I have a d16z6 and I have some annoying problems maybe you guys can help me with. First off when I give it throttle there is a bunch of pressure in my radiator. It idle surges when its cold until it warms up OR if I put a business card in the middle of my IACV it stops.

Next thing is when I disconnect my IACV remove the card also, and try to turn the idle up it won't go past 500 no matter what I do. It will if I advance my timing but it starts to knock if I do that so I dont want to do that. I might have found a small vacuum leak on my intake manifold or the hose that runs directly under the IM, now would either of these cause the pressure in my radiator? Theres no smoke or any symptoms of a head gasket, i've even used head gasket sealer.

I have replaced the IACV multiple times and cleaned them also, I tried raising the idle using the steps in the manual and just nothing works. Any help would be great, thank you.

 

Why don't you think this^ is a sign of a blown head gasket?

 

Because theres no other signs of a bad head gasket. I suppose I should do a compression test but still it runs fine it just seems like I have a vacuum leak. Im going to replace my intake manifold gasket tomorrow and ill see if that fixes anything. Pressure pushing out from my radiator when i give it throttle can't only be from a head gasket. I blocked off the IACV vacuum and im pretty sure it didnt push as much if any with the radiator cap off. Im pretty stumped though.

 

How many signs of a bad head gasket do you need?

 

I just dont think that is the problem. Ill change the manifold gasket tomorrow. Ill let you know how that turns out.

 

Pressure in the cooling system like that is pretty much guaranteed blown headgasket. You will almost never see the oil and coolant mix in a Honda, so don't expect any milkshake. It's also not that uncommon for there to be no white smoke either.

 

I've had a real subtle blown headgasket in my 93 del sol D16z6.
Just a few air bubbles in the coolant overflow and a hard upper radiator hose = a blown headgasket! Don't drive it like this! You can do further damage like warping the head ( if it's not done already) or cooking pistons and searing bearings. Don't be in denial. Catch it early and check the block and head for cracks. You might get by with just a headgasket and mill the head. Start looking for a good replacement running engine just in case you don't want to pay for a total rebuild.

 

There are NO SET SIGNS of a blown headgasket. So 2+2 does not equal 4 in this case. YOu can pressure test the system and get it out of the way but you CANNOT simply dismiss it because the symptoms don't match your criteria.

Your headgasket is blown. Unless you're boosted then you're probably getting headlift.

 

Well I couldnt get to the bolt behind the IM and one on the left side was starting to get stripped so I didn't replace the gasket.

 

Update: So I got it checked out they said it wasn't the head gasket and my timing was right on. Now when I unplug my IACV nothing happens (besides CEL), but when I plug it back it sounds like its perfect for a second and then goes back to idling really low. Bad IACV?