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Author: Subject: Compression test?
coozer

posted on 11/8/17 at 01:27 PM Reply With Quote
Compression test?

What's the best why to test compression on an oil dry engine?

Basically my v8 has been sitting for a few years with the sump and inlet off, no cam or front cover.

Now I want to know what the comp is like before I build it back up in case I do need to remove the heads...

Flywheel and starter are on it and I'm ready to go......





1972 V8 Jago

1980 Z750

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mcramsay

posted on 11/8/17 at 01:49 PM Reply With Quote
I would say you could not do a compression test in this state, you would need to put the sump on and fill with oil. You could however carry out a leak down test on each cylinder by turning to TDC by hand. This would show any leakage paths in the valve train/ rings that would affect compression. I would put some oil down the bores and on the crank and let it soak before turning if it has not moved in a while
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britishtrident

posted on 11/8/17 at 02:00 PM Reply With Quote
Best way woulsd be a cylinder leak-down test, you will need a compressor, old style leak-down testers work at either 100psi many chinese ones now work at only 1bar and will work with a 12v tyre inflator compressor. The dual gauge type are best the ultra cheap chinese ones usually work Okay --- put will need some light oil down the bores and turn the engine over a few times to getting the rings sealing before you test . Redex or Injector Cleaner or Dexron II Transmission work even better than oil.

[Edited on 11/8/17 by britishtrident]

Youtubes from the usual suspects
Paul "ScannerDanner" Eric O at SMA and Matt at Schrodingers Box







[Edited on 11/8/17 by britishtrident]

[Edited on 11/8/17 by britishtrident]





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coozer

posted on 11/8/17 at 02:40 PM Reply With Quote
Thanks, don't have a leak downer, all I was thinking was a sanity check to see if there was any massive callamerty waiting in one of the cylinders..





1972 V8 Jago

1980 Z750

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britishtrident

posted on 11/8/17 at 03:31 PM Reply With Quote
quote:
Originally posted by coozer
Thanks, don't have a leak downer, all I was thinking was a sanity check to see if there was any massive callamerty waiting in one of the cylinders..



Look at the prices on ebay --- the chinese ones are seriously cheap or you could just put low pressure air into the cylinder via a restrictor and listen to where it comes out.





[I] What use our work, Bennet, if we cannot care for those we love? .
― From BBC TV/Amazon's Ripper Street.
[/I]

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gremlin1234

posted on 11/8/17 at 05:53 PM Reply With Quote
quote:
all I was thinking was a sanity check to see if there was any massive calamity waiting in one of the cylinders..
maybe also look with a borescope/endoscope. (camera on a stick)

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coozer

posted on 11/8/17 at 06:04 PM Reply With Quote
quote:
Originally posted by gremlin1234
quote:
all I was thinking was a sanity check to see if there was any massive calamity waiting in one of the cylinders..
maybe also look with a borescope/endoscope. (camera on a stick)


Lol... havent got one of them either! But was thinking of getting a slim one to see what state my ears are in..





1972 V8 Jago

1980 Z750

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coozer

posted on 11/8/17 at 06:17 PM Reply With Quote
Thanks for the suggestions fellas, just done a bit on the bay and now waiting for a leak down kit and an endoscope..

If neither are any good yous owe me 29!





1972 V8 Jago

1980 Z750

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coozer

posted on 17/8/17 at 08:26 PM Reply With Quote
Leak down tester arrived this morning. By dinner time Id managed to break the second gauge so swapped them over...

Chucked up the need for a set of rings and 4 valves not seating correctly, 2 inlets down 30% and 2 inlets down 2%..

Heads are off now and all 8 pistons n rods are in a cardboard box unlikely to be going back in!





1972 V8 Jago

1980 Z750

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