1998 V70R AWD Angle Gear cooks the oil

gmtgmt · Post by **gmtgmt** » 15 Jun 2012, 16:23

1998 V70R AWD

After a 15miles drive it cooks the oil in the angle gear.
Allready mounted a New OEM Volvo Unit. no change.

Im removing the drive shaft tommrow and will see if stops this.

Does anyone have an idea on what the problem is ?

It has 4 of the same size tires...

Post by **MoVolvos** » 15 Jun 2012, 16:48

gmtgmt wrote:1998 V70R AWD
After a 15miles drive it cooks the oil in the angle gear.
Allready mounted a New OEM Volvo Unit. no change.

Do you mean after a complete fluid change of the Gear Oil 75-90W?
Can you describe Cooks or perhaps Cooked Oil?
http://www.volvoxc.com/forums/archive/i ... 10291.html

Blessings,
BKM
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gmtgmt · Post by **gmtgmt** » 15 Jun 2012, 17:09

yeah sorry, i have tired 4 times to make a thread and made a few long post but every time i click submit i get thrown off and need to log on

The gear oil Heats up and boils? it smells very bad inside the car through the AC and with I look at the output for the right side drive shaft steam are comming out. It dosent have any noise at all or anything only when i let it cool of for a few min and drove again but thats was proberly just because the oil was degrated now. When i removed the filling plug it squirted all over the floor with exemely hot oil

I have Mobil 75W90 Gear oil i will fill it up with tommrow. but it was with OEM volvo oil in it.

Post by **jimmy57** » 15 Jun 2012, 18:41

Tires not being the same size or a locked up viscous coupling, or a bit of both will cause this. The viscous coupling is supposed to allow some speed difference between the prop shaft and the rear diff . If it doesn't the stress is on the angle gear. If tires hve a circumference that is too greatly different (more then 6-7 mm) it is too much. The larger need to be on front when there is any measureable difference.

Post by **MoVolvos** » 15 Jun 2012, 19:32

gmtgmt wrote: The gear oil Heats up and boils?... I look at the output for the right side drive shaft steam are comming out.

I have Mobil 75W90 Gear oil i will fill it up with tommrow. but it was with OEM volvo oil in it.

According to this link boiling can also indicate Low Fluid (Leak)? You may want to clean out the area before working on it. If it does not boil after changing to the Mobil then look to see where it has gone perhaps the seal on the right side drive shaft where the steam was coming out.
http://www.bobistheoilguy.com/forums/ub ... er=2087437

Blessings,
BKM
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Post by **anjill182** » 15 Jun 2012, 20:46

Jimmy,
Report this postReply with quoteRe: AWD Tolerances
by jimmy57 » 07 May 2012, 17:41

smaller circumference on the back. There is a very little tolerance for the front being larger as the rear having slower rotational speed is the situation the system is designed "lock" in. There is a one way clutch that is part of the viscous coupling and it allows rear to overrun the front above approx 30 MPH.
FOr low speed driving there would have to be some limit to the size difference since the stress would still be there. 3/4 of inch I know was no problem for set I had on my car.
There was no ill effects when using those tires until I replaced them.

This post conflicts with previous posts by you. Which is correct?

Post by **jimmy57** » 15 Jun 2012, 20:58

I corrected it.
Thanks for the catch. It is larger on front. The rear needs to overspeed the front if there is a size difference as explained in the other post. This will occur with the back as smaller circumference as a tires with 54.2 inch circ. will go more revolutions than one with 54.9 inch circ.

Post by **JDS60R** » 15 Jun 2012, 21:46

Perhaps you have a concern with the breather and the oil level.

If I understand your second post correctly when you remove the "fill" plug you have lots of oil coming out.(Some should as oil expands slightly with heat - but not as much as I think you are describing )

I hope Jimmy can chime in but I believe the update was to fill it cold and then remove some. My thoughts are that it is overfilled and coming out the vent onto the exhaust or engine. This would cause the burning sulfur smell common in any GL-5 lubricant.

You may wish to wash the areas down first to remove any old oil and then refill it to below the fill line or whatever level Jimmy suggests.

Hope that helps

Post by **jimmy57** » 15 Jun 2012, 22:08

The fill level is 3-4 mm below the fill plug.
I think he is describing something I have seen a few times. with stress from mismatched tires the angle gear can get hot enough to make the oil smoke. I measured a surface temp on one of 340 degrees. Usually these are the ones that end up with an angle gear failed because the gear oil getting cooked like that soon fails bearings and the gear teeth wear from oil with little lubrication properties.

gmtgmt · Post by **gmtgmt** » 16 Jun 2012, 02:59

jimmy57 wrote:The fill level is 3-4 mm below the fill plug.
I think he is describing something I have seen a few times. with stress from mismatched tires the angle gear can get hot enough to make the oil smoke. I measured a surface temp on one of 340 degrees. Usually these are the ones that end up with an angle gear because the gear oil getting cooked like that soon fails bearings and gear teeth wear from oil with little lubrication properties.

Exacly what i mean. exept this has for tires of the same brand and size, only the rear ones are abit worn.
i only drove a short trip and have put new gear oil in, this on a BRAND NEW Volvo Angle gear. so i dont think the angle gear is completley toast yet.

Im thinking it might be the viscous coupling thats doing this?

Im a Volvo mechanic, but these first gen AWD cars a far an few between in my country so not alot of people know about these