More Cooling Issues...Is My HG Gone?

[rico05]

No:coolant smell, massive overheating (more on this in a minute), boiling over, coolant in oil or vice versa.

BUT the car runs like crap cold, eats about 6-8oz of coolant a day (well, it "disappears"), with the car cold and rad cap off the coolant level will begin to rise in about 2 minutes and spillover radiator fill neck. I don't have a compression tester and I am too broke right now to get one (and I can't find one to borrow), so what do you think? God I hope its not the head gasket...
Modified by rico05 at 5:29 PM 10/9/2005

[rico05]

One more thing: the stock temp gauge seems to hold at about 1/2-2/3. BUT I just gave it some s*** on the way to my g/f's house to see if I could get any reaction. I drove down the highway w/o issue, but as soon as I turned down her street, did a hard 2-3 pull, the gauge JUMPED up to full "H", then setteled back down to about 4/5 up. I turned it off for about 10 minutes, and the gauge was back at 1/2 when I turned it back on. All hoses are in tact, there was no boiling over, no white smoke, nothing. I am really tired of losing coolant and my car running warmer than it should!

PS: My Autometer gauge on the upper rad hose USED to read 155-160, but lately it is reading 135. Those are temps in F. WTF??? As the temp at the stock gauge jumped, it went to 136 lol.

[slownslurious]

its reading that low because there isn't hot coolant flowing through the hose. that makes me think thermostat or water pump. Have you check those?

Mine has been leaking from somewhere on the back of the motor and it runs down the transmission and is dripping off near the driveshaft... if its a pinhole leak it only leaks at high rpms so it will leak while you drive and not while you are stationary so you'll never see the leak with it idling. Try revving the engine and checking for any water anywhere under the car.

[biosehnsucht]

rico05: have you tried re-bleeding the sytem?

slownslurious: look at the coolant return line from the turbo that runs along the back of the motor

[rico05]

Yeah, my return line was doing that till I fixed it a while back.

Bio, not really sure how to bleed a CA since there is no bleeder, but I have let it idle and watched the bubbles go. You know, it could be the thermostat. I know that when I overheated it once, it stuck it open (damn wax LOL). I think I may pull that apart later in the week when I have time.

I never thought about the pinhole idea. I will see what I can find revving it. I am only losing a tiny amount every day, and I drive quite a bit. Plus, it has been in the 90s until just yesterday LOL. Thanks guys. So more than likely my HG is good then? There is still stuff on piston engines that I know little about LOL. Like bad HG symptoms. Rotaries are so nice to work on!!

[float_6969]

Get a pressure tester. I don't think they're TOO much. They also have this dye that you can put in the coolant and you can use a blacklight and it will show right up.

[slownslurious]

yeah I wanted to get the dye kit till I found out that by the time you buy the dye and the light and everything its like $40... I'll check the return line its getting worse so I'm pretty sure its a rubber hose (has been leaking gradually more and more, as they usually do).

[biosehnsucht]

jack the car up, waaaay up in the front, and then you can just bleed from the radiator cap

I think we actually found the bleed screw at one point but I don't recall where it is, and it was practically impossible to use.. might have been that screw on the back of hte intake manifold where the turbo coolant return hits the back of it and then goes out another hose to rejoin the rest of the coolant..

[biosehnsucht]

My friend reminded me that the bleed screw (and it is a screw) is on the back of the intake manifold, where the turbo coolant return comes in and then goes down, its a horizontal screw..

also he's pretty sure that our coolant system is designed in such a way that you will re-develope air pockets if your resevoir is not kept relatively full..

[rico05]

Even with a Nismo rad cap?

[zero_gripS13]

hes talking about the resivor.. this is kinda true with any coolant system since when the colant gets hot it expands and bleeds off into the resivor but when it cools it sucks it back into the radiator.. and if theres not enough in there i think it can suck air into the radiator... so just make sure u have colant in ur resivor.

[slownslurious]

my radiator overflow bottle isn't hooked up, the barb broke off the radiator.

[float_6969]

my radiator overflow bottle isn't hooked up, the barb broke off the radiator.

THAT is very bad and could be causing you all sorts of problems.

Guys, please remember that this is a PRESSURIZED cooling system. What that means is that the cooling system is kept under a certain amount of pressure, determinded by the radiator cap if everything is working as it should. The purpose of this is to raise the boiling point of the cooling system.

The boiling point of water at sea-level is 212*F. When you add coolant this point generally is lowered. As you raise in altitude, the relative atmospheric pressure drops, decreasing the boiling point. This is one of the reason's to use a pressurized cooling system. A car running an un-pressurized cooling system that doesn't have cooling problems in Miami, may have cooling problems in Denver. If you keep the cooling system at a constant pressure, as determined by the strength of the spring in the radiator cap, then it doesn't matter where you drive, you know that the car will be fine if the rest of the cooling system is up to the task.

There are some factors that affect the effectiveness of this system. First of all is leaks. Any leak in a pressurized cooling system is now causing the system to be referenced to the atmospheric pressure, which makes it very easy to boil the coolant. When the coolant starts to boil, the coolant is no longer in contact with the internal block surfaces, but air is. Air is a good insulator, it's a poor conductor of heat. This is when metal parts start to warp and loose their shape. You will develop hot and cold spots on all of the cooling surfaces, causing the metal to expand at different rates, causing it to warp.

The overfill bottle is a VERY important part of this system. As the coolant heats up, it expands. This is where the change in pressure inside of the system comes from. If the coolant heated up, and didn't expand, we couldn't pressurize the system and increase the boiling point. But as the coolant heats up and expands, it will get to a point where the pressure in the cooling system is greater than the strength of the spring in the radiator cap. At this point the cap starts to open up enough to allow some of the coolant to flow out of the system. We could just drain this excess coolant out onto the ground or something as long as the cooling system never cooled back off again. Obviously this isn't the case. When the motor is turned off, the system begins to cool. As it does this, the coolant starts to contract. At some point, it will contract to a point where it starts to create a vacuum relative to the atmosphere. This is when air can enter the system. If you have any leaks anywhere, air will enter the system. If you don't have an over fill bottle, that little nipple on the radiator will draw air into the system. If your overfill bottle isn't full enough, it will draw air into the cooling system.

Air in the cooling system can act the same as the coolant boiling. It creates hot spots in the cooling system and can cause the metal parts to warp. A small amount is nothing to be concerned about, and won't cause any problems, and most systems, by nature, will work the air out via the overfill line into the overfill bottle where they're released.

I hope this helps everyone have a little better understanding of the system that their dealing with. If I missed anything, let me know...

[rico05]

Very informative post Ryan! Sticky perhaps? Anyway, looks like there is a reason for me to go ahead and purchase an in tact overflow bottle. A quick skim in the FSM shows that in fact, it says that the final step in filling/servicing the cooling system is to fill the overflow bottle HALF WAY. I have never done this, and it seems that we have found my problem! Thanks guys! I just assumed that with the Nismo rad cap that it would never even open, but it seems that is not the case. As always Ryan, you are a life saver!!! My engine loves you LOL.

[float_6969]

I feel so loved....

[biosehnsucht]

I am lucky that my overflow bottle / resevoir tank is broken near the top, not down where it would leak constantly.. the jbweld is mostly holding it together up there..

[slownslurious]

I tried to JB weld a barb onto my brass/copper radiator but it just came right off. And I don't have any money to take it to a radiator shop to have it brazed.*cries*