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Turbo Diesel Big End Seal Leak

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This is on an XUD7 Turbo Diesel, not the petrol XU9

I mention this because this topic has been raised and discussed previously



 I've read this link and anything else I can and still couldn't find any clear guidance/solutions


when bought, the engine had done 116000 miles

so before putting the engine into the car, (along with other things) I replaced the crankshaft big end seal, the input shaft seal, and resealed the sump

because the leak is along the join of the transmission to block

I thought all of these were possibles for the leak which is my current concern


after installing and running the engine, my first guess was this leak would be from the sump

and anyway, its easier to rule this out first

but the sump's been removed and resealed twice very carefully so its not that


then I bit the bullet and removed the transmission..

thought the other possible cause of the leak might have been the input shaft seal in the gearbox bellhousing

but it looks great, there's no leak there


so turning around and facing the other way, the leak appears to be coming from the cranskhaft seal

 this is already brand new, and the seal was installed very carefully to avoid all of this 

the inner lip is was not folded under or creased, the inner spring was still snug, and the cavity it went into did not have any sharp edges to score the outer rim


but I removed it and replaced it anyway to be sure

and first run all back together, the leak's still going !


the seal is ELRING 508.209, 90x110x7mm, its FPM not the PTFE type


all I can think of is that maybe I could take the transmission off again and seat the crankshaft seal a little deeper into its cavity


its a flimsy hope to do all that work just to tap a seal in a bit, then put it all back together and cross my fingers ?


in the earlier post above there was mention of cap side seals/hockey sticks


are they the joins in the block visible either side about half way up the seal ?


and could they be a possible cause of my leak and how do I fix them ?


the first pic is of the original seal before cleanup and removal

the second pic is after cleanup and the first replacement before running the engine

the third pic is the first replacement seal after running of the engine

the oil pooling in the last pic came out of the flywheel bolt holes when they were removed, so its still not obvious where the oil is leaking from or to


naturally, any suggestions greatly appreciated












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Check any breathers to see if the crankcase is being pressurised 

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thanks phil,

am I checking for a lot of pressure coming out the hoses ?

or none ?


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Had a similar leak problem on a 1.9  petrol injection, which I eventually sussed out to be crankcase pressurising due to blocked hole on inlet manifold which (via a small pipe to the oil filler neck) creates a vacuum on the crankcase taking fumes back through the engine. The pistons and crankshaft create a large amount of air movement in the crankcase which causes pressure (which you will feel on the hoses with the engine running) if not positively dealt with via the vacuum.


Not very familiar with the pipework arrangement on this diesel, but there should be similar arrangement.


Edit - (just remembered) sorted a TR7 some years ago that had enough crankcase pressure to blow oil up the dipstick hole. In that case that vacuum pipe fed into air filter box. The pipe was solid with gunge etc which prevented the vacuum.

Edited by PhilNW

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It wont be a blocked breather, it will be either  wear  on the oil seal land at the rear journal or the "hockey stick" seals have gone hard,which Is what my guess would be from t`other side of the planet. 


The breather pipe emerging from the block pointing forward just out of shot to the left goes hard and cracked where the metal stub and rubber pipe join, this is a common XUD leak and if it snaps completely it ruins the clutch friction material, they are available in cheap pattern parts from Autodoc, and are durable.


 The depth of the seal can be varied using an 8 or 10mm depth seal so you can get another "bite" at it if neccessary, its a common diameter.


Do the two "hockey stick" seals, fit them and leave them a day to assume their prefered "resting" length before cutting to size. I always do them, after a similar on off,on off,on off shenanigans 30ish yrs ago.


Today has fractionally more daylight than yesterday, roll on summer.



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2 hours ago, Ozymandis said:

The breather pipe emerging from the block pointing forward just out of shot to the left goes hard and cracked where the metal stub and rubber pipe join, this is a common XUD leak and if it snaps complet

They go hard and brittle then a crack opens just under the edge of the "one shot" hose clip, You cant see it and its appears to be the sump/rear seal/hockey sticks thats leaking.


You will ruin the hose removing it or its clip, if it turns out to be that ,make sure You have a new one to hand before You start, it will crack somewhere if You remove it.


The O ring sealing the oil filler/breather plastic moulding to the metal stub on the block occasionally goes hard and gives a similar deceptive leak.


FPM is correct.


