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Little Megger
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Discussion Starter · #1 ·
Hi All, need to check the compression of my TDCIi, can anyone recommend a pockt-money-priced suitable gauge,I understand I should be getting 200psi on a good day, thanks!
 

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A diesel engine should be a lot higher than 200psi.

The compression pressure can be calulated from atmospheric pressure X the compression ratio of the engine.

Atmospheric pressure is 14.5psi and a diesel engine is typically 20:1 compression ratio.

Hence 14.5 x 20 = 290psi. You tend to end up with a lower pressure due to the rstrictionof the air intake.

Petrol engine testers are quite cheap, screw into the spark plug hole. I have a gunson one, cost about £17, only goes upto 200psi so won't do diesels. Also diesel ones need adapters to screw into the glow plug holes.

Last time I used it was on my daughters Fiat 500, got 75-140psi with engine runnng badly, 140-150 after head rebuild.
 

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Little Megger
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4,521 Posts
Discussion Starter · #3 ·
Thanks for that info... I can only unscrew 3 glowplugs as the 4th broke off the tip when I was trying to change it and the tip is still in there some 2 years later, just haven't got around to trying to extract it.
 

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Little Megger
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Discussion Starter · #4 ·
Just done a search , and looks like 400psi is expected on a new engine, so I'm looking for a gauge that reads at least upto 400psi.
 
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