i have a d16z6 head on a ZC sohc block i swapped into my car and vtec only engages about 1/4 the time. My car runs a little rough and when its warmed up when its idling the rpms jump up and down by about 500 rpms but if i turn on my heater on full blast it stops the idling problem sometimes and also all my engine coolant slowly goes into my overflow tank when i am driving but my car doesnt get hot until im very low on engine coolant.

I've replaced my radiator cap and it never helped and my fan is hot wired so its always on when driving. Also i dont have any coolant in my oil or oil in my coolant and theres no smoke coming out of my exhaust. so im confused on what could be wrong! any advice would help alot! thank you

 

bump

 

Coolant filling up the resovoir is a symptom of a blown headgasket, have a carbon test done on your coolant.

 

bump

 

I am having a similar problem on my '01 Civic vtec. I did a compression test and all 4 cylinders hold nicely at between 158 and 162PSI. Could I still have a head gasket problem?

Steve

 

what obd generation are you running? the fast idle valve at the bottom of the older tbs have a valve covered by a plate wit 2 8mm screws alot of the time it can back out and needs to be turned back in (flathead should do the trick) you said when the coolant is low? is it leaking or being burned in the cylinders .....sounds like a blown hg really with the fluid filling the reservoir (hence cylinder pressure in the coolant system or low coolant levels) civic hg's are not forgiving at all after being overheated

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by FlatBlkEk &raquo;</TD></TR><TR><TD CLASS="quote">civic hg's are not forgiving at all after being overheated </TD></TR></TABLE>

Yeah, thats very true, usually once you overheat the engine and blow the headgasket its really only good for a boat anchor, occasionally you get lucky, not very often though.