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IN view of this problem, would it be beneficial to relocate the oil cooler and/or add some sort of forced-air fan cooling? The only place you could put it would be on the outside of the vehicle I would think, it would be ugly but effective. Perhaps one could find a place forward of the engine, there seemed to be a lot of room under there (at least while it is on stands there is a lot of room, maybe not so much when sitting on its wheels...) Stephen J. Jackson Commissioning Engineer, Petron Industries, Inc. SJackson@petronworld.com 71 Fasty -----Original Message----- From: Constantino Tobio [mailto:ctobio@gmail.com] Sent: Friday, November 11, 2005 12:10 PM To: type3@vwtype3.org Subject: Re: [T3] Stretching valve stems? Jim Adney wrote: > >At any rate, here's the question: Do valve stems sometimes actually >stretch before they break? > > I had always heard that a stretching #3 exhaust valve is a sure sign that your vehicle is experiencing a chronic overheating problem. This is why some folks actually track the amount of adjustment they need to perform on their valves- as an indicator of cooling health among other things. #3 and #4 (#3 in particular) are in the more delicate side of the cooling system owing to the location of the oil cooler, so they're the canary in the coal mine, if you will. It intrinsically makes sense to me that there would be forces at play that would stretch the valve if the metal got hot enough. You have a spring acting on the top of the valve stem, pulling the bottom of the valve against the seat. The metal gets too hot, the stem could stretch. In a properly functioning engine, this shouldn't be as pronounced, but in an overheating engine, all bets are off. In my brain, I also envision that as the valve stem gets longer and longer, it's getting thinner and thinner (think stretching taffy, only not as tasty), and the metallurgy is changing significantly and getting weaker. I would think that a valve shouldn't break without warning (unless there's a metallurgical problem)- the valve stem should indeed be stretching before that happens. If you adjust the valves at the prescribed interval, you should notice this. I've actually heard this from people in the Type 1 world, especially on pre-doghouse cooling shroud engines, but I see no reason why it wouldn't apply to any aircooled engine of that heritage, including our T3s and even T4s (presuming the oil cooler is in a similar location and the cooling setup is the same) Certainly I defer to people with a lot more experience than me- this is just my opinion. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~