Why am I losing oil from my transfer box breather?

[fv1609]

On the pig, the gear box is connected via a prop shaft to transfer box at the rear which is mounted in front of the rear diff. It permanently feeds another prop shaft to the front where FWD can be selected.

 

I am losing oil from the transfer box breather & after a run of more than 5 miles the transfer box feels a lot hotter than the diff, but I don't know if that is normal.

 

The trouble started last year. The TF/box oil level was going down & was ending up in the diff. No external leakage at all. The TF/box breather was not blocked or damaged it seemed.

 

During the winter, I removed the TF/box. Although the main seal from the TF/box shaft to the diff looked good, I replaced it.

 

This year after it had a good run of 35 miles found I was losing oil through TF/box breather. I replaced the breather & in case the diff was pressurising removed the diff breather.

 

Still got oil leakage. So to get me to Kemble (65 miles) I put a breather pipe 18" long up from the breather hole. No external leakage but oil still getting blown out of the tube.

 

I drained the TF/box & found pieces of metal. Dismantled the box & found a mangled spacer washer (3.5in od, 3" id). I think I messed up as it was tight on reassembling the shaft.

 

I had what I believed to be an OK TF/box on another chassis & fitted that. After 5 miles no leaks but after 12 miles, leakage through the breather & diff feeling much hotter than the diff, just as before.

 

It is not stuck in 4WD. The oil is OEP220 as indicated in Servicing Schedule & stencilled on the side of it. It came from a sealed military drum of recent manufacture.

 

I was at show recently & saw a Humber GS. I asked if he had leakage problems, apparently not. But I could see the TF/box smothered in old oil & on checking the level found his TF/box was empty.

 

So any ideas please?

 

& why do these things have to happen mid-season

[paul connor]

I know mine leaks all the time, I have tried some "sealent" stuff you add as it assumed its the gasket...mine may be the same issue? we shall check at War and Peace...

 

I always top up before moving the ol girl

[fv1609]

I know mine leaks all the time, I have tried some "sealent" stuff you add as it assumed its the gasket...mine may be the same issue? we shall check at War and Peace...

 

I always top up before moving the ol girl

 

 

Would be worth cleaning it off & seeing if it does in fact dribble from your breather. I don't get this problem from the other pig & hornet. But I have not before been concerned about TF/box temp (but can't run other pig as engine now kaput & from hornet can't run that till steering sorted)

[paul connor]

its another job at WP show for me! 10 days under a Pig, i'm actually looking forwardto that

[ian2b]

its another job at WP show for me! 10 days under a Pig, i'm actually looking forwardto that

 

 

Now thats not a nice way to talk about the women of Brighton and I bet its not the first time you have spent time under a pig - have heard your not to fussy :whistle:

[paul connor]

haha you wait till WP show :evil:

[ian2b]

haha you wait till WP show :evil:

 

 

See you there :beer: :beer: :beer: :beer: :beer:

[hardyferret]

Come on all the ex-REME..

 

Clive and I have sratched our heads any thoughts :?

 

HF :dunno:

[Richard Farrant]

Come on all the ex-REME..

 

Clive and I have sratched our heads any thoughts :?

 

HF :dunno:

 

 

Well, I would say that the oil is heating up for some reason, due to friction. I have seen this on Ferret bevel boxes, when the inner tracta has started to "weld" together, it used to blow oil out of the breather. Trouble is, without stripping, it is hard to guess.

[hardyferret]

Transfer box has been changed

 

Old unit us, v hot spacer found in bits in it, new box fitted Clive reports that this seems hot as well??? :?

 

HF

[Richard Farrant]

Transfer box has been changed

 

Old unit us, v hot spacer found in bits in it, new box fitted Clive reports that this seems hot as well??? :?

 

HF

 

 

Right oh, just looking at the parts book and can only think now that it is a problem with the axle. The axle pinion loading the splined shaft in the t/box. Not sure of the set up, but maybe there has to be a precise thickness of gasket between the t/box and axle. If too thin, it loads the transfer box. This possibility is the only thing that would influence both transfer boxes.

