshack

Well-known member
I have a couple questions -- I am planning to put the new main seals in tonight and tightening back up the crankshaft bolts tonight. When I look at the crankshaft now, it does not appear to be hanging down at all (visually). However, is there anything I need to do to make sure that the crankshaft is tightened back in the right position before I tighten it back up?
 

MustangDadDrake

Well-known member
Supporter 2021
When I loosened the crankshaft I too did not notice any visible drop and since I was messing with the crank shaft I too was afraid id screw something up. I went ahead and tried to get the seal in anyway. I was able to by putting a lot of oil on it and very slowly sliding it up there. I did buy two seals because the first time I rushed it and shaved some of the seal off, just to be safe a bought another one and tried again.
 

wsa111

Distributor Recurving.
Staff member
VIP
Approved Vendor
Supporter 2018
Go with the neoprene seal. The rope seal is ancient technology.
Make sure you remove the pointed pin in the rear main cap. The pin is only used with the rope seal.
When installing the seal make sure the butting ends are at 4:00 on one side & 10:00 on the other side.
Toyota or Lexus sealer FIPG is the best to dab on both ends of the seal. Grey permatex is an ok second choice. Make sure you also put a small amount of sealer on the edge where the rear main cap sits in the block on both sides, also put a very thin layer of sealant at the back of the rear main cap from the seal to the end of the main cap on both sides. That will prevent seepage past the machined surfaces where the rear main cap seat into the block.
Make sure the seal & crankshaft journal have a liberal amount of lube to prevent a dry start.
Give the sealer at least an hour to set up before you rotate the crankshaft.
How dry i am. No runs, drips if done right.
 

chad

5K+
VIP
Supporter 2021
Supporter 2020
Supporter 2019
this must B ina Sticky by now, repeated so often.
Post 18 is the read deal, seal of approval by bubs too.

"...With a manual trans it will need to be pulled out to drop the crankshaft a little bit. Flywheel and clutch could be left on the crankshaft but it will be easier without the extra weight. An Auto Trans car can get by with the trans in place just unbolt the torque converter grom the flex plate and side it back towards the transmission all the way so the torque converters studs will clear the flex plate.

After that unbolt the rear main cap and remove, next loosen up the other main caps closest to rear main will need to be looser and as you go forward towards the front of the engine main cap bolts doesn’t need to be as loose this is so the crankshaft can drop down some at the rear to get the old seal out and in order to install a new rope seal. Replace the seal if your using a neoprene seal in place of a rope you need to remove the nail like pin. Clock the neoprene seal and use a dab of RTB check the older posts for all the details on best methods. To botton it back up Start by pushing crankshaft back up into the main bearings and snug up the main cap bolts Install the rear main cap and then torque all your main cap bolts to spec. Reinstall the oil pan. Reinstall your trans again, and your done..."
"...Make sure you remove the pointed pin in the rear main cap if ditchin the rope seal. The pin is only used with the rope seal.
When installing the seal make sure the butting ends are at 4:00 on one side & 10:00 on the other side.
Toyota or Lexus sealer FIPG is the best to dab on both ends of the seal. Grey permatex is an ok second choice. Make sure you also put a small amount of sealer on the edge where the rear main cap sits in the block on both sides, also put a very thin layer of sealant at the back of the rear main cap from the seal to the end of the main cap on both sides. That will prevent seepage past the machined surfaces where the rear main cap seat into the block.
Make sure the seal & crankshaft journal have a liberal amount of lube to prevent a dry start.
Give the sealer at least an hour to set up before you rotate the crankshaft..."
 

bubba22349

Top Poster
Staff member
VIP
Supporter 2021
Supporter 2019
REDLINE 10K
I have a couple questions -- I am planning to put the new main seals in tonight and tightening back up the crankshaft bolts tonight. When I look at the crankshaft now, it does not appear to be hanging down at all (visually). However, is there anything I need to do to make sure that the crankshaft is tightened back in the right position before I tighten it back up?
You didn’t state which kind of seal you will be using so this is for both seal types. Yes the crankshaft is not going to be hanging down any! I guess i forgot one important thing in the instructions and this only applies when your doing this type seal replacement with the engine still in the cars chassis. That is that the crankshaft just isn’t going to drop down much if any on its own. You will need to really pull on it or use a pry bar at the rear crankshaft flange to get it to move don’t worry with all the other main caps loose in place its not going to fall out. This part is important to do and might explain why some have had trouble in the past when switching over to using one of the neoprene type rear seals if you don’t provide some extra clearance between the crankshafts rear main and the block for the new seal to be able to slide in easily it could get damaged. And you will need even more rear main clearance to be able to get a new rope seal back into the short block. So be sure to do it right the first time and no cutting of any corners and you will have a successful rear main seal replacement. Best of luck
 
Top