Expansion Tank Caps - Do Not over tighten

I've been through 3-4 R53 expansion tank caps now in 3 and a half years that kept leaking. Sometimes I couldn't see the leak, sometimes I couldn't, but I continually had to keep topping up.

This happened again a few months ago and for the fist time, I decided to actually look inside the cap. The attached is what I found.

Clearly I've over tightened the cap, which in turn has distorted the seal to a point where it would not hold pressure, perhaps causing the fluid to boil and then escape past the damaged seal. Or like a kettle, it would lose water through steam. Either way, I was continually losing water.

Since realising this, I've been very careful when tightening and never had to top up again.

Just thought I'd share this in case anyone else was suffering the same issues.

http://uploads.tapatalk-cdn.com/2017...2f79d3dccd.jpg


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Interesting read John [emoji106][emoji2]


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Very interesting John

Handy tip that people can use :thumbs up:

Will check mine today (assuming the R50 is the same fitment) :thumbs up:

I think the R50 operates a different system, I seem to remember the expansion tank doesn't have a pressurised cap


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Quote:

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Originally Posted by jdl_1967

I think the R50 operates a different system, I seem to remember the expansion tank doesn't have a pressurised cap


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Having checked today the cap certainly looks similar and the tank is defo pressurised as the last Highland Tour demonstrated :frown:
Good to have a check though :thumbs up:

Good tip.

I've got a persistent coolant leak in my van (which nobody can trace so far...) so very familiar with the coolant cap on that. It has a definite 'stop' were it's impossible to tighten the cap past. Seems a simple solution to prevent over-tightening.

The R50 expansion tank cap is a flip-up lid, rather than a screw-down one like the R53