XUD breathers are different from the petrol XU,  the diesels inherently lack manifold vacuum, hence the cam driven vacuum pumps. Theres a main breather pipe about 3/4"ish, that empties into the air filter and they are never blocked,although the filters are sometimes sopping with oil. The original filters were oiled foam not the paper type, the foam ones are better on diesels and last longer, the sopping paper doesn't pass much air. Theres a drain hole in the bottom of the plastic housing and there is always a nice stain of breather oil on the back of the radiator.

Edited by Ozymandis

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awesome, thanks chaps,

(we just had our longest day of the year and saturn and jupiter ligned up, apparently)


the blocked breather hoses was well worth thinking about, but I'd already cleaned that system out

and also, I think the crankshaft seal(s) was fine, even the original looked good and there was no evidence of obvious wearing in the seat


so the hockey stick seals are actually the breather hoses (hockey stick shaped) that plug onto the block ??

was confused about :

8 hours ago, Ozymandis said:

 The depth of the seal can be varied using an 8 or 10mm depth seal so you can get another "bite" at it if neccessary, its a common diameter.


dont understand seal depths and varied etc

aren't I just plugging a fresh hose onto a pipe and putting a hose clamp on ?

gunna have to hope I've not misunderstood, if Im goin the wrong direction give us a shout

the first pic shows the neglected old donk partly torn down before refurb



the two yellow masked off pipe stubs at front left are I think what you're referring to

the centre one for the oil filler pipe, and the left one next to the flywheel for the shorter of the hockey stick hoses


pic two shows the oil filler and hockey stick hoses gunked up



and then pic three is after clean out




PIC3, the filler pipe has 4 connections (and came without a dipstick in the lid)

from Bottom to Top

- filler pipe to central block pipe, o-ring seal with funny peugeot clamp

- short hockey stick hose to left side block pipe (this is the suggested leaker)

- longer hockey stick breather hose which goes up to cam cover, already renewed

- and lastly the top hose which comes over from the air intake


I'll order a new hose (or two) and may run with a leak til then

the hard old seals might bed in a bit with running - or get even worse - but not taking off the tranny again for now which is the important bit

see how it goes







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No the hockey stick seals are part of the rear main bearing cap assembly. You misunderstand several points.


part number 5 in this picture ,there are two ,one either side only ones shown here.




Heres some on the above fleabay link to look at.


They go hard then leak. The sump presses up against them and this is the leakage point most often.


If your hoses are off its easy to see if they are knackered, dont waste money if they are fine. They never block up but go brittle and crack, if they're flexible then you should be fine. The lowest hose by the starter cracks under the hose clip where it joins the metal stub, thats the one that gives an apparent sump leak.



As to varying depth, what that means is regarding the rear crank seal the circular lip seal. Where the lip runs on the rubbing surface, the land, it wears a groove, if you install a new seal with the lip in the old groove then it would leak. But if You move the lip in or out to run on a fresh unworn part of the land then it wont leak, different types and variations in depth of installation can be used to put the lip on a good bit.


Its dark by 1/2 past 4 here, winter ,cold, wet, and frosty tonight. Bleak midwinter style of thing. My turtles been asleep under the side board on an electric blanket for days, she hates this time of Year, as do i.




Edited by Ozymandis

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bloody hell

leaking crankshaft bearing seals ! sounds like a wind up

bit shocked


right, so I was off on the wrong track

well, sorted the front hoses anyway, need to order a newby short one

will order a set of those hockey stick seals pronto too for the major leak

hoping the procedure is not too involved as I've never taken a crank out and didn't want to right now

rather remove the sump, unscrew a bolt or two and insert seal


also, when the crank seals leak, they're still in the sump so why doesn't it leak into the sump instead of onto the floor ?



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2 hours ago, Gohn said:




You wouldn't say that if You were sat in my shed typing this with fingerless mittens 2 pairs of military socks and a hat on. Its a bright late afternoon  suns just about to go down at 3:30 ish and the air temp in the sunlight's a whopping 2 degrees above freezing. My ears are cold.


When the hockey sticks leak, Oil gets in the vertical seam/part line of the main bearing cap and runs out at the bottom of that appearing to be either the sump seal or crankshaft lip seal. You can clearly see the line I mean in Your pictures the vertical split line.


I presume You`ve got the idea with the hockey stick bollocks now, look up the fitting procedure they are a fiddle to do and easy to get wrong or damage, i use two sheets of hard clear plastic cut from rigid vacuum moulded packets as seal protection against knicks and tears I also coat the lot with Wellseal beforehand. When they are in, your supposed to cut them to length, leave them a day before doing so as they contract a bit so would leak if You did them straight away.


