Series 2 what should be the compression test readings on a 2a petrol

ronsealdeath · Dec 13, 2015

Forget book psi figures, you cant replicate the conditions land rover tested under so your readings on a diy gauge will be way off even on a healthy engine. So just go by the fact compression is more than 10% lower on one cylinder then try with oil in comp chamber to check ring wear. But have you tried a new plug and lead on that cyl? A plug firing in the environment of a combustion chamber with fuel air mix flowing over it isnt like a test in air. You can only rule spark out by replacing plug and lead in this case. It sounds to me like one is failing under running conditions.

divie · Dec 14, 2015

I am hearing of lots of fake NGK plugs on the auto jumble circuit. Had mates chasing non or poor starting bikes. New genuine plug and all was well.

peter8315 · Dec 14, 2015

just waiting for a head gasket delivery and will pop the head back on and like you say ronsealdeath, its got to be some thing along the spark line, but will look into that when got head back on, and will keep you posted as to any further developments

Dippypud · Dec 14, 2015

divie said:
I am hearing of lots of fake NGK plugs on the auto jumble circuit. Had mates chasing non or poor starting bikes. New genuine plug and all was well.

Years ago Champion spark plugs, then the market leader, had the same happen ... cheap nasty Spanish made plugs, more failed than worked ...

Dippypud · Dec 14, 2015

ronsealdeath said:
Forget book psi figures, you cant replicate the conditions land rover tested under so your readings on a diy gauge will be way off even on a healthy engine. So just go by the fact compression is more than 10% lower on one cylinder then try with oil in comp chamber to check ring wear. But have you tried a new plug and lead on that cyl? A plug firing in the environment of a combustion chamber with fuel air mix flowing over it isnt like a test in air. You can only rule spark out by replacing plug and lead in this case. It sounds to me like one is failing under running conditions.

Compression can also be lost through the valves and valve seats if they are not sealing well ... common in older engines run on unleaded petrol without lead replacement additive ...

peter8315 · Dec 17, 2015

Well, put head back on today, without really doing much to it, started it up and bingo, she run's sweet as a nut, and dare i admit it, i think i had the firing order wrong, i was working on the rota arm going clockwise, and checked today and its anti clockwise, so ill put it down to a senior moment, that cost me a lot of stress, thanks all for your input

jamesmartin · Dec 17, 2015

peter8315 said:
Well, put head back on today, without really doing much to it, started it up and bingo, she run's sweet as a nut, and dare i admit it, i think i had the firing order wrong, i was working on the rota arm going clockwise, and checked today and its anti clockwise, so ill put it down to a senior moment, that cost me a lot of stress, thanks all for your input

weve all done it ,but main thing is it running ok now and youve fixed it yourself

Edlandy · Dec 17, 2015

Well done for sorting it out!

tottot · Dec 18, 2015

Well done,just don't get a V8.

honolulujoe · Dec 18, 2015

excellent, time for a cigar

chris7 · Dec 18, 2015

Be interesting to know what your compression readings are now?

peter8315 · Dec 21, 2015

funnily enough that was the first thing i did, and they still read around the 80psi mark, but it runs like a dream now i hav'nt took it out yet as got to put wing back on, but will report back

Series 2 what should be the compression test readings on a 2a petrol

ronsealdeath

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divie

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peter8315

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Dippypud

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Dippypud

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peter8315

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jamesmartin

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Edlandy

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tottot

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honolulujoe

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peter8315

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