Well, here goes again. My rig is still using water, but maybe I'm a bit closer to solving the problem. Okay, I'm running a 4.6 liter, used to have a 4.2, and had no problems. I use about a quart of water per day....that's the problem. New development, I just put a water temp gauge in the radiator as suggested some time ago by someone here that described a way of slipping a manual sending unit into the upper radiator hose....Great trick!!!! worked easily, no leaks!!! Anyway, it turns out that my radiator temp at cruising on the highway is up to about 260?. If I am correct, water boils under 16# pressure at about 135?(learned that here too). Is the water evaporating? I am running a 195? thermostat, and the radiator never boils over, and the resoivor tank doesn't boil either, I just lose water. I had my radiator rodded and tanked too.I am not running a shroud, hard to find in Mexico, but I can have one made if necessary. Is my radiator temp normal?? I don't show any signs of water in the exhaust, so I don't think it's a head gasket. I have one other suspicion....It may a freeze plug on the rear of the motor. I had a helluva time getting new ones in when I put the new motor in, and had never done this operation before. I may have made one out-of-round. This would be my worst nightmare, having to pull the motor again to do exploratory surgery. Anybody got any suggestions, comments, theories? Thanks in advance......Rob

I run a 4.2 here in MN. I try to run it on the hot side, for more heat in winter but that leads to trouble in the summer months - without the shroud also. I have actually heard my radiator boiling, and need to add water every so often if running it heavily in the hot summer months. I am unsure if the water is actually boiling off, I just know it needs it and I've never had to flush it in fall when I test the coolant freezing temperature. It's always "coolant rich".

The only real advice I can give is for the frost plug. I had one that kept popping out, on my old motor, and I ended up adding another block heater in its place. They install with a V shaped retainer, reminding me of a wall hanger. Add a little slilly-cone and it's all sealed up. Good Luck down there! Too bad you don't really need a block heater...

Do you think you are burning it via a bad head gasket? Do you see any white smoke from the exhaust? If you used a shroud, the temp will drop a bit.

The boiling point of a 50//50 water/ethylene glycol mixture is 266 ?F. The boiling point further increases by 3 ?F/psig.

Plastic parts will melt at 266, so the car can never see this.

The thermostat is set to open and maintain a temp. of 195 ?F
The pressure rating of the radiator cap is 16 psig.
3 ? F/psig * 16psig = 48 ? F
so: 266 + 48 = 314 ?F This is the adjusted boiling point of water/antifreeze with 16 lbs. of pressure. The fluid should not boil if itÆs getting circulated, the concentration is correct, the thermostat is good, and if the radiator cap works.

135 at 16 pounds... you mean 135 C if it is 135 C then it should boil at about 275 F....

i wouldn't trust the gauge you put in, 260 doesn't sound right it should either be creating so much pressure that it boils over, or you are bleeding out pressure (and losing water...). a 195 should be wide open by 215 perhaps it has broke closed?? perhaps the radiator is defunct?? if you were in the states i would suggest finding a shop with an IR temp snesorand verify your results, but i dont know if you have acess to such toys.

Just in case anyone was wondering converting from C to F,Formula is multiply by 1.8 add 32 Great converting Sunder, Im a master plumber and agree with the bp formula,good luck <img src="/forums/images/graemlins/cheers.gif" alt="" />

sorry...i meant 235, not 135. i still think in Farenheit, not celcius....Some things will never change, and I'm still from Indiana, haha. <img src="/forums/images/graemlins/patriot.gif" alt="" />

okay, first, greasefingers...i don't think it is a headgasket, because i don't have any white smoke. i wish it were so, easy to diagnose and fix.

sunder, 275? okay, i read somewhere that 235 was boiling point under 16 lbs pressure. i'll take your esteemed word for it. and yes, you have hit it on the head, i am losing water, but there is no boiling sounds, actions. i just have to add water every day to the overflow tank. i am running straight water at this point because the coolant was getting expensive....and yes, i know it's bad for the water pump, etc. yes i know a mechanic with toys... what is this IR tester? is it infrared? is it a kind of dye that can be put into the water? thanks again in advance....Rob

Well now I gave you the formula of : the boiling point increases 3 ?F/psi and with a 16 psi radiator cap then 3 ?F/psi x 16psi = 48 ?F. So the adjusted boiling point of water under 16 psi = 212 + 48 = 260 ?F. This is exactly what your instrument panel gauge reads. Therefore you are boiling some of your water off. Your radiator cap must be constantly held in the open position, venting liquid and vapor into the overflow reservoir. You should see the overflow reservoir cap or the pressure disc, located next to the cap, leaking at times. If you had Anti-freeze in the system, it would be easier to trace.

An IR(infrared) tester is a gun lookin mawidge that when you point it at stuff it gives you the temp (ours is plus or minus 5 degrees F) basically you would point it your upper radiatot hose and it wouold tell you the temp.

unless your system is perfectly pressureized (not losing water/pressure) it will not boil at 260 anything above and usually the pressure overcomes the cap, lowering the pressure, and cause thing the whole thing to boil instantly. so... you are either running 16 pounds and are somehow still maintaining that with the leak(doubtful), or you are under 260 and your gauges are off and you o have a leak. have you tried the dye that you put in with the raditator, then run it for a week, then use a black light to spot the dye?? hae you just gone out and bought a new thermostat and cap?? for both it shouldn't cost more than 20 USD. im not sure where you would find the dye, but look around on the internet, maybe they ship to mexico.

Howdy JF2
The more I read about your problem the more convinced I am that you simply have a LEAK! Somewhere on that engine is a small trail of fluid! I think you should fill everything and park on a smooth dry place and run the thing in place for 30 or 40 minutes till you can see the fluid appear. I have never seen a head gasket leak that did not also leak compression back into the water jacket. You do not indicate that.
Your leak may be where you dread it the most.
Big Jim