You only need to remove the rear main bearing cap its simple enough but a big pain in the backside. It can be hard to pull it out Cant say I ever did one with the box in, its always been out anyway when I have done them.  Im looking at one right now and the pictures in the manual, looks possible to do with the box in and flywheel on, but dont quote me on that if it isnt. You may have to screw something into the 2 sump bolt holes and slide hammer/ puller it out exactly vertical, who knows give it a go as your only removing s*it You would have to remove if You do end up dropping the box. The haynes XUD manual covers it very well, lots of photos and advice

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thanks jay,

true, frozen fingers fixing cold metal parts is no fun

and military socks are scratchy, sweaty, awful

git some bamboo ones, you'll neva go back


hockey stick seals ordered

can't wait to see what installation's like

done the groundwork for another tranny off jobberty, but wont be exposing the crank to the air until the last minute when the seals arrive

was initially a bit concerned about taking the tranny off, but its actually pretty good, as per

the "Gearbox Swapping Guide"


only realised this was in there after already taking mine out ,and in..




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14 hours ago, Gohn said:

git some bamboo ones, you'll neva go back

Dont You get splinters in Your toes?



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hermm last update was late Dec 2020

ran engine again this afternoon, still leaking . yay

pic one is the drip oil puddle after 15mins running


if anything it looks like a "neater" leak, just one drip point off the bottom corner of the sump, everything else bone dry


regarding the hockey stick seals:

I did not use shims to install seals , had 0.20 plastic sheets but even they would not allow the crank bearing cap to slide back up/in

so just oiled outside of seals and slowly slid up vertically into place

put small amount of silicone sealant into top mating surface of bearing cap cavity

used permatex liquid gasket stuff onto hockey stick seals, then put them on crank bearing cap

was worried may have cut/knicked seals so removed the bearing cap after first time but the seals were good

the seals get stretched by installing them in their narrow channels

waited a day to trim to +1mm from the sump mating surface as per book


old seals on left that take on the angled shape of the channels, new round ones on right

pic 6 shows the new seals installed prior to trimming off


back n try again spose













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I've struggled a lot with these myself too, but at least I got two of my 3 engines confirmed sealed now.


I have just applied a slight amount of gasketsealant on the top where the hockey seal sits over the pin in the bearing cap (in addition to the small part of the corner of the bearingcap that needs sealant), but nothing down the side-channel of the cap, as I found the seals seemed to stretch more if I used sealant. Instead I lubed the side of the block with engine oil, and also the hockey stick seals outside, no lubing in the channel of the bearing cap or inside of the seals contacting this channel, so that friction is bigger there than where the hockey seal slides up in the block. This way the seal is more likely to stick to the cap when pushed into place, and just slide along the block. I also let mine sit overnight, but I could not measure any difference in protrusion even after 48 hours, so that didn't seem like a must really.


Then I cut them protruding about 0.8-1mm. Sprayed properly with brake-cleaner between the bearingcap and block mating to wash oil away from the seal several times just to make sure the sump sealant would stick properly to it when sump was installed afterwards.


Ideally after installation you should see that both the seals protrude approximately the same from the block too, if not one might be stretched too much.


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excellent detail kristian, that's very helpful

its kind of confirmed my suspicions

one of my hockey stick seals was longer than the other after installation just as you said so that's what I was gunna go back in and focus on

I did use that permatex stuff in the bearing cap channel so maybe your friction theory is also spot on

either way, this time I'll do as suggested and lube the outside of the seals and the block wall, leaving the channel clean to hold the seal firm


its a bit weird to have two super sensitive seals located in such a difficult location

with a peugeot tool that I've never seen to install them

difficult to diagnose, take apart, install, rebuild and test

and if the removal/install/rebuild and test fails its days of work to do over

at least the hockey stick seals are cheap


thanks again



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1 hour ago, Gohn said:

its a bit weird to have two super sensitive seals located in such a difficult location 


It's crap by design !! ..


Me too , what ever i tried had seldom success sealing XU end caps .. and all the XU's i've seen through the years did the "pissing act" from that sump-flywheel corner area , can count on one hand just a few of them which where dry . Those where still factory made engines never taken apart and probably well looked after with regular oil changes so that the seals retained flexibility .


Here's pic of the OE tool for installing them :







Personally , i use an tin can of juice beer or similar ... cut into two pieces to guide/slide the cap with the seals in the block (with some liquid sealant as an additional sealing aid + lubricant for ease of installation) :





Also , in the OE Peugeot manual they say liquid sealant had to be applied on the bearing corners and ends :





Wish you best luck with this job !



