There has been a slight oil weep from the transfer box since the day I had the Defender. It looked to be coming from the intermediate shaft/case as is common so I wasn't overly rushed to look at it.

More recently the rear output seal had started leaking so I took it as the nudge I needed to get the transfer box off for a rebuild.

Removing is a bit of a faff with a couple of fiddly connectors and linkages to disconnect. The floor panel beneath the cubby box provides good access. Propshafts disconnected and exhaust split after the catalytic converter. Handbrake drum removed and finally unbolt it. My Dad was helping so we slung the box with rope and as I unbolted/slid it off the gearbox output shaft he lowered it to ground from above. Seemed to work ok but I think we will need more help to get it back in!

We re-cased the transfer box into an Ashcroft sleeved case with an Ashcroft master rebuild kit. Took the opportunity to upgrade the diff with an Ashcroft HD cross pin. I found some copper shards in the old box and it turned out that the diff planet gear thrust washers had disintegrated to nothing. This was causing the planet gears to run at the outermost edge of the shaft resulting in slop in the gear mesh. New ones fitted and all good - hoping this tightens a little driveline backlash too!

Overall not too bad a job, just following the rebuild manual which is very detailed. Time consuming though and mostly cleaning

Was pleased to see the Ashcroft gearbox output shaft was still looking spot on after being fitted for three years!

HD cross pin

Click image to enlarge

Sleeved casing

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Rebuilt rear

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Rebuilt front

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Transfer box is back in the Defender. Serious improvement in terms of backlash and leak free!

Refitting was relatively straightforward... We tied rope around the box and lifted through the floor panel while I aligned it onto the gearbox shaft from underneath and put a bolt in.

Trickiest parts of the whole job I found were refitting the diff lock selector arm and tightening the prop shaft nuts - so fiddly!

One more pic of the ashcroft output shaft to close that chapter


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Hank, do you think it was the Ashcroft rebuild kit, output shaft or both, that really reduced the backlash? The rebuild kit is quite a job, whereas the output shaft is a common upgrade I’m thinking of DIYing.  Monsieur Le Grenadier

I've not been everywhere, but it's on my list.....

2011 Puma 110DC - Corris Grey

The breakdown of the centre diff thrust washers will have resulted in a lot of backlash in this box.

 Monsieur Le Grenadier

I've not been everywhere, but it's on my list.....

2011 Puma 110DC - Corris Grey

As black wolf says the backlash was, without a doubt, coming from the lack of washers in the diff planetary gears which would have allowed the planetary gears to run further "out" (for want of a better term) where they wouldn't mesh properly due to being bevel gears.

The output shaft is only really an issue if you have a leak > 110 XS Double Cab
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hank wrote:

...The output shaft is only really an issue if you have a leak

Hahaha true dat > 110 XS Double Cab
> Instagram @simonlanemind

Recently I've been experiencing the occasional "P0234-00 (28 ) turbo overboost condition" error which puts the vehicle into what feels like normally aspirated / limp mode until the fault is cleared.

Research suggested this could be a sign that the variable geometry turbo vanes were gunked up and sticky and I figured this was likely due to manky crankcase fumes being recirculated into the turbo inlet.

As a test I disconnected the crankcase pressure recirculation hose from the turbo inlet, venting it to atmosphere. I also sprayed a can of wynns turbo cleaner through the turbo for good measure.

Sure enough 2000 miles later no further overboost errors. However, the crankcase fumes were pretty bad so I needed a permanent solution. (It would also be an MOT fail)

On investigation, the rocker cover pressure relief valve diaphragm had gone hard and crusty so I replaced that with a nice new flexible one

While I was there I also fitted a Provent 100 - I went for the 100 because it's compact which is advantageous given the limited space in the engine bay but also because the inlet and outlet are 19mm which is useful as they match the existing Defender breather fittings so no adapter fittings required.

Today I fabricated a bracket to mount the Provent which picks up on the clutch pedal box cover screws and plumbed it courtesy of a Corsa 1.3 CDTI breather hose from rocker cover outlet to Provent and the original, trimmed, Defender hose from Provent back to turbo inlet.

Pleased with how it turned out, looks kind of OEM and the fumes exhausted from the Provent are spotless whereas previously they were grey smokey/oily and rank.

Anyway, a few photos...

Cardboard template for the Provent bracket. Unfortunately I forgot to take a photo of the steel bracket which has welded nuts for mounting the Provent

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Provent fitted and plumbed.

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> Instagram @simonlanemind

Last edited by hank on 25th Aug 2020 7:38pm. Edited 2 times in total

Nicely done. You'll be surprised how much oil it catches. WARNING.
This post may contain sarcasm.

Yeah? I've put a length of opaque pipe on the waste as a temporary measure but will fit a transparent hose and tap arrangement when I get one so I can monitor the waste oil level > 110 XS Double Cab
> Instagram @simonlanemind

Rocker cover subcover fitted
Why does this part have sealing o-ring but holes open to atmosphere below


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> Instagram @simonlanemind

2 questions.

What is that for?

and

Where do you put your beer/tea/fixings? WARNING.
This post may contain sarcasm.

And the final piece of the provent puzzle... Waste drain and tap plumbed to behind the front offside radius arm mounting, retained by a hose clip in an existing hole


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> Instagram @simonlanemind

Zed wrote:

2 questions.

What is that for?

and

Where do you put your beer/tea/fixings?

Its primary purposes it to avoid comments like those below Beer goes in my mouth and fixings typically into the drain

Mo Murphy wrote:

You have a cup holder in your engine bay, that's useful !