Oil leaks around the front of the engine (850cc Mk2) at head gasket level are wearing me down.
It got so bad on the right side of the engine that I sent the head to Norman White who found a crack using die penetrant which was fixed in Fareham using Laser welding. The leak has now disappeared from the right hand side and reappeared on the left!
I spend more time taking the head on and off than I do riding the bike. I know there are a multitude of other reasons why heads leak but at this stage in the game I really feel I need to know the head it's self is sound.
With this in mind - has anyone ever x-rayed a head? Is this the best way of thoroughly checking it for porosity and cracks etc? Is it mega expensive to do? Is there someone who specialises in this sort of work.
All thoughts gratefully received.
John Cowie
Yes, but expect to pay for…
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I should think it unlikely…
I should think it unlikely that x-rays will pick up a crack. They are good at picking up defects in (for example) welds where holes (porosity) exist inside the material so the aggregate thickness is locally different. A narrow crack is not like this. There are ultrasound methods. These work where the surface is smooth so there is somewhere for a probe to sit. That might work if the probe is used on the joint face if the crack returns an echo from something closer than the complicated top face. Could be worth a try.
Dye penetrant, as used before, is probably best. Unfortunately aluminium is not magnetic so it cannot be enhanced magnetically as it can with steel. Very close visual inspection of polished surfaces is usual for aluminium but as you know that's not easy.
I think I would consider ultrasound.
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A short ride with the rocker…
A short ride with the rocker feed blocked off will tell you if the leak is from inside the head or coming up through the barrel via a stud. Then you have a better idea of what the next step is.
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.....from someone in the industry....
I've just phoned a company specialising in x-ray inspection and was told that, because of the awkward shape of the cylinder head and the fact that you have to focus the x-ray on a certain cross section it would be necessary to do multiple 'takes' and it would cost a fortune.
he recommended gamma testing as a better option but, again, very expensive.
By the way, he wasn't surprised that fixing one leak just pushes the problem to another area!
He says the traditional way of detecting porosity was to put the part in a vacuum chamber, immerse in a fluid and this causes areas of porosity to show when returned to atmospheric pressure.
I think I've heard of someone curing porosity problems using a similar technique. Any thoughts??
Cheers - John
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Porosity and cracks are very…
Porosity and cracks are very different - do not confuse them or think a cure for porosity will cure a crack. Porosity can be dealt with using Ultraseal, and it will seal a large gap. A crack it will fill, but you need to ensure the crack is not live, if it is then it will still leak post sealing.
The latest X-ray machines about to come into use have some excellent resolution, think of laser scanning from the inside where you can't see.
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The cure is to repeat the…
The cure is to repeat the detection process but using a different fluid which will cure inside the porosity and not come back out when the pressure is released and so filling the porosity hopefully permanently. The Factory used this process but in your case, if you now have porosity, it either has failed or no porosity was detected at the time and no process was applied.
https://www.youtube.com/watch?v=71HP_yAbEiw
But the first step is to identify the issue, as Ashley says, is it a crack or porosity.
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Yes, but expect to pay for an hours labour. There are numerous companies in the UK who do it. Get a video X Ray of the head, if it can spot a crack I don't know.