Compression problem

[madsav]

vn series2 v6, had a blown head gasket this is how it was before i did the head gasket
1stcyl-150psi
3rd-150psi
5th-150psi
-----------------------
2nd-45psi
4th-0psi
6th-150psi
--------------------------------------------------------
After
1stcyl-150psi
3rd-150psi
5th-150psi
-----------------------
2nd-150psi
4th-60psi
6th-150psi

Car does have rough ideal , Anyone got any ideas on what i can do next to fix replace etc

[strgas]

may have burnt valve in number 4 , is it choofing out the exhaust pipe or the inlet ?

[madsav]

sounds liek the exhaust, also noticed when i removed the spark plug it was not yet and didnt smell of fuel but the other did

[strgas]

carry out a cylinder leak down test and listen for air escaping thru the exhaust and intake , either way the head over number 4 pot will have to be removed and have the valves checked , did you have the heads shaved when doing the head gasket/s , pressure test the heads for cracks too

[madsav]

nope tryed to rush the job guess that might have come back to bite me in the arse . how do i do a cylinder leak down test ?

[strgas]

leak down testing is used to check for loss from a cylinder via the rings but is also good for checking valves . remove the rocker gear allowing the valves to seat fully and apply compressed air to the given cylinder listen for air escaping thru exhaust pipe or intake also check for bubbles in the cooling system .

[VNracer34G]

leak down testing is used to check for loss from a cylinder via the rings but is also good for checking valves . remove the rocker gear allowing the valves to seat fully and apply compressed air to the given cylinder listen for air escaping thru exhaust pipe or intake also check for bubbles in the cooling system .

No need to remove rocker gear - just turn it till its firing the cylinder your checking - also listen for air escaping from the oil filler or dipstick tube which tells you its rings

[strgas]

when the cylinder is in the firing position the piston is in TDC applying air to the cylinder can cause the piston to move downs and rotate the engine moving the cam and opening the valves you which to check , there will always be a small amount of by blowby from the rings as they dont seal 100% , thats why a leak down test testes for percentage loss from each cylinder.

[madsav]

cheers guys will seek into it tomorrow at work and see how it turns out thanks

[madsav]

Well i checked the cyl and it held pressure ,so the piston/rings and bore is good, im wondering if maybe 1 of the valuves for the cyl might be bent or sumthing? or would my best bet now be the head is warped?

[wortus]

A bent valve would probably stick open or not move and break the rocker gear I'd think ? If it's holding pressure then the rings and valves should be OK?

[madsav]

might grab another head from the wreckers get it cleaned etc and see how that goes