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Oil leak from bolts on aluminium sump


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Hi Panch

if the sump were porous then surely it would be wet with oil on it’s bottom face?

if it isnt then i’d investigate the gasket first as this is cheap and easy

my 10p is still on gasket :-)

steve

Edited by Steves_TR6
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Hi Panch,

please let us know how you find the seal. It is "broken in pieces" or  deformed between the bolts?

This can happen at the steel oil sump when the bolts are locked too tight.

This punches the steel flank and the seal suffers from that on every bolt.

Until now I expect this can not happen on an aluminum sump - but who knows?

See this post from 2013, german, but the photos tell you

Ciao, Marco

Edited by Z320
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Hi Marco, will do... 

So I had the car. up on my ramp last night to have a good look at the sump.. there is definitely a fine film of oil all over the sump, but it's hard to tell if this is seepage through the sump itself, or whether it is as a result of the oil spray from the leaks around the bolts... if I had to make an intelligent guess, I'd say it was coming from the sump itself as it seems to be everywhere rather than just in patches around the bolt areas. I'm going to degrease the outside of the sump this weekend I think and then try not to do drive the car for a few days and see if the oil comes back on the surface.. Will keep you posted..! 

Panch 

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Hi Panch,

If you're replacing the sump gasket, Jigsaw Triumph have an extra thick version that's well worth considering. It's made from a traditional thick, impregnated cardboard material. I've used one recently and was impressed.

Jigsaw's website seems to be in redevelopment, so best to call Mark Field on +44 (0) 1536 400 300.

Nigel

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Sounds like the usual porous casting to me in that case. Go back to the steel one if you still have it..

Stuart.

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The other thing to consider is whether your block is true.

Many have warped to a minor degree over the years of heat/cool cycles.  This is no big deal for a steel sump which flexes and takes up some of this gap.

The alloy sumps are more rigid and if the are true and the block isn't the gasket won't compress evenly and thus leak.

 

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I was lucky to buy a seal from a garage clearing not made of card board but of cork via eBay.....for my TR4A.

Never have found another one before and after.

 

Edited by Z320
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Hi Panch,

if you have the sump off, after cleaning both faces, install it without a gasket first, just on 4 bolts, hand-tight. You can then check if the sump and block mating faces are parallel.

If you doubt the casting (porousity), try a thorough clean and water glass first before final fitting with a new gasket.

Waldi

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.

To be frank I'm rather amazed at the harking-on about a porous aluminium sump, which seem to ignore (..in this instant) the oil would have to defy gravity to get up to the rim, to then run down onto the bolt heads. !   I’m fully aware that turbulent air flow can contribute to this phenomenon but unless the bottom of each of the sump fins have been wiped clean but the bolts have not - then the photo suggest this not to be the case.  

Naturally a soft-compound gasket is used to accommodate any surface imperfection of those mating faces. The higher the manufacturing tolerance and the more stable the mated materials : the less gasket thickness / compliance is required.  For example, a gasket is generally very thin or not required at all during assembly of an oil pump, whereas for unstable and different materials such as a pressed-steel sump and a machined cast-iron crankcase - the gasket will be thick and very compliant.

A gasket's purpose is to prevent fluids moving laterally across a mating face.  And almost always, the hole in the gasket is bigger than the stud or bolt, and therefore there is always a gap sufficient for hot oil under both gravity and crankcase pressure to seep through.  If the hole were not bigger then you'd have to tap the screw thread in through the gasket every time you fitted a stud or bolt. In many instances this 'self-tapping' may occur on one side of the gasket's hole but rarely is it all around that hole ..because manufacturing tolerances of the crankcase’s bolt pattern and the holes through an after-market gasket would not be accurate enough for an interference-fit. 

Similarly, the holes through the sump’s flange must be loose enough to account for any variation in the crankcase’s stud pattern  ..as well as to get the studs / bolts through the sump even when crawling around under a car.   

