Hi all.

 

My brother has just had a replacment engne fitted in his skyline (rb20det) a compression test was carried out when engine was fitted and all was ok, but problems have started to arise since it's been run , so another compression test was done and no5 cyl is reading 0 the rest i think are relativly within tolerance,,,, my question is what would cause no compression in no5 when all the rest are pretty ok........ thanks Jay

 

ps. i can get more detailed info if its required. cheers

You need to get a cylinder leakage test done instead - this will pin point the area of the compression leakage...

Ok ill let my brother know thanks....top man

Cylinder leakage test is done with the test cylinder at TDC with both valves closed, ie full compression, but the spark plug is removed and a compressor is inserted in the plug hole. You then listen to the intake port, the exhaust port, dipstick and watch for bubbles in the coolant. Any hissing sound from the ports/dipstick or bubbles in the coolant will tell you where the leak is. Hissing in the intake=intake valves. Same for Exhaust. Hissing from dipstick is rings/piston damage (although with 0psi compression it will be holed piston if from here). Bubbles in coolant means blown HG (doubt you'd get 0psi compression with a blown HG though)

And hissing from exhaust means that your valves are not seated correctly or stuck.

Snoopy... your brothers the one on ebay in Plym?

Snoopy... your brothers the one on ebay in Plym?

 

 

No M8 must be sombody elses.......

Cylinder leakage test is done with the test cylinder at TDC with both valves closed, ie full compression, but the spark plug is removed and a compressor is inserted in the plug hole. You then listen to the intake port, the exhaust port, dipstick and watch for bubbles in the coolant. Any hissing sound from the ports/dipstick or bubbles in the coolant will tell you where the leak is. Hissing in the intake=intake valves. Same for Exhaust. Hissing from dipstick is rings/piston damage (although with 0psi compression it will be holed piston if from here). Bubbles in coolant means blown HG (doubt you'd get 0psi compression with a blown HG though)

 

 

Thanks I have forwarded this onto my bro now, he is gonna have a chat with his mechanic......cheers

And hissing from exhaust means that your valves are not seated correctly or stuck.

 

Their is a hissing noise comming from the rear of my exhausts behind the petrol tank around by the diff, what valves could be stuck? could this be the cause of my exhaust smoking now and again?

Thats the fuel pump you can hear lol

Thats the fuel pump you can hear lol

 

You can tell I obviously no nothing about these cars yet, I am learning though thanks to this club.