Vehicle & Technical > Series Land Rovers

Yea olde Parrafin Test.

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carbore:
The parafin test also does not take into account that things expand on a running engine due to heat so tolerences will change. Id never heard of it before and to be honest im glad!

bob86:
You do it on valves to check the seal on the seats.

BeJay:

--- Quote from: bob86 on January 12, 2008, 19:01:32 ---You do it on valves to check the seal on the seats.

--- End quote ---

.....Bob's right, I've never heard of doing it to check the bores, it's bound to leak out reasonably quickly.

......what you do is turn the head upside down on the workbench, put a block of wood etc under each end to make it sit level and then fill the combustion chambers with the parrafin. ideally it all stays there, (perfect seal on valve seats) the faster it leaks out then the worse the seal is.

Range Rover Blues:
I've heard of doing a leakdown test with compressed air (on a complete engine) that tell you where the leaks are, but you're going to get some otherwise the engine would be so tight it wouldn't turn over.

Remember also that Aluminium (pistons) expands at twice the rate of Iron and steel (block/bore) so when cold nothing fits.  The pistons will probably be ground oval because they expand differently on the 2 axis, because of the skirt and the gudgeon pin.

I'd fully expect the parafin to be gone overnight, if it stayed for an hour I'd be surprised.

A compression test is a time-honoured test for basic engine soundness and that's what I'd recomend.  A leak down test 9still saving for the tester) is a step beyond that.

Oh yeah, and then there's capiliary action.  I won't bore you with details but if you think how a fountain pen works, 2 surfaces close together will draw a liquid in between them and conduct it under gravity.

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