Furthermore, because aluminium has a different rate of expansion to the cast iron crankcase, design allowance need be made for fitting these at different temperatures.  Of course aluminium sumps and rocker covers fitted to iron engines will always be prone to leak unless there is sufficient allowance for thermal-expansion (..more prevalent on large hollow-shell casting than on smaller components).  In the old days this was usually accommodated by using a thick cork gasket and very low fastening torque. Nowadays card gaskets are made and used ..but only because they are cheap to stamp out and then easy to handle for volume production,  but they are not nearly as stretchy, so as the different-metal parts thermally expand and contract / move relative to one another ..their seal breaks. 

A couple of months ago,  I bought (cheaply available off a well know auction / buy-it-now site) a one-square-metre x 1.5mm thick sheet of cork to make gaskets for a vintage motorcycle, specifically its aluminium sump.  In this case I've used 'Heldite' to bond one side of the cork to the sump. In doing so, I fitted the sump ..evenly but only very loosely (so the jointing compound didn't all squeeze out) to allow the compound to set.  Now fitted and in use ; the other side of the gasket is still without sealant of any kind, and I'm using just 6-ft-lb torque on its fastening nuts. They did need re-tightening after a number of thermal cycles, but they remain oil tight.  

An advantage of thick cork gaskets, over paper and other composite types, is that they are stretchy to pull over sump studs. This means that their hole size can be tight on the stud and yet dimensional tolerances in stud pattern are easily accommodated. They're not nearly so easy to fit when using bolts (rather than studs) but usually it is possible. The additional and great advantage is that cork bulges sideways very much more as it is compressed, so a hole through a thick cork gasket will pinch even tighter onto a fastening stud or screw thread.  

Fastenings. I see in the photo that your sump is fastened with bolts. But I wonder if they have plain shoulders ?  Otherwise you are trying to seal something with a serrated edge. And unless those are thoroughly clean ..and sealant is wiped into those threads before fitting (I'm talking about the bit which is through the sump's flange, not that screwed into the block) - then you’re just making things difficult. Much better to use studs or else bolts with a plain shoulder.  Usually I have to buy over-length plain-shouldered bolts or studs and cut part of the thread off - to get the length of plain-shoulder needed.  

Washers :  Firstly a split washer will by definition not seal - it has a split.!  And a plain or dowty washer will not seal if any part of the face is not reasonably smooth and flat - that’ll be the gap between the outside face of the flange and the underside of the bolt head or nut.  This gap needs to not only be flat and quite smooth but also parallel to each other ..for the full diameter of your washers.  From your photo I see that you’re trying to seal a washer on the rough cast finish ..and also very close to the inside fillet between the flange and the sump’s bowl.  

If your cylinder head or any other gasket face had that sort of mountainous texture would you expect it to seal ..why then should these ?  If that corner fillet is holding your washer up at one edge then again it cannot provide a decent seal.   I very often have to bend or file away the rim of a washer to get it to sit flat where such fillets are close to the bolt hole.   NB. Please do not cut a sharp edge into such corners to gain more space ..especially with castings (in any material) as doing that would concentrated stress and may lead to it cracking there. It's a hundred times better to file away the edge of the washer.  However, I do use a round needle file in such places ..but only to remove the projecting / high (casting) roughness out of those corners. Please do not file / cut the corner to a tighter radius.     

Wouldn’t you use a copper or fibre washer of the correct size to seal under something like a screw-in oil pressure sensor, so why use hardened steel here ?  If in doubt, copper washers are cheap enough in the first instance, but otherwise can be re-annealed simply enough with a butane blowtorch each time they are reused. Naturally use washers with the correct inside hole diameter.

A similar problem occurs on a boat's deck fittings, whether they be cleats, fairleads, stanchions or rigging, even though these are bedded in the highest quality compounds.  Again part of the problem is the difference in materials, and also their inevitable flexing, but most commonly because fitters assemble the things and squeeze out all the sealant when they tighten the fastenings down the first time.  The softer material then settles a little with use, and the fitting are not re-tightened before they leak.!   A way around this is - to countersunk either side of the mating face's hole, just a 1mm into each is usually sufficient.  This then gives the sealing compound somewhere to squeeze into and when cured is just like having an o-ring around the fastening. This generally isn't necessary with a car engine (greater thermal expansion but less flexing)  but is easy enough to do so anyway.   

