[zookster666]

I was working on my g16a this morning and when i turn it over by hand i can here a hissing sound around the crankshaft area with the sump off. It sounds like the compression is coming past the pistons. Does this mean my engine needs new rings or is this normal?

[steak_knife]

You will get compression leakage past the rings, piston rings don`t & can`t seal 100% by way of design, oil has to be able to get to compression rings or thay will seize, if an eng isn`t using a little bit of oil there`s something wrong with it. I would`t to concerned about it . This is why we have PCV, positive crankcase ventilation.

Steve.

[zookster666]

It just seems like alot of it or all of it when i crank it and stop number 2 piston at the top it lets all the compressed air past the piston by the sounds of it. I dont want to waste any more money on it if its goin to use oil and need replacing in the near future.

And should it all bypass the piston if it not running (turning it over by hand)

[steak_knife]

It has to go somewhere, with out hearing it i can`t say to bin it or not , all motors hiss at ya when turned over.
Did you have the pistons out??? if you did, did u put the comp rings gap 90 to 180deg apart??

[zookster666]

i didnt have the block apart im just replacing all the deals and gaskets i will get a video and post it up
the noise is at the end of the video and its blank as the lens cap was on

cheers

[steak_knife]

I`m over on downloads, so i could be at your place before that works.
If it`s only in no2 you`ve got a prob, i could come have a look at that & that g/box if ya want.

[zookster666]

where abouts in brissie are you?

[steak_knife]

base of Mt Coother

[zookster666]

Do you realise its about a 45 minute drive to my place?
Your quite welcome to come have a look but its not urgent i got the engine and gasket kit free so its not a loss untill i spend money on it if you know what i mean.

[steak_knife]

45min`s round the corner, if you still have that box next weekend i`ll come & grab it.
Be in touch during the week.
Cheers, Steve.

[Hybrid]

Isn't part of the design of pistons and rings that the combustion pressure forces the rings against the bore giving the seal. If you are just turning it over by hand you'd be getting nowhere near combustion pressure therefore not getting as good a seal as when the motor is actually operating. I'm by no way certain of this but it's just a thought on why it may appear to be letting a lot past.

[zookster666]

i thought this at the time but im not sure as i siad i dont want to waste any money on it if its no good

[31zook]

What compression in PSI should i be reaching? Mine start at 142 through to 157psi.

Is this alright?

[jdk81]

31zook wrote:

What compression in PSI should i be reaching? Mine start at 142 through to 157psi.

Is this alright?

Is it g16a 8v or 16v?

Based on g13ba, assuming 8v and same comp ratio, so I believe same specs will apply

199 psi is standard
170 psi is the limit
Max difference is 14.2

What are the readings when wet?

If its 16v its, way below.

[jdk81]

From baleno FSM for g13 and g16

199 psi is standard
156 psi is the limit
14.2 psi is the max difference

It appears yours is shithouse
If it doesnt improve much when wet, pull the head and lap the valves.

Lapping compound and a head gasket set is just over $100.

I used a cordless drill to lap mine quickly.
Then install new valve stem seals (in the kit).

If it increases when wet, time to get the whole lot done and remember, aftermarket engine never seems to last as long as the factory work.

[Rhinoman]

How are you measuring the compression? the engine should be at normal operating temperature, the plugs out, the battery fully charged and the throttle wide open. Compression low but relatively even can be a sign of bad valve timing.