Quote:
Originally Posted by SD1too
Take no notice of a well-known and notorious member's efforts to belittle this simple remedy, should he appear on this thread.
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Hello Digby, while there may be "evidence" SD1too believes to be true that mechanical abrasion is the causal effect of O ring failure, this is a known failure mode on other MGR models employing the exact same O ring as used in the KV6 thermostat assembly, hence invalidating his theory.
For the lowdown on the actual failure mode, you may wish to follow the link in my signature, where you will find compression set is the
actual cause of failure.
For others who may be interested, I have attached the original AR specification and drawing for CDU3858, in order that you may obtain a Viton O ring of the correct dimensions.
I won't bore you with the details, however my background is a electro-mechanical design engineer, specialising in factory automation, and a particular bias in the disciplines of pneumatic and hydraulic control.
Now you can imagine I have seen quite a broad and varied range of mechanical seal failure, and investigated the causal factors in some depth, and O rings suffering from compression set are no longer round in section, instead they appear to be a flattened oval where the material has taken on the form of the groove the o ring is positioned in.
This is the
exact failure mode I have witnessed in many cases of the O ring in question, when employed not only in the KV6, but also the four cylinder K series.
Simon can base his findings on
one car, and as such has a limited subject sample to draw upon, and while he may be correct in assuming the O rings are at fault, he is most certainly incorrect when assuming the failure is caused by mechanical abrasion.
So what it boils down to in the end, do you trust the opinion of a vision mixer who has worked on one car, or the time served engineer who has worked on many more than that.
Brian (The Notorious Member)