i have a 89 civic hatch with a d16z6 i just swapped in, im having all the engine coolant slowly go into the overflow tank and once it starts to get low it overheats of course. i changed the radiator cap so thats not the problem. and also my car will idle up 500 rpms and drop back down repeatedly, but ive noticed when i turn my heater on full blast it will stop it from idling rough. also my oil isnt milky so theres no engine coolant in it and theres no oil in my radiator

im guessing it is my head gasket or head bolts, but any opinions or advice would help. thanks

 

i think you're probably right. certainly sounds like an issue with the headgasket. so your saying you swapped a z6 head onto your stock bottom end? or you dropped a complete motor in, and now its become apparent theres a head gasket issue? if you did a head swap did you tighten the bolts in the proper order, and to spec?

 

maybie thermostat id check that first its cheap then move on to the water pump its a circulation problem change the oil before you assume it to be head gasket failure head gaskets that fail will turn your oil pan into a overflow tank and the real overflow tank will always be empty also check that your rad fan turns on regularly

 

my thermostat and water pump are good, it only starts to over heat after like an hour cause the engine coolant goes into the overflow tank and fills it to the top. i just did a zc bottom end with a z6 head swap. yes i torqued it down to specs and in the right order, and i used a brand new metal head gasket. the head bolts are used though so i was thinking i might be getting a little lift on the head cause the bolts are used and arent torquing down right. its been doing this ever since i did the swap too. anymore advice would help alot. also i had to hot wire my radiator fan and it works.

 

For your idling problem its your FITV

 

idle air control valve

common problem with EFs.
getting a new one is going to be fun to find

 

iacv would couse idle issues, you said zc? wich zc dohc or sohc? they are close head to block wise close enough to jam one on but with bad results, bad idle can come from so many things, down to a bad thermo switch not the one for the fan, but the one in the head under the dizzy for the ecu. timing can be a problem one tooth off or dizzy being off, kinda need more info on why you changed your head in the first place.

 

i originally had a d16z6 in my car. but i threw a rod. so i reused the head and bought a zc sohc block to put the head on. my car only idles rough once its warmed up alot, and i can sometimes make it stop idling rough when i turn on the heater, i have a toggle switch for my fan that i hot wired. so my fan is on. and im not throwing any engine codes. any help? im lost im sitll guessing maybe head gasket or head bolts?

 

bump please!

 

If it is pushing coolant to the over flow bottle than it's the head gasket. they are not that hard to do on the single cam engines. you don't have to remove the cam to get to the head bolts. goto the parts store and get a head gasket set. i work at a dealership and seen this before, and it was the head gasket.