Engine Sealer (external)

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KennyN

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Me - BMW 440i Coupe / Dog -Cayenne
As above knowledgeable people.

The six pot diesel has a slight oil leak coming from the LHS of the bellhousing area , running to the lowest point (obviously) and pooling on the undertray . It is nothing major but i would like to fix it if possible.

The pic below shows the rear of the motor and potential problematic area .

Inkedoil leak 2_LI by Kenny Niven, on Flickr

From what i have researched It seems to be quite a common problem with the diesel Cayennes / Q7`s + Toureag`s and it stems back to engine assembly and the lack of sealant at a certain point around the casing , the later models seem to be OK.

The "fix" from the main dealer is around £8k , Porsche Specialist between £6 - £7k due to the fact that the complete drivetrain has to be dropped to split the engine / trans to repair the problem area which requires allsorts of specialist tooling and is very labour intensive hence the above pricing and not a DIY job.

I cannot claim my Platinum + warranty as it does not cover know manufacturing defects , which it is.

The car (at eight years old) is obviously outwith the manufacturers warranty.

The purchasing dealer have been great at fixing a few issues i had with the car but i doubt if they would entertain this level of repair for what is essentially a small oil leak on an eight year old vehicle and i don`t want to reject the car as apart from this issue it ticks all the required boxes i had prior to starting my search.

So to the question , eventually , - is there a decent recommended sealer that i could use to effect a repair from the outside once i accurately pinpoint the source. It doesn`t seem to be under pressure so that isn`t a consideration and the housing area is quite accessible as once the suspension is set to off road i can get under the car quite easily.

Thoughts ?

K
 
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You could try squeezing something like hylomar blue in there if you can get it clean for long enough but it’s probably just going to keep leaking :(
 
I have used epoxy putty to fix below-the-waterline leaks in a boat....
 
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I was thinking along the lines of some kind of specialist silicone based sealer , something that would stick to the alloy casing and offer some level of sealing properties.

Not bothered if i need to do it every six months or so as once i pin-point the source it should be quite simple to re-apply.

K
 
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I have used epoxy putty to fix below-the-waterline leaks in a boat....

That is the type of thing i am looking for , it is just knowing what will give the best result for the chosen application.

K
 
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..I don`t want to reject the car as apart from this issue it ticks all the required boxes i had prior to starting my search...


Very tricky situation. If this is the case, then it looks like you'll just have to live with the oil leak. Not ideal.

I have dealt with many oil leaks over the years... using various types of sealants etc. But my experience is that no amount of external sealant will work for more than a few weeks. Sorry to be the bearer of bad news.

That said, if you can identify the exact location of the leak, you can try and use RTV sealant for automotive use, though it won't last I'm afraid.
 
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I had very good results in general with GM (Vauxhaull) RTV, but in essence any make will do, e.g.:

pic-6620076308545047814-1600x1200.jpeg
 
Essentially this is a gasket compound, used externally on the engine. The area will need to be dry before applying the RTV sealant.
 
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This is my personal favourite RTV sealant:

 
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That said, if you can identify the exact location of the leak, you can try and use RTV sealant for automotive use

Depending on how accessible the source is then i may be able to set about the joint with my Dremmel to create a small groove which i could fill with an epoxy type of filler. I know there are new products coming onto the market all the time so i was just wondering if there has been something new that may do the job.

K
 
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Depending on how accessible the source is then i may be able to set about the joint with my Dremmel to create a small groove which i could fill with an epoxy type of filler. I know there are new products coming onto the market all the time so i was just wondering if there has been something new that may do the job.

K
My experience is that epoxy-based resins don't do very well with oil and heat. The hardened epoxy resin becomes brittle and separates from the metal. As said, I had the best results with RTV, even though it didn't last for very long either.
 
I was thinking along the lines of some kind of specialist silicone based sealer , something that would stick to the alloy casing and offer some level of sealing properties.

Not bothered if i need to do it every six months or so as once i pin-point the source it should be quite simple to re-apply.

K

Dirko products are as good as it gets I suspect


I've used the 'gray' with good results (it's the typical RTV sealant and is very tenacious).
With a thorough clean and a 'key' it's probably the best chance for a 6 month cure.
 
Is that a complicated engine or what ? so many chains on it ..These are getting more and more complicated .And with more parts to go wrong in them. . Good luck
 
I would be more inclined to try something along the lines of a non setting jointing compound. I think RTV would just start peeling in no time.
 
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I would be more inclined to try something along the lines of a non setting jointing compound. I think RTV would just start peeling in no time.

Yes it will, eventually.....
 
Watch this on youtube video > Permatex Spray Selant Test Oil Leak < -----. There is another repair on there done by putting vacuum to the engine so it sucks the selant in to the cracks .
 
The issue isn't with the oil and heat as such, because RTV resists both and in fact is used on gaskets. Instead, the issue is that RTV is pliable and does not resist pressure very well. When the RTV is applied on the outside of the engine, the oil on the inside is under pressure and will push against the RTV, eventually dislodging it. You would think that epoxy resin will be a better fit under these circumstances, and this is correct in essence because it hardens, but then epoxy isn't very good with the heat and oil and will become brittle and fail.

After many years I have sadly come to the conclusion that the only way to fix an engine oil leak is by doing it properly. Not for lack of trying.........
 
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Thanks for the input people , been scouring YT and Google for some ideas.

I will be borrowing the Endoscope from work tonight and setting it up on an old laptop so i can pinpoint exactly the source of the leak , once i determine where it is i will then make a call as to my plan of attack which will be based on how accessible it is.

A light smearing of JB Weld may be an option as i have watched / read some positive reviews of the product , providing you can "key" and prep the area properly prior to application.

K
 
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Try this:


LOCTITE SI 5699 is a water/glycol resistant gasketing product, ideal for use on flexible flanges, machined or cast surfaces, metal or plastic.
LOCTITE® SI 5699 is a flexible silicone sealant and cures on exposure to moisture in the air to form a tough rubber gasket. The product is designed primarily for flange sealing with excellent oil resistance or rigid flange sealing for example on transmissions and cast metal housings. It is tack-free after just 10 min. The product is water-glycol resistant and can be used on machined or cast surfaces, metal or plastic.

I have a Small Bead of it Around an Inch Long at the Base of the Cylinder on my Triumph T150V, that has been Oil Tight for about 25 Years! :D

Que Jokes about Triumph Oil Leaks! 🤔:oops:🤭;)
 

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