A final note about sand-cast aluminium parts - is that they distort as the molten aluminium cools.  Furthermore as a ductile material - it tends to move when not stored on the flat.  It is very common to find the gasket face, even on brand new parts, to be twisted, sunken or to have hogged a little.  Over the length n’ breath of the gasket face of long sump this might be as much as 1/8”.  Most likely a new part from a reputable dealer will have been machined to a much tighter tolerance than this, but has it always been stored flat.?  A surprising amount of twist can be pulled straight with the fastenings, but less so with a sunken or hogged part.  The way to check this is to refit the sump with sparkling-clean gasket faces and no gasket. Loosely but evenly pinch up all the fastenings, and then to go around to see if a feeler gauge will slip into the crack.

Note : I hope the above does not come across as being too pushy / opinionated.  I apologise if it does.  It’s not nearly as easy to write well-meaning advice as it is to quietly explain some things face to face.  Best regards,

Peter.   

.

 

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Nice post Pete, great explanation and didnt come across as ‘preachy’ at all

 

steve

raising my bet on Gasket to 20p !

Edited by Steves_TR6
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Wow... thank you for such a comprehensive post Peter.. :D

Lots of good food for thought in there.. Interestingly, I did actually buy a sheet of 6mm cork gasket to use for the SAH  aluminium rocker cover as it was a non standard size and I thought I'd need to cut my own gasket. I could try that for this purpose too maybe. Your thoughts on the washers make perfect sense, and it shouldn't be difficult to replace the bolts with studs instead..  I feel a bit of a mini project coming... although, this now definitely sounds like one for post next weekend.. you just know something will go horribly wrong when trying to do stuff on a deadline!! :rolleyes:

Panch 

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14 hours ago, Panch said:

Lots of good food for thought in there.. Interestingly, I did actually buy a sheet of 6mm cork gasket to use for the SAH  aluminium rocker cover as it was a non standard size and I thought I'd need to cut my own gasket. I could try that for this purpose too maybe. Your thoughts on the washers make perfect sense, and it shouldn't be difficult to replace the bolts with studs instead..  I feel a bit of a mini project coming... although, this now definitely sounds like one for post next weekend.. you just know something will go horribly wrong when trying to do stuff on a deadline!! :rolleyes:

I would have thought 6mm cork gasket would be difficult to handle for that size of sump.  Admittedly my old bike engines are much smaller but I think I'd find 1.5mm - 2mm thk. plenty compliant.   I suspect the 6mm stuff might best be used for pressed-steel rocker covers and sumps which have a retaining return flange around the outside edge of them, rather than for alloy covers with no recess.  

I'm not so familiar with the TR6 but have read that ..when the engine is still in the car - the sump drops down slightly and then slides back to be removed.  So please check the amount of space you have to do that - before you fit studs, otherwise you'll be cussing me sometime down the line.   If you don't have a lot of clearance then shouldered bolts, cut off to the correct thread length, ought to work fine. 

Having made yourself a cork gasket with nicely-tight fitting bolt holes - then I think the trick to fitting will be to apply gasket-goo between the bottom of the gasket and the sump's sealing face, and then lay it on that face and insert the bolts (with appropriate washers, etc.) up through the sump's flange and gasket. The gasket should hold the bolts in place, and conversely the bolts will hold the gasket in place - while you offer the whole lot up to the block.

Personally I would leave the top of the gasket dry, or even add a smear of Coppaslip to it.,  so then, as and when the sump is next dropped off - the gasket ought to stick to the sump but quite easily be prised away from the block.  I have a favourite 1" wide and quite bendy decorator's scraper to slip in between the gasket and the block, so I undo the nuts half way and then work my way around easing the gasket away - so that it is re-usable.  

As suggested previously ; when fitting the sump gasket for the first time - I don't tighten it so much as to squeeze the gasket-goo out.  I find it better to just lightly (but evenly cross-diagonally) pinch the bolts up to a very low torque setting. I then leave the gasket goo to set overnight (or longer still) and only pinch them up tight just before I add the engine oil.   

