rear oil seal on a 3406e engine

rear oil seal on a 3406e engine

Posted in the Caterpillar Forum


Monroeville, AL

#1 Aug 8, 2010
i have a problem i have a 3406e cat engine the seal i am getting from the cat part house has a metal ring on the inside of the seal
i have had 2 shops put this seal in and every one has removed that inside ring and it starts leaking the 2 shop forman keep saying that is has to be remove after installing it. that ring is a there to help install the seal. now i have heard someone say its a wear ring and that it stays on can anybody help me figure this out they are installing a new one again
on the inside of the ring it has install dry and it has engine rotate in clock wise so does the ring come out or does it stay on
thanks for your help

Since: Jul 08

Location hidden

#2 Aug 8, 2010
both the front and rear crankchaft seals are meant to be installed with the inner ring, which indeed is a wear sleeve protecting the crankshaft from grooving. if someone has gone and replaced only the seal itsel that means the person cannot read the instruction that come along with the package of the new seal group. the seals that are available now are universally fit for all 3400-family cat engines and do not have a separatable wear sleeve, thus making it even more clear that the seal group should only be installed as a unit, not separately. the current seal is a hydrodynamic seal and does not function with the older generation wear sleeve, especially if the old sleeve has a worn groove from the old lip-type seal. also it is nearly impossible to remove the wear sleeve from these current seals without destroying the hydrodynamic seal itself.

these seals are meant to be installed with special tooling and cannot be installed separately or onto a housing thats off the engine. also removing the wear sleeve requires special tooling.

the rear seal should be blue or purple coloured and must have a counter-clockwise rotation cymbol, hence the engine rotation is counter-clockwise.
the front seal should be green coloured and must have a clockwise rotation cymbol. if these are mixed they will definately leak as the hydrodynamic function will be inverted if the shaft rotates in the wrong direction.

ask for more info.

Potomac, MD

#3 Dec 13, 2010
how does the rear main seal tool looks like?
john H

Highgate Hill, Australia

#4 Sep 16, 2012
So the front crank has a steel wear sleeve on it that must be removed so the new integrated seal can be fitted ?

“Cat & Cummins ECM programs”

Since: Jun 12

Marion, IN

#5 Sep 19, 2012
john H wrote:
So the front crank has a steel wear sleeve on it that must be removed so the new integrated seal can be fitted ?
Yes it does. I normally "break-up" the rubber seal in the middle with a flat screwdriver, then I use the screwdriver to "pry" the outer ring from the front cover. I use a small 3-jaw puller with thin arms to pull the wear-ring fom the crank.

The front and rear seals are both removed & installed the same way, make sure you get the right seal (rotation arrow on front). The same tool installs both seals!

Talladega, AL

#6 Jun 5, 2014
I have a question. Is that seal the only place between the motor and tranny that will leak? I've never been in that area before and experiencing oil coming out of the Inspection plate and crack between the motor and transmission.

Antioch, TN

#7 Jun 8, 2014

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