Failed Compression Test

[L0Ki]

Hey Guys,

Just tried to do a compression test on my RB20 and have given up becuase i think the guage or tester is faulty.

I bought one of the crazysales ones of ebay (its the cheapest) and i must have turned the engine over for the quivelent of about 30 secs (not all in one crank) and the guage was only reading 70psi. I was starting to fell bad for the starter motor so moved on to the next cylinder to make sure the first just didnt have only 70psi but i did the same thing and only got 60psi before i gave up.

Surely i shouldnt have to turn the engine over for so long to get a reading? A few cycles of the piston should give a good result?

The engine was hot, throttle fully open but no oil dropped in the cylinders.

Cliffs: So is there something wrong with my technique or just a faulty guage?

P.S: someone wanna lend me a known working gauge?

[boostn0199]

Yeah I bought one from crazy sales there faulty mine didnt register at all the fitting leaks to the gauge I think.

[blind_elk]

You should be able to get a compression reading in about 5 cycles of the engine. The first cycle will generally give most of the compression reading. If the gauge doesn't behave like that, toss it and get a decent gauge - they're not really that expensive.

[Guilt-Toy]

as long as they are all showing 15% within each other then you are good.

if you really want a acurate reading borrow a decent gauge.

[GTR_JOEY]

You want them to all be within 5%

Though I'd say 60 and 70 psi is too low

I know for a rb26 Nissan recommends a rebuild at 125psi

I'd be getting a second tester and doing it again and then checking factory specs