Not sure if this is the right section sorry if not move if needed
So i've got a question bout my z6 i've searched and was just wondering what you guys thought. So anyways ive been building my z6 for quite some time now probably bout 2 years(vitara build), but i finally get it running and its running good for 2 days, then on the 3rd I go to start it for work and it sounds like it has no compression in a cylinder, but it does fire, it's just running rough. I get to work and do a compression test and cyl. 1 and 4 are 0 psi. 2 and 3 have 140psi (vitara pistons), I do a leakdown test and my intake valves on cyl. 1 are leaking like there stuck down alittle bit. and cyl. 4 intake and exhaust valves are leaking.

Now my question for you guys is do you think the valves and guides are just sticking form lack of lube and the heat cycles made them worse(I bought the head rebuilt two years ago, but it sat in just an engine bag, now is out of warrenty)? Or do you guys think it could be weak springs (from being held down just a little the whole time, i did have the lash adjusters all the way backed off but I never paid attention to see if there was still a little tension on some of the valves)FML. I just want to see if you guys think i could/should just pressureize the cylinders and swap in a full set of supertech springs or pull the head and have the whole head checked, i just dont want to buy another cometic headgasket, or pull the head again if i dont have to(this would be the third one/time) im just really losing hope on this build and have a **** load of money into it.

Oh and BTW while i have the two cyl. pressured up I can slightly tap on the rocker arms of cyl. 1 and 4 with a hammer and it seals back up, but once you turn it over same thing they get stuck down alittle bit.
Any helpful advise would be very appreciated, thanks in advance mike, BTW sorry bout the novel just wanted to make sure I had all the info someone would need. thanks again

 

sounds like your valve stems have loads of carbon on them if you are able to tap them and it seals

or your valve guides or seats have some sort of problem. i highly doubt anything is wrong with the springs

i would definetly pull the head and and inspect it...why buy a cometic headgasket??? i've had a vitara build for 3 1/2 years now and only use a Felpro MLS or equivelant (no EBAY gaskets though)

 

Well it dont have carbon im pretty sure, the head had new valve guides. I just hope they didnt mess something up cause its way out of warrenty (went to put it on and pulled head bolt threads so sat for a long time) but i figured pullin head is best way to go. And I have a few buddies that use cometic head gaskets on high boost set ups and have had really good things to say bout it

 

i work at a auto shop here in town and we had a customer that had a rebiuld head sitting in the cab of his truck for about a year and a half befor we put thehead on the motor for him we had are mechine shop look at it and thay found 3 valves and it turnned out that from sitting the vales had started to rust in the guids. thay said if we had just put the head on it would most likely seize a valve or two befor to long.

This maybe what happend to your head. when i have the head rebiuld for my 12:1 NA (P29 pistons from a d16a1) biuld i told them it may sit for a month or 2 befor i coould get it all together and thay put a little assembly lube on the valve stems for me to stop any rusting thay noted i my get a little smoke for the first 500 miles after the motor was installed but this way i wouldn't have to worry about then getting any rust in the giulds and hurting the head.

if your hed did bind a valve in the guid you will need new valves and guids for the efected valves.

it may also be that your valve keepers broke or that the tip(the stem end that the valve keepers lock onto) of the valve broke off
just did a motor swap on a 2003 saturn L300 that had 4 of 6 cylenders Pop the valve tips off at only 45,000 miles.

 

ya I have a feelin that I will be replaceing 6 valves and guides FML. It just dont make sense that only the
valves on cyl 1 and 4 would be sticking if that was the case you would think all of them would be sticking but maybe not thou. I dont know, I do know I really dont want to tear it down again but what can you do right. thanks for the advise any body else have any input?

 

Make sure you check valve lash before you do anything.

 

ya ive checked valve lash already there not too tight in fact when the valves stick they r way too loose but when they seat its all in spec. thanks thou

 

if the cam was in the head when it was sitting you may have had valves on no.1 and no.4 open alittle letting more of the valve stem get rusty.