B16a overheating!

[The Bum]

Ok heres the background:

- JDM B16a2
- 1 piece thin head gasket
- Its in a 96 civic coupe
- Stock radiator
- The radiator cap is replaced


Why would it be overheating all the time? Its not excessive, but it barely overheats....

[dubcac]

Leak in the coolant system? How's your coolant level? Air in the coolant system?

Try flushing the system and refilling/rebleeding it.

[inspyral]

You're not losing any coolant, are you?

[The Bum]

no, the coolant isn't going away. What happens (forgot to mention this) is that when he pours in the coolant, most of it goes straight to the overflow. We dont think that there is so much in there that it would need to go to the overflow.

[inspyral]

So you're not *losing* any coolant, but it's getting displaced out of the ratiator and into the reservoir? Sounds like a blown or non-sealing headgasket to me.

[civicon19s]

Holy **** are you serious?? I am experiencing the exact same problems!! What the hell??? Is there anything else that could be causing this and if not, WHY would it be the head gasket? Thanks

[inspyral]

Originally posted by civicon19s
Holy **** are you serious?? I am experiencing the exact same problems!! What the hell??? Is there anything else that could be causing this and if not, WHY would it be the head gasket? Thanks

If the ehadgasket isn't sealing, compression from the cylinder(s) will leak into the cooling jacket. Since the cooling system is sealed, that extra pressure has nowhere to go, but past the radiator cap and into the reservoir. If that happens for a long enough time, it'll displace enough coolant to the point where your engine isn't sufficiently cooled, and it overheats.

[civicon19s]

Insyral, that is EXactly what happens... then the resevoir OVERFLOWS! Also, when i go to dump the resevoir, there is milky browish-black sludgy stuff at the bottom of the tank. Could this be oil leaking into the coolant?? help please! The car is about to go to Daytona and i need to be able to drive it back to Atlanta....

[inspyral]

That could be oil mixing with your coolant. Sometimes if you let the engine idle with the radiator cap off, you can see bubbles in the coolant, but not always. You could try a compression test, but when my headgasket was blown, my compression numbers were fine, and my reservoir only overflowed when i boosted.

[civicon19s]

yeah the car actually runs pretty well! Pulls just fine... ive just noticed coolant leaking in the car (floorboard) also.. could that be related to the pressure buildup maybe?

[inspyral]

Coolant leaking from your heater core wouldn't necessarilly increase the pressure of the cooling system, but it could contribute to the overheating you're experiencing.

[civicon19s]

otherway around.... could the excess pressure be CAUSING the leaking coolant in the car? How long and costly is it to change the head gasket? Im willing to do it myself...Also, why is the excess pressure NOT bleeding off from the system?? IE: i can not drive the car for 2 days and still has alot of built up pressure...?

[civicon19s]

One more thing... if there is a leak in the headgasket, you say the combustion pressure is forcing too much pressure in the system causing the coolant to overflow, correct? Well if this was the case, wouldnt the vacuum pressure on the intake stroke be sucking coolant into the combustion chamber causing white smoke and such?? Thanks man, appreciate the help!

[inspyral]

If your HVAC mix is set to cold, then there isn't going to be any coolant flowing thru the heater core. If it's note set to full-cold, and there's coolant flowing to your heater core, then the excess prssure theoretically might cause the leak you're seeing in the cabin.
Changing a headgasket is relatively simple, albeit time-comsuming. The total cost, if you do it yourself, would be the cost of the new gasket, the cost of new headbolts(unless you're running studs), and perhaps the cost of some copper spray. If you work quickly, you could have it done in a few hours, but if you've never done it before, it'll probably take longer.
When you shut the engine off, the hot coolant remains pressurized for a while, until it cools down. Once it cools, it contracts. Depending on whether or not the contracting of the coolant pulls coolant from the reservoir back into the radiator, what you're seeing after letting the car sit may be vacuum in the the system, and not pressure.
It is very possible for you not to see any smoke at all, and still have a blown headgasket. On the intake stroke, the intake valves are open, so the vacuum may not necessarily pull coolant into the combustion chamber as you theorized, since the open valves are a path of less resistance.
If I were you, I would do both a compression test and a leakdown test to see if they can shed any light on the situation.