4 and 5 cilinder 0BAR

[spions]

I put my ABY engine in coupe quattro.
Started and found out that 4 and 5 cilinder have 0BAR pressure.
I today changed head gasket and same 0BAR in last 2 cilinder.


Your verdict and ideas!!!!!!!!!

[UrS4boy]

Did you look at the valves in those cylinders when you had the head off? They might be a) stuck open or b) burnt on their edges and not sealing properly.

[spions]

They moving properly.But i don't know if they sealing.

[jonnaz]

valves or piston rings are not sealing most probably the valves.

[UrS4boy]

They moving properly.But i don't know if they sealing.

If the engine has been sitting somewhere, open to moist air, the valves might have rusted and become "furry", preventing a good seal (BTDT). That can only be checked with the head off again.

In the meantime, since you might have a ring issue on cylinders 4 and 5, dribble some oil through those two spark plug holes and see if that gets you any compression. It that works I am afraid that you will likely need to replace the rings (and then you might as well do all five cylinders and redo the head while you are at it). Sorry.

[spions]

ok.
So can someone offer ABY head in good condition?

[jonnaz]

did you put the new head gasket on? if so do the check above for the piston rings. if the rings are good then you can take the head off check the valves. if there not sealing check there not bent, i dont think they will be. the valvs can be reground so they sit correctly and seal. save buying a new head.

[spions]

Engine was standin one year outside so it can be valves.
Yes I put new head gasket.

[jonnaz]

i would take the head back off after doing the test for the rings and check the valves are sealing. also check the condition of the cylinders while is off.

[spions]

they seems to be fine.Cylinders.
How to check if valves are sealing?

[jonnaz]

if it is a valve it will most probabaly be an exhaust valve. the valves can be checked by lying the head on its side and pouring water down the port on the cylinder head with the valves in question closed if there not sealed the water will leak out.

a better way is to use air pressure but you will need a bung that will seal in the port on the head.

someone else might have a better way of doing it.

[mcandmar]

Even with badly sealing valves/rings i would expect to see some pressure. 0 bar is very odd indeed, that would need to be a very large air leak somewhere

[spions]

that's why i don't think it is piston rings.If so then it would be full with oil.....
In first 3 cylinder are 11BAR pressure

[newsh]

Have you checked valve clearances?

[rs200]

if you realy want to find out where is problem, take cilinder head out of ongine... take cams out.. than all valves are closed. turn head around and put a fuel on valves , if the fuel will fooling down , you will see where you have leak, you will strictly see which valve have a leak...

do the same thing with pistons, put fuel in cilinder when the piston are on bottom end, if will loosing the fuel the rings are bad...

I do this test lots of times... simply but efective test.. good luck.