Unimog hub temperatures

[CragMog]

If it's the U1300L portals then both front and rear portals migrate oil due to high speed driving. On the fronts, I'm not even sure it takes very long for the migration to occur so don't assume it's distance related. The rear portals lose oil for two reasons, one is migration through the vent, the other is that the inner seal is damaged. These portals were not designed for 100kmph and bigger tyres, but that's how we choose to drive our trucks so all of us U1300L owners need to find a solution. The early U1550L/U1350L and SEE portals are roughly the same casings, but they have much stronger bearings. The lower, outer bearing goes from 11mm to 14mm requiring a different gear and wear ring. The lower inner and upper bearings go from ball bearings to better quality roller bearings. These are worthwhile modifications.

The VGE 3.0 product is a proven solution and keeps the 300ml inside the portal where it's most needed. Jostt's reservoirs are very interesting. When the gears spin and lift the oil, is there any way of determining how much stays in the portal and how much in the reservoir?

I drain my portals every time I change the engine oil, so every 8,000kms. That's how I picked up the LHS rear failure, recently the RHS rear failure and the beginning of the RHS front failure. The LHS front is leaking at the inner seal. For the U1300L portals we only need 1.2l of oil in total so price isn't a barrier. What is the worlds best hypoid, low foaming, GL5, final drive oil available that can withstand constant high temperature running?

Good oil, HD bearings, resolved venting, new seals and regular servicing should do the trick........I hope!

 

[charlieaarons]

Hi Charlie, what sensors does the Atlas system come with? I have a Blue Sea systems temperature monitor and I used epoxy glue to stick on the sensor to the portal casing. I had the rear brake pad get stuck, causimg the temperature to risequite a bit, got to 70 Deg C by the time I found a safe place to pull over. Normal temps are about 20 Deg C above ambient aand the front ones are normally around ambient unless I've been braking.

View attachment 453977

Thermocouples that go into the drain plug holes.

 

[Jostt]

Some more km's on the test, after 3 hours non stop on the highway, whit a very hard temperatures, the summer is caming very heavy, 35 c° degrees whit hi humidity, the front portals keep almost cold...the Main problem is the rear diff....a bit hot
The rear portals were arround 56-60 degrees, under 30 more than ambiente, thats normal , I think, the front are more or less 10 degrees less, so I think is ok, no leacks on the seals

 

[Wyuna]

good to see that there are no leaks.

Any plans to find a way to cool the rear diff.

 

[Jostt]

For the rear diff just to stop and take a cool bier....

 

[Jostt]

I was not convince about the temperature in the front disk and center hub , and for my surprise the two pistón on the front calipers were stack , so its make step by step hot all this parts, so before holidays I Will replace all the seals

 

[Jostt]

One day to rebuild the 4 front calipers , two of theme whit some rust on the pistons, I think they are still ok because it is after the internal seal ...so clean and polish, I think It Will solve the problem of hi temp on the disk, because by the rust it was imposible for the pistón to go fully back when release the pedal, thats why small fricction warms the rotor.

 

[LostInTheWorld]

I'm glad you found the problem.

Thanks for posting photos of the process. It's always nice to have reference images.

Michael

 

[Jostt]

Just in case you think in rebuild the calipers on future, the only detail is to take care whit the two orings betwen the two parts of the calipers, Mercedes do not sale as a spare, there is two each caliper, the other parts Mercedes sale as a kit, any info you need let me know, I hope there was the problem , because Im coming crazy....

 

[LostInTheWorld]

Cool, thanks for the info on the o-rings. I might get some and carry them as spares.

Michael

 

[Jostt]

I can not be more fustrated this morning....after 40 km the problem is still there....so next is the hidraulic pump....the brakes take again hi temperature after few km

 

[Jostt]

Im cheking now the neumatic valve on the pedal, because maybe when I release the pedal it is still sending some amount of air in the brakes, thats why it has some brake presure....if not I Will check boster and hidraulic pump....no more things....

 

[Iain_U1250]

have you replaced the brake hose/lines, sometimes a squashed line or old hose is restricted. It will be ok when pushing the brakes, but the flow might not release if the line is partially blocked or squashed. All the lines on my truck were in very bad conditon, so I replaced them all. Front and rear brakes were dragging on mine when I got the truck

 

[Jostt]

I have all the brake lines ordered, I Will replace it first , maybe is this, what is true is the system is to complicated to be save....now I understsnd why the people complain about mix systems, thanks Ian

 

[Jostt]

Long history ....after many hours I found the real reason for the brakes failure, there was not only one , but this week I arready made a trip and now I can say it is solve.....there is a valvle in this truck to compensate the extra load on the rear axle , it seems like it can not make any interference on the front axle brakes , but it is not like this, when this valvle fail , can make a disaster on front , like myone, but also the neumatic boster on the hidraulic pump was dirty....no sorry dirty is another think...any way, after last month I understsnd how important is the service on the brakes for this truck , next step I Will add a dryer on the neumatic system....