hello everyone, I got a 1992 honda accord lx 2.2L with automatic transmission, 326 000 KM, I got a strange coolant leak, its like the coolant comes out of the radiator like by the cap or something, the cap I had on it was a 11 pounds but originally there was a 16 pounds so I put a 16 pounds back on it and it still do the same, I fill up the surge tank to max level and a few days after I open up the hood and theres some coolant on top of the fan and the tank is dropped to bottom level, its like the cap would release and Idk why, I made it run for half an hour without the cap and no bubbles or anything would happen...now im not the best mechanic lol I learned a few things but still if it was a head gasket there would be some bubbles or coolant would pop out of the radiator no? and also when the engine is hot, when I put it in park or neutral the rpm plays between 800 and 1500....now I heard it could be a vacuum leak but can this 2 problems work together??? thanks

 

Whatever is happening around your radiator cap, could be air is getting sucked into the system. That air can cause the idle surging.

So look at the radiator neck. There's 2 different "rings" where the cap gaskets seal against. Any scratches, gouges, or anything on those rings?

I'm pretty sure you want a cap with pressure 1.1 bar = 16 psi so you're good there. If it's not a Honda cap, does it at least have all 3 seals? One seal is self-contained (vacuum-break) and the other 2 seals go against the 2 rings in the radiator neck.

 

its a jobber cap, I will look at the radiator cap...ill keep you in touch thanks dude

 

Here's the long story so you can check the fit & operation...

The largest-diameter gasket under the cap seals against the top ring of the radiator-neck. That should always stay sealed so it doesn't leak OUT. That seal is above the tube going to the reservoir.

The next gasket seals against the lower/smaller ring down inside the neck. That one is held by the large spring and will lift if the pressure gets too high. In that case the coolant will get into the space below the largest gasket, and it will flow through the hose over to the reservoir.

The small disk in the center of the cap is a vacuum-break. It pulls down quite easily to allow the cap to suck coolant back into the radiator, from the reservoir.

If the hose leading to the reservoir has any holes, it won't suck back into the radiator like it should. Kinda like drinking through a straw with holes in it.