Rad Overflow canister

[chico]

So for some reason my overflow canister is always empty. Rad stays full but the canister is empty. No apparent leaks and engine oil is good. I usually leave it empty and check the rad and it's full. Any ideas?

[djape1977]

if you're absolutely shure there are no leaks, yhan head gasket is gone

[chico]

Would I not notice that in the oil? Murky brown and foaming?

[majicwrench]

A tiny tiny leak could and can cause that. I would rather mine stayed full, but this is life. No worries, keep an eye on level. No reason not to continue to add coolant in overflow bottle too.
Keith

[So Cal Mark]

why would you leave it empty? It needs to be about half full

[djape1977]

there might be a very small leak somewhere, so the coolant evaporates before you notice it. check for white /greenish deposits on underside of where rubber hoses meet the metal parts. also, check cabin heater for leaks. if there are no leaks, than head gasket is gone.

there's several ways head gasket can go wrong:

1. there migh be a leak from coolant to oil system, manifesting itself in sludge resembling mayonaise that appears on oil filler cap and/or dipstick

2. there might be a leak from oil to cooling system. greasy looking coolant is the first sign.

3. there cam be a leak between combustion chamber and coolant. tell tale sign is bubbles in radiator.

4. last way to go is leak from cooling system to comnbustion space. water consumption and water vapor in exaust are first signs.

either of these failures is possible and first symptoms are hardly noticeable and get worse as time and miles go by.

in first case, it starts with just a hint of greyish sludge on the oil filler cap. many "experts" claim it's "just a condensation". of what? water in oil system? where did it come from? over time it will develop into sludge on a dipstick.

in second case, flush the system, refill with water and watch wath happens. if grease appears again on the surface it will end up with sludge in coolin system AND oil system.

in third case, problem will develop into coolant being forced out into overflow canister and out.

fourth case will progresively get worse with increasing coolant consumption, leading to misfire on one of cylinders, and if you persist, ending up with a cloud of vater vapour out of exaust and engine being unable to run anymore.

either of failures can over time combine itself with any or all of other symptoms.

[majicwrench]

This Expert will tell you that when fuel burns one of the by-products is water. Some of that ends up in the crankcase via blowby. When engine is used mostly short trips, never gets hot enough to burn off all the water. That is one place where water comes from in a crankcase. Another is simple humidity. Got in my Fiat this morn, it sat outside last night, everything wet (had to dry the seat) with condensation. Guess what?? Some of that would have formed in the crankcase too as it cooled down. Guess what?? The water can end up creating a chocolate milkshake look on interior surfaces of engine, esp those areas that cool down fastest, like dipstick tubes.
Keith the Expert.

[djape1977]

take that personally if you will, but each and every car i had that started showing sludge on the filler cap ended up with head gasket change.

i live in a climate where temperatures range from 110'f in the summer down to -15'f and my daily driver was made in 1979 and it dosn't show any signs of "condensation" although 90% of use is for very short trips.
two years ago it started showing sludge on oil cap during winter, and in the summer, 6months and 10k miles later it ended up with a cloud of white smoke (vapour) behind me on a highway. wanna guess what went south?

[chico]

So by doing the head gasket and exhaust gasket Am i then prolonging the life of the motor or is my head warped and it will need to be shaved down? Or at this point fill the reservoir and keep driving (has not been a problem yet)? The motor is 35 years old and I don't think she has ever been opened.

[djape1977]

try hard to find a leak and keep fillig the overflow canister too.
if you don't find a leak one of things i described will happen sooner or later and you'll know what to do.

fiat twincam heads rarely warp, from my experience. i've changed head gaskets on many fiats over the years and most of the times i don't even bother to check the head for flatness. just clean it from residue of old gasket and install a new one. only time i saw it warp was when one or several bolts were severely undertightened.

when removing a head, pay attention to ammount of torque you need to apply to loosen the bolts. if they were aproximately equaly tightened, no need to skim the head.

check the bolts visually for cracks or signs of stretching or twisting when you remove them. if they're original factory installed, in 90% of cases they'll be ok.

when installing new gasket, tighten according to specs, and re-tighten after about 700miles to a slightly higher torque.

don't ask me how much, i live in a metric part of the world and can't be bothered to re-calculate to lb/ft, i barely mastered miles and gallons . i tighten to 100 Nm, and re-tighten to 110 or 120Nm

[majicwrench]

Now I will agree with djape on a couple things, just keep adding water till something more definate happens. It certainly could have a HG issue, but it could also have lots of other things causing problems, leave gasket alone till it causes an issue, which it may never do.
AND don't ever just surface head because. If it is really warped, fine, surface it. Need a nice straight edge. Can't recall the last time I had a head surfaced.

Keith