Again I hope that is helpful.

Pete.

p.s. the TR4a  ..I'm still waiting to buy,  had an SAH rocker cover, but the existing owner sold it along with the rest of the SAH bits ..originally fitting back in 1965.  The latter owner's intent was to covert this car into a TR5 ..but he never got around to doing that either.  It's a little sad to have lost those original features but hey.. that was just another episode in the car's history. 

Edited by Bfg
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On 8/9/2019 at 11:17 PM, Bfg said:

.

To be frank I'm rather amazed at the harking-on about a porous aluminium sump, which seem to ignore (..in this instant) the oil would have to defy gravity to get up to the rim, to then run down onto the bolt heads. !   I’m fully aware that turbulent air flow can contribute to this phenomenon but unless the bottom of each of the sump fins have been wiped clean but the bolts have not - then the photo suggest this not to be the case.  

Naturally a soft-compound gasket is used to accommodate any surface imperfection of those mating faces. The higher the manufacturing tolerance and the more stable the mated materials : the less gasket thickness / compliance is required.  For example, a gasket is generally very thin or not required at all during assembly of an oil pump, whereas for unstable and different materials such as a pressed-steel sump and a machined cast-iron crankcase - the gasket will be thick and very compliant.

A gasket's purpose is to prevent fluids moving laterally across a mating face.  And almost always, the hole in the gasket is bigger than the stud or bolt, and therefore there is always a gap sufficient for hot oil under both gravity and crankcase pressure to seep through.  If the hole were not bigger then you'd have to tap the screw thread in through the gasket every time you fitted a stud or bolt. In many instances this 'self-tapping' may occur on one side of the gasket's hole but rarely is it all around that hole ..because manufacturing tolerances of the crankcase’s bolt pattern and the holes through an after-market gasket would not be accurate enough for an interference-fit. 

Similarly, the holes through the sump’s flange must be loose enough to account for any variation in the crankcase’s stud pattern  ..as well as to get the studs / bolts through the sump even when crawling around under a car.   

Furthermore, because aluminium has a different rate of expansion to the cast iron crankcase, design allowance need be made for fitting these at different temperatures.  Of course aluminium sumps and rocker covers fitted to iron engines will always be prone to leak unless there is sufficient allowance for thermal-expansion (..more prevalent on large hollow-shell casting than on smaller components).  In the old days this was usually accommodated by using a thick cork gasket and very low fastening torque. Nowadays card gaskets are made and used ..but only because they are cheap to stamp out and then easy to handle for volume production,  but they are not nearly as stretchy, so as the different-metal parts thermally expand and contract / move relative to one another ..their seal breaks. 

A couple of months ago,  I bought (cheaply available off a well know auction / buy-it-now site) a one-square-metre x 1.5mm thick sheet of cork to make gaskets for a vintage motorcycle, specifically its aluminium sump.  In this case I've used 'Heldite' to bond one side of the cork to the sump. In doing so, I fitted the sump ..evenly but only very loosely (so the jointing compound didn't all squeeze out) to allow the compound to set.  Now fitted and in use ; the other side of the gasket is still without sealant of any kind, and I'm using just 6-ft-lb torque on its fastening nuts. They did need re-tightening after a number of thermal cycles, but they remain oil tight.  

An advantage of thick cork gaskets, over paper and other composite types, is that they are stretchy to pull over sump studs. This means that their hole size can be tight on the stud and yet dimensional tolerances in stud pattern are easily accommodated. They're not nearly so easy to fit when using bolts (rather than studs) but usually it is possible. The additional and great advantage is that cork bulges sideways very much more as it is compressed, so a hole through a thick cork gasket will pinch even tighter onto a fastening stud or screw thread.  

Fastenings. I see in the photo that your sump is fastened with bolts. But I wonder if they have plain shoulders ?  Otherwise you are trying to seal something with a serrated edge. And unless those are thoroughly clean ..and sealant is wiped into those threads before fitting (I'm talking about the bit which is through the sump's flange, not that screwed into the block) - then you’re just making things difficult. Much better to use studs or else bolts with a plain shoulder.  Usually I have to buy over-length plain-shouldered bolts or studs and cut part of the thread off - to get the length of plain-shoulder needed.  

