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Old 29th January 2021, 11:49   #21
SD1too
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Smile Long answer, sorry.

Quote:
Originally Posted by Dorset Bob View Post
You state that the 'O' rings are the same on both types, so why do they leak on the plastic ones and not the metal?
Hello Bob,

Thank you for asking. I have spent a lot of time carrying out tests on my own engine as well as taking into account evidence from other forum members. It was actually Minimutly who had the idea which led to the breakthrough but I did the donkey work. In order to answer your question properly Bob, I will first explain how the plastic pipe system should work.

The plastic components are obviously lightweight; that was the reason for MGR choosing that material. Minimutly suggested that they can move in service (22.12.15, post no. 17). If the large hose to the thermostat housing is grasped and tugged you might see this for yourself. This movement pivots about the 'O' ring at the base of the thermostat housing which is where the leak occurs as the ring becomes flattened through friction.

In RAVE (26-3-17) it is stated: "Secure coolant pipe with clips". This is, of course, referring to the serrated ("Herbie") clips mounted in channels on the straight pipe. The purpose of these clips was not considered by anyone, including myself, until Minimutly had his idea. So what exactly do they do?

In order to fit the plastic parts to the engine the straight pipe must be able to slide to the right into the thermostat housing such that the other end can be inserted into the water pump. Once this has been done, there is nothing to stop the straight pipe moving left and right when the engine is running. This movement causes friction to the straight pipe's 'O' rings and also rocks the thermostat housing in its mounting causing the same to happen to the 'O' ring at its base. These movements are small but continuous and the long term effect is easy to imagine.

The serrated ("herbie") clips on the straight pipe are there to prevent this movement. Each sits in a channel somewhat wider than the clip's dimension. This enables them to be moved from side to side. When they are fully inwards the pipe is set for assembly. When they are fully outwards, the pipe is prevented from sliding between the thermostat housing and water pump. It is securely fixed in position and the serrated jaws are adjusted to keep it there. This is the purpose of the clips. It is confirmed by RAVE (26-3-17) which states: "Secure coolant pipe with clips". If this procedure is followed, the 'O' rings on the plastic components will not leak.

The reason that people mistakenly believe that the thermostat housing welded seam splits is because pressurised coolant sprays upwards from the flattened 'O' ring and deposits itself around this seam. I have proved this by refitting the following housing to my engine with only a new 'O' ring and the leak was cured! No-one else has had the conviction to do this.



Thanks for your patience so far Bob. Now I'll come to the crux of your question. The reason why the same 'O' rings on Kaiser's metal components don't leak is because the cast aluminium is inherently heavier and much more rigid than the plastic and so successfully resists any movement. The 'O' rings on his parts therefore don't suffer any friction. It should be noted that one disadvantage of Kaiser's system is that it uses an 80 degrees thermostat so the engine will run about 10 degrees too cool. The parts are also expensive to buy when all that is necessary is a set of 'O' rings and an adjustment of the serrated clips.

Sorry that this is such a long reply. I know that some aspects of it have been challenged on theoretical grounds, but the proof of the pudding is in the eating and my engine has been leak-free for several years now so I think that speaks for itself.

Simon
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Old 29th January 2021, 19:19   #22
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The o rings flatten as a result of compression set, this has nothing to do with abrasion.

Abraded O rings display striation marks, ones suffering compression set have simply lost the ability to seal due to a degrading of the elastomer compound.

The same O rings are used in the K16 thermostat which is bolted rigidly to the block, and these suffer the same fate without any aspect of movement other than thermal expansion.

Empirical evidence based upon one car does not constitute an answer to the problem of KV6 owners, and the theory of movement has already been debunked by another KV6 owner who followed to the letter the advice regarding the positioning of the clips on the straight pipe.

Simply put, you can take your pick as to which theory is right, it's been covered in great detail in past threads on the subject.

Brian
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Old 30th January 2021, 19:28   #23
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New evidence from two other owners supporting my movement explanation has just been posted here.

Simon
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Old 30th January 2021, 23:33   #24
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New evidence from two other owners supporting my movement explanation has just been posted here.

Simon
Any advice for Rob then Simon?

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Old 31st March 2021, 08:27   #25
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Hi guys,

Whilst waiting for the metal thermostat to arrive took off the inlet manifolds and surprisingly I could find nothing wrong with the thermostat or its connections. The inlet manifold gaskets looked fine so I am at a loss as to understand where the coolant is leaking from. Could it be that the seams of the thermostat are expanding when the engine gets hot?

Anybody got any ideas please?

Martin
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Old 31st March 2021, 11:47   #26
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Quote:
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... I could find nothing wrong with the thermostat or its connections.
Hello Martin,

Were the 'O' rings flattened?
Back in January, was your engine leaking coolant into the 'V'?

Simon
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Old 31st March 2021, 16:33   #27
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Hi Simon,

The "O" rings are not flattened and there was coolant in the "V". I really am at a loss to understand where the coolant leak is coming from.

Any ideas?

Martin
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Old 31st March 2021, 20:56   #28
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Quote:
Originally Posted by Mr Toad View Post
Hi Simon,

The "O" rings are not flattened and there was coolant in the "V". I really am at a loss to understand where the coolant leak is coming from.

Any ideas?

Martin
Just curious and poking my nose into this thread. Are the rings definitely the right diameter and are you sure they are being compressed ?? They should stick some way out of their groove before the housing is being tightened down.
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Old 1st April 2021, 06:23   #29
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The "O" rings are not flattened and there was coolant in the "V". I really am at a loss to understand where the coolant leak is coming from.
OK Martin, so the coolant level in the expansion tank is going down but you've seen no external evidence of loss; have I got that right?

Can you refresh my memory please:
  • By how much is the level dropping in a given time?
  • Is your fan working?
  • What's the normal running temperature on the digital display?
  • Have you replaced any parts in the cooling system?

Simon
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Old 20th September 2021, 08:03   #30
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The conclusion to Mr Toad's problems is here.

Simon
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