Twin port oil cooler adapter seal issue

[Moseley]

Evening folks,

I’ve (yet again) got our engine out to cure an oil cooler seal leak, that has manifested itself recently by spraying a reasonable amount of oil around the engine bay during the hot weather. The lower two seals were weeping when we bought the bus, and I subsequently changed them a few years ago. Unfortunately, they continued to weep.

So either I’m doing something wrong (sealant type perhaps?) or I’m victim of poor quality parts.

Firstly, this is the cooler mount upon removal a it is pretty clear to see where the oil has been escaping from the right hand side of the right hand seal as looking at the photo (the yellowy stuff is the non-setting sealant that has weeped from the seals):

Secondly, this is the imprint that the seals have made on the block (one is quite offset) and of the port on the mount that seems to be causing the issue.

To those that are familiar with these, does the mount look normal? The oil way being at an angle I guess can’t be avoided, but the machining doesn’t look very central, and I think a combination of both these things is causing the seal to distort when torqued down and therefore leaking oil. I’ve no issue with buying a new one, but if they all look like this then I’m wasting my time and money!

Any pointers welcome!


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[Dci_Carter]

I used something like this

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[Moseley]

I used something like this

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Stag Wellseal was what I was advised to use, but the more I think about it / look at my photos, the fact that it has ended up between the metal faces suggest that it is maybe a little too thin for the tolerance their.

To be honest, I’m a big fan of Hylomar Blue for places needing some form of liquid gasket. As it is non-setting, I find it a lot easier to clean in future than silicone type sealants, as these always leave little traces that have to be carefully scraped off. Horses for courses I’m sure when it comes to sealant products! Maybe some fresh seals and a different product might be enough to stop my leaking?


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[K@rlos]

A thin smear of Loctite Si 5980 with decent seals and it won’t leak.

Hylomar is horrific stuff, many better options on the market.

 

[Moseley]

A thin smear of Loctite Si 5980 with decent seals and it won’t leak.

Hylomar is horrific stuff, many better options on the market.

From what I’ve seen, there are only one type of seal on offer - are there vendors out there who sell different options? I have noticed that the leaking one feels a little harder than the other.

Any reason why you wouldn’t recommend Hylomar Blue?


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[K@rlos]

A thin smear of Loctite Si 5980 with decent seals and it won’t leak.

Hylomar is horrific stuff, many better options on the market.

From what I’ve seen, there are only one type of seal on offer - are there vendors out there who sell different options? I have noticed that the leaking one feels a little harder than the other.

Any reason why you wouldn’t recommend Hylomar Blue?

I always use Erling gaskets, even if I need just a cooler seals I buy a complete set as the individual seals are like you say hard. The oil cooler seals in the erling kits are softer, compress and seal better.

I find It messy, can’t be accurately applied and in my experience it never really lasts that long.

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[Moseley]

Well this one has reared it’s head again, lots of oil spray after not many miles last summer. Here is what was found as I separated the parts:





Please feel free to say otherwise, but no amount of sealant was going to stop that seal deformation, and I think that the softer red seals have actually given way easier than the black ones - not slating the seals, more that they are easier to deform if something else isn’t right.

Obviously I’m keen to avoid this happening again, so I’ve turned to the adapter again and bought an original used one for comparison. See some photos below where I’ve tried to centralise the camera over the troublesome port.

Aftermarket leaky one:



OG VW:



As I really want to narrow down the issue, I have taken measurements to compare the various recesses for the seals. The depth of the sealing face (which I assume is the wider part of the stepped seals) on the block side of the adapter is 1.9-2.0mm on the aftermarket, and 2.3-2.4mm on the OG. Using these values, I thought I'd compare it to the same space between the aftermarket adapter and the oil cooler, as I've never had any problems with the seals leaking here. Interestingly, the sealing gap is 2.0-2.1mm, so it would suggest that the issue with the leaking one is not because it is being compressed too much (i.e. the available recess is too shallow). I should add that the depths available for the inner part of the stepped seal are all larger or equal to the seal itself, so I don't think this is causing the seal to shift as it is tightened down.

So that leaves me with the differences with the bore itself. The ovalised bore is never going to be ideal with a round seal, but the photos (and measurements) show that the aftermarket bore is narrower, and is certainly not as centralised as the OG. There is a full mm difference in diameter when measuring the round ports. I'm convinced that the combination of both of these factors is pinching the seal as it is tightened down, rather than just reshaping itself into the bore of the adapter.

Whilst I appreciate the comments previously regarding using a setting sealant rather than Hylomar, in the interest of experimentation, I'm going to take a gamble and again use the Hylomar, but with the OG adapter, and see if the problem goes away. I'm keen to find the root cause, and if there is still an issue, then it'll only be the third time of engine removal to try and solve it!