Washers :  Firstly a split washer will by definition not seal - it has a split.!  And a plain or dowty washer will not seal if any part of the face is not reasonably smooth and flat - that’ll be the gap between the outside face of the flange and the underside of the bolt head or nut.  This gap needs to not only be flat and quite smooth but also parallel to each other ..for the full diameter of your washers.  From your photo I see that you’re trying to seal a washer on the rough cast finish ..and also very close to the inside fillet between the flange and the sump’s bowl.  

If your cylinder head or any other gasket face had that sort of mountainous texture would you expect it to seal ..why then should these ?  If that corner fillet is holding your washer up at one edge then again it cannot provide a decent seal.   I very often have to bend or file away the rim of a washer to get it to sit flat where such fillets are close to the bolt hole.   NB. Please do not cut a sharp edge into such corners to gain more space ..especially with castings (in any material) as doing that would concentrated stress and may lead to it cracking there. It's a hundred times better to file away the edge of the washer.  However, I do use a round needle file in such places ..but only to remove the projecting / high (casting) roughness out of those corners. Please do not file / cut the corner to a tighter radius.     

Wouldn’t you use a copper or fibre washer of the correct size to seal under something like a screw-in oil pressure sensor, so why use hardened steel here ?  If in doubt, copper washers are cheap enough in the first instance, but otherwise can be re-annealed simply enough with a butane blowtorch each time they are reused. Naturally use washers with the correct inside hole diameter.

A similar problem occurs on a boat's deck fittings, whether they be cleats, fairleads, stanchions or rigging, even though these are bedded in the highest quality compounds.  Again part of the problem is the difference in materials, and also their inevitable flexing, but most commonly because fitters assemble the things and squeeze out all the sealant when they tighten the fastenings down the first time.  The softer material then settles a little with use, and the fitting are not re-tightened before they leak.!   A way around this is - to countersunk either side of the mating face's hole, just a 1mm into each is usually sufficient.  This then gives the sealing compound somewhere to squeeze into and when cured is just like having an o-ring around the fastening. This generally isn't necessary with a car engine (greater thermal expansion but less flexing)  but is easy enough to do so anyway.   

A final note about sand-cast aluminium parts - is that they distort as the molten aluminium cools.  Furthermore as a ductile material - it tends to move when not stored on the flat.  It is very common to find the gasket face, even on brand new parts, to be twisted, sunken or to have hogged a little.  Over the length n’ breath of the gasket face of long sump this might be as much as 1/8”.  Most likely a new part from a reputable dealer will have been machined to a much tighter tolerance than this, but has it always been stored flat.?  A surprising amount of twist can be pulled straight with the fastenings, but less so with a sunken or hogged part.  The way to check this is to refit the sump with sparkling-clean gasket faces and no gasket. Loosely but evenly pinch up all the fastenings, and then to go around to see if a feeler gauge will slip into the crack.

Note : I hope the above does not come across as being too pushy / opinionated.  I apologise if it does.  It’s not nearly as easy to write well-meaning advice as it is to quietly explain some things face to face.  Best regards,

Peter.   

.

 

Good advice.

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Pete's (aka bfg) advice makes perfect sense.

With regard to gaskets and gasket materials I’d like to pass on the following contact whom I had the pleasure of meeting and competing against on the TR Register Liege Brescia Liege Rally very recently.

John Hicks is the owner of Ram Gaskets – based in Cornwall https://www.ramgaskets.com 

Ram gaskets are gasket manufacturers and gasket material suppliers.

Moreover John is a fellow Triumph enthusiast and drives a beautiful TR4A.

When we got into conversation during the rally I found him very knowledgeable and very helpful.

Check out their web site – they offer technical advice, material samples, bespoke solutions and there is no minimum order quantity.

I will definitely be beating a path to John’s door in future.

