Thread: 300tdi - best rear main seal?

Something I learnt the hard way after running twice having R380's stuff themselves chewing up front gears from lack of oil. Seems they may blow it out the rear seal a lot faster if the breather tube is blocked and the gearbox gets hot from running for more than a short time. Air pressure is then added to the pressurised oil in the rear bearing in front of the seal. This type of leak does not leave much tell tale oil under vehicle when it is parked because it would mainly blow out at high speed and then wind carries it rearward. So evidence of this oil is largely on diff housing.

After realising that problem may have been caused or exacerbated by a blocked breather, I pulled it off and tried blowing through it from gearbox end. Seemed completely blocked. Note breather on Defender is a black plastic tube which has been bent into a semicircle at the end that hangs on the rear of tappet cover on motor. Initially I thought blockage may have been due some species of insect that builds nests in suitable sized holes it can find. Tried pushing a length of thin wire through from gearbox end. (Actually soft black oxy welding filler rod) With a hard push it emerged from the engine end but no evidence of a 'wog' nest or whatever. The non self straightening bend in the plastic tube was obviously created with the help of some heat. In the process apparently caused somewhere in this section of the tube to stick itself closed. May have been not quite completely closed most of its life but sealed after some additional inadvertent heat and /or flexing of the tube.

it appear another contributing cause to rear seal oil leaks may be the seal not quite in the correct position relative to the collar on the output shaft it runs on. Need to be very careful the seal is installed straight and also not pressed in too far, as no shoulder to stop it. Almost certainly to fix mistake here would need to destroy seal to get it out and then replace with another new one.

I agree with the possibility that there may be better seals available for this application than the standard ones commonly used. Would like to get on if/ when I find where. Hopefully will be a reply to the original question that started this thread.

Which seal did you use - Genuine?

Did you replace anything else while the engine was out?

Originally Posted by Ranga

Replaced the rear main seal yesterday (engine out), and sure enough after test driving it today, it's leaking. I've heard this is a (very annoying) common occurrence.

OUCH!! Mate your taking that well. I would be swinging from the rafters in a fit of rage!
Particularly given i just changed out a rear main seal a few days ago. (v8 though)
I hope you sort it out.

was there a wear ring on the crank face? sometimes fitting a new seal lip on the same spot can cause a leak.

Turner Engineering in the UK. They manufacture their own seals that are proven better than genuine. A bit more expensive but well worth it. Super fast delivery to. I ordered complete engine rebuild parts on a Monday and had them by Thursday. They are thw best by far.

LUF100430 Rear Oil Seal

LesH.

That's good to know - thanks Les