 

[hardyferret]

Richard this could make sense as Clive initially had the axle go this was changed and from then one this saga commenced....

 

Would make sense, with the heat being built up in the transfer.

 

I will have another look at the exploded drawing and See what info Clive has on the build of these assemblies.

 

Many thanks HF :bow: :bow:

[fv1609]

So last summer was the problem oil from TF/box to diff.

 

Winter removed the TF/box & replaced the main seal between TF/box & diff. The TF/box was very difficult to dismantle.

 

http://img.photobucket.com/albums/v684/fv1620/DSCF2822.jpg[/img]

 

The spacer can be seen on the diff & a 2 shims.

 

http://img.photobucket.com/albums/v684/fv1620/DSCF2820.jpg[/img]

 

As it was such a barman to remove it was no surprise that re-assembly would be equally difficult. In retrospect I assume I had caught a washer which got mangled & I found this on dismantling after Kemble.

 

http://img.photobucket.com/albums/v684/fv1620/Dscf3806.jpg[/img]

 

I took another TF/box & fitted it with its spacer & several shims which were associated with it.

 

http://img.photobucket.com/albums/v684/fv1620/DSCF3828.jpg[/img]

 

Yes Richard can only explain it by getting too hot & bubbling out the breather. I cannot find out from Humber owners if they find the TF/box gets significantly hotter than the diff.

 

Checking a FV1601 at Ardingly, we found all his TF/box oil had been lost through the breather. I have checked the level in the Hornet & that is significantly down. So it seems to be a common problem. But my dead pig which drove 130 miles engine failure was serviced before the disaster. There is no sign of TF/box leakage & level is correct.

 

The EMERs only cover Field & Unit repairs & are no help. So is the choice of spacer shims critical & how does one set it up correctly?

[YK55]

So is the choice of spacer shims critical ?

 

 

Absolutely! Just look at the stack of them you have there, they are obviously important. If you don't have the correct clearance then you will be pre-loading some component causing friction and subsequent overheating which will pressurize the transfer box and cause the leak. Can you work out whether more or less shims will give you a clearance? Better to have excess clearance than none at all.

[fv1609]

Yes, well when I had 2 shims, I got overheating. Both TF/box & diff have tags indicating they had Base Wkshp overhauls at the same time.

 

On second transfer box I used the 4 shims that were there but, I don't know maybe I should have tried 2? Although I would have thought more shims meant less risk of over engagement & heat?

[YK55]

I'm guessing that the amount of shims affects the pre-load on the end of this shaft?

[MiketheBike]

I tried to get my head around this with the Ferret bevel boxes, and came to the (incorrect?) conclusion that:

 

the tech notes say there should be a preload of 0.000 to 0.002 inch.

So rather than bolting the plate down to preload the bearing, hold it hard against the housing and there should be between 0.000 and 0.002 inch with the correct spacers...if that is correct, bolt it down and it gives the correct preload.

I would guess if there are too many spacers it could equally heat up as the bearing would not be seated correctly and you would get hot spots on teh bearing?

 

http://www.tpub.com/content/construction/14273/css/14273_197.htm

[fv1609]

Andy & Mick, thank you for your input on this puzzler. I get a bit befuddled as the splines engage linking the diff to the TFbox & they do this with about an inch of engagement. Looking at the shaft from the dissected TF/box & playing with it in the spare diff, it seems to have plenty of room for engagement of appx one inch. I find it hard to grasp that if is a few shims either way it would make the slightest difference.

 

But as you have pointed out it must be important as shims are provided. Given such depth of engagement I can't visualise in practical terms. How I can determine at what degree of shimming I use given that the two units mate quite successfully with no need force them together.

 

The Inspection Standards for the TF/box only give a figure for the tolerance of backlash between the gears, so not much help there.

 

I think I might take the dissected TF/box to W&P. So if anyone can give me description with the item at hand I would be most grateful. I shall be in Wolf + Cipher trailer in Living History with Ex Mil Land Rover Assn on the main road just over the bridge from the showers. Thanks.