Martin

Edited by BritishRacingGreen
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Thanks Pete for the additional info and Martin for the gasket info. Sorry for the delay in responding but I've been putting some long hours in over the weekend and evenings trying to get her ready for Friday.. how is it that a car that's been on the road for only 4 months can need soooo much cleaning!! Admittedly I take her out in all weathers, and we've had a lot of rain this Summer.. but still! With that and all the little snagging jobs, timing is going to be pretty tight. 

Anyhow, will definitely come back to this in the next. couple of weeks once Stratford weekend is out of the way.. :D

Panch 

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7 hours ago, Panch said:

 I've been putting some long hours in over the weekend and evenings trying to get her ready for Friday.. how is it that a car that's been on the road for only 4 months can need soooo much cleaning!!

Friday afternoon : rain forecast.  Saturday 40% chance of rain ..likewise Sunday afternoon. :unsure:   Lots of car wax I'm thinking !

 

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Love the write up Pete,  a lot of helpful information 

I have an alloy sump, baught it second hand, never been a problem,  apart from a slight leak from the drain plug,

I no alot of people are going to disagree, but I always use silicone to fit the sump,  also on the thread of the bolts, (and any item that requires a gasket, )  I use flat washers, lightly bolt it down, when the silicon has gone of I torque it down, 

I no people believe it could break of internally,  and block an oil feed, but this dousnt happen as silicon is really difficult to remove,  I learnt this from an old biker, who helped me with the restoration of old british bikes were there is a lot of movement in the casing, 

Just my thoughts pink 

 

 

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4 hours ago, pinky said:

I know people believe it could break off internally,  and block an oil feed, but this doesn't happen as silicon is really difficult to remove,  I learnt this from an old biker, who helped me with the restoration of old British bikes where there is a lot of movement in the casing, 

Must admit I categorically refuse to use silicon sealant on any engine ..as I've seen the damage directly caused by beads of sealant which have got away ..and then blocked oil ways  ..not just once but on several occasions during the short 18-month period I was professionally restoring vintage motorcycles.   Of course the choice is yours, and I accept the risk must vary a great deal with the design of engine, but the post-war Sunbeam twin has an overhead camshaft and the oil route to that is susceptible   ..and then the replacement cost of cam followers, rocker bearings, camshaft, plus the line-boring and sleeving - tends to make one's eyes water.  

P1070887.thumb.JPG.c1841e525492230de005de423b0d2a6b.JPG

^  indisputable..  the bead of blue silicon sealant in the camshaft's journal. This is my own photo of a so-called 'troublesome engine' subsequent to having been rebuilt by the client's father.  Ironically the engine had been fitted with a new camshaft, so he spent hundreds-of-pounds but tried to save a few pennies (..or minutes).

The (above) oil feed is up through internal crankcase and cylinder drillings to the camshaft journals, and subsequently to the the cam lobes and followers. The oil's course is also to lubricates the bushes within the rocker shaft and then also the valve stems ..also serving to carry heat away.  Oil return is down the cam chain  ..so with no oil getting in - each of these things run dry, get very hot (cylinder head temperatures + friction) and self destruct.  

Is it that the design was poor ?   Personally,  I ride an early model from 1948 and two others from 1953 - each on their original camshaft journals ..so I'd suggest it is not the design but rather the home mechanic who tries a miracle-cure  ..rather than to simply take a few minutes to prepare gasket faces to be smooth, flat and clean.  And then to use the appropriate gaskets (..even if that means hand-making cork ones if they are no longer commercially available). 

My apologies to all  if this is a little off topic, but just perhaps it equally applies to some oil ways in the TR engines.? 

Pete.

p.s. I do however use black silicone sealant as a gap-filling adhesive on non-engine rubber parts.  And I've effective repaired cracked but not split right the way through CV joint gaiters, and similarly to re-make the top part of a gear-change gaiter (which was torn off so did not seal around the gearshift).  And then just the other day I used it to replaced the rubber bushes in the sprung saddle of my early S7.  I bonded new rubber blocks to the steel carriers with black 'engine gasket' silicon sealant.  

 

Edited by Bfg
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