Edited by DamirGTI

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thanks very much D,

17 hours ago, DamirGTI said:

It's crap by design !! ..

I was trying not to offend other 205 owners on the forum, huh,  but now that you mention it, that's how I'd describe it privately


its pretty appalling that peugeot designed a crank bearing cap into the block wall.

the design is relying on the most sensitive seals I've ever seen to form the barrier to the exterior of the engine

it would have been far easier for the engineers to install the end cap INSIDE the block wall and covered by the sump, removing the need for stupid seals or leaks that are diabolical for owners to fix

thought it was me, only to discover every XU and XUD has the same problem, INBUILT, ON PURPOSE, BY PEUGEOT


anyway, I've begun the whole removal/fix/reinstall/test process again (lost count how many times it is)

its very encouraging to hear of others experiences with the same problem and read thru the information you've posted


was especially interested in your workshop manual pics, where it suggests putting a little more sealant on the top mating surface at (a)

was still a little unsure of that, so I'll do it this time

I've also decided that I wont rebuild anything unless I like the look of the newly installed seals, if they look like they've stretched too much or one's longer etc I'll just redo until happy and only then put it all back together for the run/test


very impressed with your ally can seal protectors !

nice work, that's clever, why didn't I think of that

here goes again


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Tom Fenton

Pretty appauling is a bit strong. Assemble it correctly and it won't leak, I've done lots of them.

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oops, apologies as per previous


if you're able to excuse my carry on it'd be great to hear your procedure

its pretty clear I was fumbling in the dark a month ago

and if you've done lots of successful seal changes then that'd be 'lots' more than me

I've gotten a little better but still yet to do even one successfully

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ery interesting to read about this. I'm about to get one of my cars in traffic next summer and one of my issues is oil leak on that area..


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all back together again, and sealed

not even excited anymore

so I check again, and again, run again, check again

no leak, not one drop

first proper drive will be to get rego so not positive yet

I could wait and update after several solid highway runs, but where's the fun in that


obviously not any expert, others have more experience than me with this issue

but in lieu of information from those that are, hopefully a recap of what I have found will help others

because I could easily see this issue ending a restoration or benching a car for good


crank bearing cap (hockey stick) seal #012740 same for XU petrol (70mm long when new)

XUD big end seal #011906 (90 x 110 x 10mm)

XU9 and XU5 big end seal #012728 (90 x 110 x 7mm)

sump gasket XUD and XU9 and XU5 #030434

silicone sealant: Three Bond - Grey

Liquid sealant : Permatex Aviation Form-a-Gasket


as mentioned at start, mine is a Turbo Diesel, XUD7

there may be some minor mm variations between petrol and diesel

but I believe its the same process to seal up the leak


also, mine was an ENGINE IN fix

if you already had your engine out for a rebuild etc its much easier to work on it upended on the bench

I was under the car, in between hoist legs etc so its difficult, awkward and cramped but better than a full engine out job

the basic process is :

remove gearbox, clutch, flywheel, sump, and crank bearing cap on the flywheel end

replace hockey stick seals and big end seal, seal up with silicone seal, put all back together


check the Gearbox Swapping Guide for more fulsome explanation, but its

jack car (6 notches up on stands) - not too high, not too low -

wheels off

drain gearbox, drain engine

cover your rear radiator face with cardboard or foam sheet to protect it, only takes a second and they are easy to damage

disconnect everything from your gearbox, clutch cable, speedo cable, electrics, starter, tacho sensor, driveshafts, power steering pump

attach hoist to engine and take weight of it

remove bottom/rear engine mount bolt to subframe only (leave yolk in place)

unbolt LF engine mount centre nut, remove rubber mount from batt tray but leave tray in place

now all you're engine/gbox weight is on the RF engine mount and the hoist

lower the engine/gbox down carefully, about 3 inches or so

position a floor jack under the tranny to take weight as it cames away from engine

remove in order the 1 bottom/rear and then 3 top/front engine/gbox fixing bolts

carefully move the jack out and down with the gbox on it thru LF wheel arch, its a tight fit


put a reference spot on your clutch, flywheel and block to realign when putting back together

I lock up the engine with bolts thru cam/pump pulleys, and flywheel hole but up to you

inspect as you go...

remove clutch (careful with these bolts, the book recommends 50Nm torque when installing on these but that felt crazy to me and sure enough one of mine sheared off at about 20)

remove flywheel, clean bolt threads and I reuse these with threadlock (ideally new ones are best but I would have gone thru 4 sets already doing this..)

