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Issue 321 Forum focus teaser


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Hi, looks like a home made cylinder leak tester, made one my self about 40 years ago.

Set cylinder to TDC on the firing stroke, put in gear and chock wheels if needed, screw the spark plug adaptor in to the chosen cylinder and connect up your air line.

Listen for air leaks out of the exhaust, carbs, crank case and also water or bubbles out of the radiator to indicate if valves, head gasket or rings are worn or failed.

 

Mark 

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The rope trick also works for that if you don't have a compressor.  Remember which cylinder you've moved the rope to though - see my post ages ago to see how I know :wacko:

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TRaction arrived today. I had not realised that the item in question was the one I made !!!

Yes made it to find out where my lost compression was going on No. 3 cylinder. Turned out it was rushing past the closed exhaust valve.

Now all fixed.

Bob.

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  • 4 weeks later...

I just opened up TR Action 321 and I hav'nt seen one of these devices for years.  Peter has the answer I think, I once owned a five cylinder Audi GLS which was prone to worn valve seals with a few miles on the clock.  Characterised by clouds of blue smoke in the mirror when you take your foot off the accelerator.  Loaned one by a Porche 924 owner with the same basic engine, yes its for changing valve seals without removing the cylinder head, and it works. 

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As a matter of interest how much pressure do you need to be able to renew the valve stem seals, to compress the spring enough to get the collets out? I suppose you would have to keep flow/pressure there regulated by the compressor.

I had thought of using the rope method, so don't have to take the head off.

John

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Should be able to work it out - knowing the surface area of the valve head & the strength of the spring.

if spring required 10 lb to compress it enough to release the collets & valve area was 1sq" then 10 PSI would hold it.

Bob.

BUT THAT IS NOT WHAT THE TOOL WAS MADE FOR !!!

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Sorry Bob, you are not trying to use the air pressure to resist the force needed to compress the springs. That force goes through the head. The air pressure is simply to resist gravity and stop the valve dropping into the cylinder. 

Rgds Ian

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Sorry Ian :ph34r:  Knowing how the collets tend to stick in position until disturbed, when you depress the valve spring end cap it will want to take the valve with it even ignoring gravity, so applying enough pressure under the valve head to resist the spring should hold it up.

Bob.

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It is possible using an old plug with the centre cut out & a rod inserted with the end bent over enough to lock behind a valve

& then pulled back holding the valve head shut & then clamped in position to remove the valve spring without removing the head.

I have a home made tool somewhere in my toolbox that that has helped me at race meetings in the past to replace broken

valve springs.

 

                                     Harvey S. Maitland 

 

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Just had a search in my stores & found the tool in question. The rod I used was an old push rod with last inch bent

at approx. 30", have used it on MGBs should work o.k. on TR heads.

 

                                    Harvey S. Maitland

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