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Cummins QSB 4.5 RGT/NEF 445t/m2 Rear Main Seal (Again)


Cdfarabaugh

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Awhile ago I had a post about this engine and some rear main seal woes.  Thought it was figured out, installed another one with what I determined the proper tooling was and no go again.  This time we smoked the crankcase with an evap tester and applied some positive pressure before removing the old seal and it would not leak one bit like that.  No leaks showed up elsewhere.  Checked crankshaft end play: it is in specification.  Checked flywheel housing runout and we came up with .010 of runout.  I can not find a specification on that but that number does not alarm me. 

Now, for the next step I considered trying a different style of seal.  The seal I used (and is called for in parts) was a 4890833 unitized seal design.  According to quickserve these engines could use that or a lip seal style.  I purchased a 3926126 seal kit with the wear sleeve.  The ID of the seal is correct, but the OD is a bit too small........scratch that idea. 

Now, pondering the next step I read Quickserve and found that they talk about a "spacer" to use with a unitized seal.  Ill be DANGED if I can find any of these seals that come with a spacer.  I am using the proper tooling to install.  The last seal went in nicely.  

I cant help but think what is going on is the 2 pieces of the seal are being "jammed" together as that installer has a flat face.  Any other 2 piece style seal installer I used has a "step" usually machined in to push the inner and outer portion of the seal separately.  The more I think it makes sense with whats going on here and probably is why that spacer is mentioned. 

The other theory is not installing the seal so deep that the tool bottoms out against the housing (even though thats in the instructions) 

Hopefully someone else can shed some light on my theory and if I am nuts at all.   

seal 1.PNG

seal 2.PNG

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The tool should have a step so that the inner and outer part of the seal remain in position to each other

The plastic shim usually comes with a new seal -- and has the step made into it, so you can use a "flat" tool
Also pushes the seal into the housing just past the counter bore

Yeah, cant just jamb the seal parts together -- would create a lot of heat in the seal

Pop the old seal apart and you will see that it is just a lip seal with the inner sleeve made into one housing
the two parts should not be rubbing on each other -- only the seal lip on the sleeve

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22 hours ago, Cdfarabaugh said:

Awhile ago I had a post about this engine and some rear main seal woes.  Thought it was figured out, installed another one with what I determined the proper tooling was and no go again.  This time we smoked the crankcase with an evap tester and applied some positive pressure before removing the old seal and it would not leak one bit like that.  No leaks showed up elsewhere.  Checked crankshaft end play: it is in specification.  Checked flywheel housing runout and we came up with .010 of runout.  I can not find a specification on that but that number does not alarm me. 

Now, for the next step I considered trying a different style of seal.  The seal I used (and is called for in parts) was a 4890833 unitized seal design.  According to quickserve these engines could use that or a lip seal style.  I purchased a 3926126 seal kit with the wear sleeve.  The ID of the seal is correct, but the OD is a bit too small........scratch that idea. 

Now, pondering the next step I read Quickserve and found that they talk about a "spacer" to use with a unitized seal.  Ill be DANGED if I can find any of these seals that come with a spacer.  I am using the proper tooling to install.  The last seal went in nicely.  

I cant help but think what is going on is the 2 pieces of the seal are being "jammed" together as that installer has a flat face.  Any other 2 piece style seal installer I used has a "step" usually machined in to push the inner and outer portion of the seal separately.  The more I think it makes sense with whats going on here and probably is why that spacer is mentioned. 

The other theory is not installing the seal so deep that the tool bottoms out against the housing (even though thats in the instructions) 

Hopefully someone else can shed some light on my theory and if I am nuts at all.   

seal 1.PNG

seal 2.PNG

Can you post a picture of the seal you are installing. Is it a Teflon lip seal metal outside usually red with yellow sealing lip with wear ring or is it one of the newer styles with the double lipped wear ring and rubberized outside. You need the spaper with first seal not the second type.

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54 minutes ago, dale560 said:

Can you post a picture of the seal you are installing. Is it a Teflon lip seal metal outside usually red with yellow sealing lip with wear ring or is it one of the newer styles with the double lipped wear ring and rubberized outside. You need the spaper with first seal not the second type.

This style

114890833.jpg

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23 minutes ago, HydroTek said:

Yeah, that seal does look "flat" to me also

Been too long since I have replaced one on that engine to remember the exact shape of the seal and tool

It is flat, but as you alluded to it seems as if the outer metal shell and the inner black piece run awfully tight together if pushed flush.  

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I made a spacer ring for our Cummins "B" series seal installer to install rear mains like you have pictured. The spacer has a counter step on it that centers seal in the inner wear ring. If inner rings floats .060 then to center seal in wear ring, step needs to be .030

We use it on Case skid steers with NEF engines as well as the Maxxum series tractor and their NH cousins.   

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On 10/16/2023 at 5:58 AM, CIHTECH said:

I made a spacer ring for our Cummins "B" series seal installer to install rear mains like you have pictured. The spacer has a counter step on it that centers seal in the inner wear ring. If inner rings floats .060 then to center seal in wear ring, step needs to be .030

We use it on Case skid steers with NEF engines as well as the Maxxum series tractor and their NH cousins.   

@HydroTek @dale560. Going to try this to space the outer and inner part out by .040"

20231019_114522.jpg

20231019_114507.jpg

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