do a rough eyeball check of the depth of the big end seal, usually about flush but can be recessed into cavity about 10mm if needed

remove sump, marking bolt locations (all mine are the same length but are supposed to differ ??)

clean sump mating surfaces upper and lower nice and clean

remove the two number 1 crank bearing cap bolts (flywheel end) and pull the bearing cap piece out ,may be a bit sticky but break it sideways a bit and slide

remove old hockey still seals and the big end seal and clean the crank bearing cap


I used the Three Bond silicone sealant on both the top mating surface of the bearing cap AND the chamfered shoulder

I previously tried the Permatex liquid sealant on the top of the hockey sticks and down the channels but did not for the last time

but there's no harm in using it if you want, it did not make it harder to install the bearing cap/seals

I was a bit concerned with silicone sealant squeezing from the top mating surface onto the crank bearing

but the Peugeot workshop book that Damir showed was important

the haynes book mentions sealing the chamfered shoulder but not the main mating face, so I followed that and it leaked BAD

once I followed Damir's suggestion and sealed both the shoulder and main mating surface it was good

the pic shows that I used enough sealant but not tons


on with the new hockey sticks

put your new seals on the bearing cap, put your silicone sealant on the upper mating surfaces as shown

then oil the outside of your seals and dont forget to oil the crank cap bearing surface

and slide it straight up slowly and carefully bit at a time

I wanted to try going in sideways so the seals dont stretch as much but it just did not work for me


also, the pics show the difference between a new seal and a set of trimmed ones that are uneven

the very top of the bearing cap is widest (see crankleak5) and squeezes the seals against the wall as you insert the cap

each time I inserted the bearing cap, the forward seal would stretch much more than the rear one no matter what I did

at the end the forward seal was about 13mm proud of the mating face, the rear seal 9mm

I thought this would have been too much stretch to achieve a seal, which is why I removed them twice each time and reinserted them

but its not leaking now so it seems that this amount of stretch is ok


upside down its not possible to cover the block sides with aluminum can like Damir but if I was on a bench I would as the can is perfect (0.15mm thick)

I put four sets of seals in without using any guides/shims like the can

and the three I checked afterwards (plus the set still in there) have no knicks or cuts in them


once its almost all the way in, insert the bearing cap bolts and gradually tighten up

(the book recommends 40Nm, then release, then 20Nm, then 70 degrees rotation)

this looks stupid and I really dont trust the recommended torque settings anymore but use them without any other better information and did here

trim the seal ends that stick out from the sump mating surface with about a 1mm excess using shims and a razor

I didn't experience any shrinking or settling so you can trim them immediately

clean the sump mating surface really well and put some silicone sealant on where the bearing cap joins are

line up sump gasket with sump and put up and bolt on. the gasket will push the sealant into the bearing cap joins too

also, I only realised late that I needed a sump gasket. I've removed two diesel sumps and neither had a gasket at all so I assumed that was what to do

the XU9 has a sump spacer too, but anyway dont be bodgy, get a sump gasket !


with the bearing cap seals and sump done install a new big end seal if at all doubtful

its almost impossible to be sure if a leak is coming from the hockey sticks or big end so I'd recommend a new one to be sure

remove any excess silicone from the big end seal cavity

inspect the big end seal seat for wear and oil the outer and inner rings of the seal

if there's a worn ring line on the crank where the inner lip of the old seal sat, you could insert the big end seal at a different depth giving a much better seal

but if it all good just insert to about where the other one was

also I found that the inner lip never folded over as the book warns. I always tap it in with a soft bit of timber working around the outer rim

if I needed to push it in a few mm deeper than flush I used the old seal tapping around the outer rim

do check the inner lip though to make sure it points outward, never seen a folded over lip but I figure it'd be fairly obvious

then, put all back together again

manouvering the gbox back into position is difficult

first time I got lucky and it took me about half an hour

then the next 4 or 5 it took hours each time, hours

when thats done run engine stationery to operating temp, check for drips

go driving, check for drips again


I'll need to wait until its done a few hundred clicks, and then guess what

onto my other one ..

And Im very grateful for your own experiences, suggestions and info


















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Nice that it got sealed at last..


I have just confimed all my 3 cars also is sealed now, good feeling :)

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Hello:. Has anyone ever considered of fitting 2 viton rear crankshaft seals (One on top of the other). They are 8mm height and i believe there is enough space for them. It seems like a great idea at first but has anybody tried it?

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Fit bigger/deeper seal rather than two ... i've done that on a few occasions .


OE crank seal dimension is : 90x110x7


Deeper version : 90x110x10



Edited by DamirGTI

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