[YK55]

Looking at the shaft from the dissected TF/box & playing with it in the spare diff, it seems to have plenty of room for engagement of appx one inch. I find it hard to grasp that if is a few shims either way it would make the slightest difference.

 

 

Looking at it again I think you're right. The shims are in a strange place if they were to adjust the fit between transfer box and diff. Why would they not just put them between the flange and the diff? So, the amount of shims at '1' affects how far the flange slides into the transfer box, the distance '2' is not critical. So what is on the other end of the flanged piece, down inside the transfer box?

[Richard Farrant]

The shims are in a strange place if they were to adjust the fit between transfer box and diff. Why would they not just put them between the flange and the diff? So, the amount of shims at '1' affects how far the flange slides into the transfer box, the distance '2' is not critical. So what is on the other end of the flanged piece, down inside the transfer box?

 

 

The shims at "1" are critical and should not be altered. They adjust the depth of mesh of the pinion to the crown wheel.

[fv1609]

The shims at "1" are critical and should not be altered. They adjust the depth of mesh of the pinion to the crown wheel.

 

 

Looking in the IPC I see shims were available in 2, 3, 4 & 25 thou. Obviously extremely critical. But:

 

a) I have difficulty grasping why it is critical to that extent.

 

b) I have difficulty grasping how this can generate more heat in the TF box, if the spacing influences the pinion to crown wheel in the diff.

 

c) Have no idea how the correct shim combination is achieved.

 

d) If the shims directly influence the pinion-crown wheel relationship are they in effect a diff issue? In the sense that whatever TF/box I fit I should always use the shims & spacer plate that were associated with the diff that they came from?

[R Cubed]

Not rearly sure how this bevel box works but I reacon looking at how thin some of those shimms are they are to set the correct pre load on the bevel box bearings and has nothing to do with the spline engagement of the shaft, I will also be up at Beltring so could put in my two pennith if you like.

[fv1609]

I have been playing with the shims & pinion on the defunct donor axle. I now fully appreciate that the shims have a very crucial role to the preloading of pinion- crown. Sorry to have been thick to those who are trying to help me.

 

Having played around I realise I would not in fact have changed the shims. I realise now I had only thought about it. The defunct diff have shims are covered with red sealant that matched up with the deposits on the diff. So sorry for misleading info.

 

The shims on the diff are the original set as provided at REME rebuild. Comparing earlier photos all I had done was to clean up the shims & to do this they got separated.

 

So the problem is to ascertain if the shims are correct. But surely any excess heat here would have generated extra heat in the diff not in the TF/box?

 

As both the TF/box & diff had REME rebuilds at the same time. I would tend to feel that it would have been set up correctly. So that then comes round to the problem of why extra heat is being generated in the TF/box, sufficient to cause expulsion of the oil from the breather?

 

 

[R Cubed]

Do you think the oil is getting that hot that it is boiling and so getting out through the breather ?

 

What does the transfer box do in your vehicle, ie what does it link to what ?

 

Are you sure you have the correct oil in it ?

[fv1609]

Do you think the oil is getting that hot that it is boiling and so getting out through the breather ?

 

What does the transfer box do in your vehicle, ie what does it link to what ?

 

Are you sure you have the correct oil in it ?

 

As TF/box gets hotter than the diff I imagined oil was being heated up & expelled through breather. But I don't know if TF/box is more likely to get hot normally.

 

TF/box is at rear, prop shaft from front drives TF/box to rear diff. TF/box also drives prop shaft to front where power can be engaged to drive front wheels for FWD. I have checked it is not stuck in FWD.

 

Oil is OEP 220 as painted on TF/box & stated in Servicing Schedule. It was from a sealed drum of genuine military stuff & has been used to fill up the diff & tracta joints.

[R Cubed]

Oh so normaly on the road it only drives the rear wheels ( 2WD ) so you should not be suffering heat build up due to wind up in the t/fer box.

Is the problem heat or just the oil being expelled through the breather, is there a baffel missing below the breather ? like you get on some rocker covers on cars !!!!!

Is this a widespread problem, do others suffer from it, are you over filling it ?