I've started having an overheating problem recently. I've replaced the radiator, cap, thermostat, hoses, flushed the heater core and water pump. If i drive at mid to higher rpm (3k+) it builds a lot of air pressure in the system. The hoses get really stiff and when i take the rad cap off, you can hear the air escape and the reserve tank bubbles like crazy.

I recently changed the HG, but I'm looking at doing a leakdown test here this week to see if I screwed it up putting the head back on. I've also been told it could be the exhaust valves letting gas past the seats and that could be causing it to overheat.

Other then the stuff I listed here, what else is there?

 

The valve seals is a new one on me. They would leak into the oil breather system and you would build up crankcase pressure, which would cause you push oil. Or if you were leaking past the seats that would just lower you compression.

Have you re-torqued the head bolts. I would re-torque them a number of times after a few heat soaks until the bolts or nuts stopped moving.

Did you have the head checked for flatness before you re-installed it?

Have you been to d-series.org and turbod16.com

 

I was actually thinking about doing that this week too. I had that idea a couple days ago, but I kept forgetting about it.

I took the head to a machine shop and the guy said it didn't need planed.

Any other ideas on top of those?

 

Do you have the correct radiator cap ?

Is the timing correct?

Is it boosted?

 

You need to bleed the cooling system, it is supposed to build up pressure in it though.

 

^ I assume, with all the stuff he's replaced he knows that. But it never hurts to ask.

 

Well some people do not understand that your cooling system is SUPPOSED to be under pressure.

 

yes the cap is correct, the timing is dead on, and yes it's boosted.

i've flushed the entire system, put new coolant in and bled it 3 times, a half hour each time. i know it's supposed to be under pressure, but both radiator hoses get stiff as hell. also, i leave the reserve tank empty and after driving it for maybe an hour, it'll be half filled and it doesn't get sucked back into the system when it cools down.

 

Boosted, that makes this easy, go buy HG, your's is toast.

 

i just changed that though. like 3.5 weeks ago.

 

When are race engine had sinking sleeves, it would continue to do the same thing. I did 5 HG's in one summer 2006 so we could keep racing.

 

but i haven't gone into boost since i've done it. when i did it, i found out my valves were in really bad shape, so i haven't taken it over 3k since then.

 

also, i can't find your posts on turbod16.com about re-torquing the head bolts. (1992Si)

 

im having the same problem you are lol, and mines not turbo'd its stock besides an CAI and ebay exhaust i replaced my thermostat that didnt work so i just took mine out. now i can drive all day long and it wont overheat until i hit a hill, if im on a hill for more then 2 minutes the temp gauge goes right up by the H redmark, at that point i turn my heat on and it shoot way the hell back down. I'm thinking my water pump. i dont know. the engine is getting rebuilt for turbo next month and there putting a new water pump & timing belt on so im just going to wait until then before i mess with it, for now it gets me back and forth to work.( sucks i have to take the long way to skip the hills though lol

 

You need a thermostat. Without it the car won't warm up enough which will cause it to burn a lot of gas, the idle will be high, the engine won't be efficient enough and so on. You need that thermostat in there.

Is your radiator fan working?

 

for mine, it ended up being the head gasket again. xfx, if you check the radiator hoses when it overheats, they'll probably be hard as a rock from the pressure build up. it's probably your head gasket too, unless you haven't bled the system or are getting air in it some other way.