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Discussion Starter #1 (Edited)
Hello,
I from Poland. Sorry for my english language
does anyone know the size of the front sealant from the coolant tube? or what it suits. it has been discussed so many times but nobody has ever measured this front gasket. I need it terribly but it is not available in Poland
 

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I do not know the size but if you are trying to replace just the o-ring seal on the transfer pipe/coolant pipe it will take a tremendous amount of work. You will want to use an aftermarket transfer pipe/coolant tube from URO or AGA. Most people cut out the old pipe.


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If you're talking about the rubber disintegrating into the joint roughly 2" (50mm) past the water pump mounting face, I believe it's a complex thick rubber gasket that seats the coolant transfer pipe's problematic front seal. As BabyUnicornTaco mentioned above, replacing it as original is a huge task requiring engine disassembly as it's not really an internal o-ring as might appear from the broken bits falling in. There are a few less-invasive ways to fix it, though, apparently including after-market collapsible coolant transfer pipes and stents. I'm trying to do a DIY sleeve to an N62 coolant transfer pipe that might have had a previous repair. For inspiration (funny how similar situations occur in completely different fields sometimes), I recently rebuilt a circa-1990s Aquanetics Q8SPT UV-C hot-cathode germicidal water sterilizer for my aquarium (since the newer cold-cathode units are too inefficient at the key 254 nm wavelength), which did have such internal o-rings, where the quartz tube acted as a sealing sleeve. Since the o-rings have been no longer available (NLA) for many years, one fix (which I can't recommend due to the fragile quartz sleeves becoming NLA) has been sealing with 100% RTV silicone (although I think an automotive application shouldn't require pure and might even benefit from high-temperature additives).

Just removed water pump due to a serious coolant leak on my better half's recently acquired E53 X5 (actually "MX5" per rear emblem, whatever that means) 4.4i with N62 engine, and noticed not one, but two joints in the front of the coolant transfer pipe. The first is about 2" deep from the mounting face and the second is about 4" deep from the mounting face. The joint at 2" depth had bits of broken black rubber protruding inwards, so my guess it that's probably the leak source (since water pump seems to be a fairly recent high-quality metal-impeller with no discernible shaft play), while the second front joint at 4" depth has no rubber showing at all but is obviously misaligned upwards by about 2-3mm compared to the next section. If the 2" deep joint is the normal timing cover to coolant transfer pipe joint, what could the 4" deep misaligned joint be (or do I have them mixed up)? After removing the bits of broken rubber, a 1.2" o.d. socket just barely clears both joints while a 1.3" o.d. socket won't even enter the hole. Current thought is to pick up a piece of thin-walled aluminum alloy tubing (I'm thinking 6061 or 6063 about 32mm o.d., 30mm i.d. to minimize flow restriction, 4-5" long, if I can find it in Montreal on a Saturday, cut at maybe a 45 degree angle towards the inner end bottom to re-align the sections during insertion) to both sleeve and stent both joints. But why do I have two joints rather than just one? Is there a known repair that might already have been applied that could have added the second joint? If so, should I use a shorter tube (say 3") to avoid overlapping the second joint (but leaving the misalignment as-is)? Any/all hints and/or links appreciated. Truth be told, I'm still hoping to borrow the X5 to tow my ice racer to the lake and back this Sunday.
 
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