overheating GTV

[poohbah]

That would be totally sensible Paul. At moment just trying to limit expenses, having just bought the GTA and spent a couple of grand to get it roadworthy.

[Beatle]

I can't remember how accessible a 116 radiator is, but when the engine is warm place your hand on the core to check it's relatively consistently warm across the surface.  If there is a cool section, it's likely the rad is partially blocked.

And the pepper idea is to fix a pinhole leak (rad/casting/headgasket).  I don't know how it would remedy overheating from other faults?

[poohbah]

cheers Beatle, yep you're right about the pepper. There are no indications of a leak in either the rad or any hoses (or it wouldn't have come out of the overflow).

I appreciate everyone's input. When I get a chance over weekend (hopefully) I'll check the upper/lower hoses as it initially warms up to normal temp as suggested, and then try to get the thermostat housing off. It does seem like that is a likely culprit.

If that's not it, I'll move onto the radiator.

I've got three weeks off over Xmas coming up, so I should have time to have a proper fiddle about. In between selling the 156 and hooning around in the GTA...

[bazzbazz]

I've got three weeks off over Xmas coming up, so I should have time to have a proper fiddle about. In between selling the 156 and hooning around in the GTA...

Don't forget the fire extinguisher . . . . . 

[poohbah]

all good bazz - three Alfas. three extinguishers.

[MD]

Given the age of the vehicle, the radiator has brass tanks and is entirely serviceable. You should do this irrespective of what ever other faults the cooling system may have. This gets you to a base level to start any other diagnosis. Without being certain of the cooling abilities of your radiator, chasing other faults will never give you certainty.

From there a list of faulty contributors:-

1 Faulty/inoperative thermo switch.
2 Faulty thermo fan
3 Poor power supply to thermo fan (Voltage drop, low current supply)
4 Faulty thermostat
5 Overflow pressure cap has poor location, has old hard rubber, not holding pressure. System running at atmospheric pressure.Replace cap with original. If using aftermarket, it needs a 14 PSI cap with the correct reach and seal radius. Do not overlook this.

[poohbah]

Cheers MD,

Good points. Just to confirm, the fan comes on a the correct temp and runs full speed, so fan switch appears to be fine. I also replaced the cap on the overflow tank with a recommended one a little while ago as the old one did appear to lack sufficient tension in the spring. It hasn't boiled over since, but is still running hotter than normal.

[Colin Edwards]

Time to rip out the radiator and take it to the most experienced specialist radiator mob you can find.
Hand the radiator to one of their "experts".  If this mob is any good they will be able to tell within seconds if the radiator is suspect - just by the feel of it in their hands.
All things being equal, a partially clogged radiator will be heavier than an unclogged radiator.  A very experienced radiator "expert" will know straight away what your radiator should feel like.  If it can be re-cored they will recommend it - and probably suggest an increase in capacity / surface area while the header tanks are off. 

[MD]

You know the saying "All roads lead to Rome?" Well, substitute the word radiator for the word Rome.

If you elect to re-core the radiator, nominate no more than 12 fins per inch. Major red light overheat warnings on the 75 series is due to too many fins per inch (over20) and the fans cannot pull enough air through during idle time at traffic lights in hot climates like Qld. Usually not a problem on the move but in stopped or slow moving traffic, yes worrying the shit out of 75 owners.

Also you could be running a lean mixture unknowingly. Have you checked the condition of the carburetor coupling rubbers for fractures top and bottom?

I haven't read the entire post but will just add that water pumps do get disintegration of the impellers so all that is moving is the shaft with very little circulation.

[Craig_m67]

Ya just need a need a chocky moove poohbah

(Or inspiration via YouTube from the original TV commercial)
https://youtu.be/gVMqa26xRDs

[poohbah]

Great yarn sportiva. About ten years ago, I remember making multiple treks from the side of the road to a water trap at a local golf course to fill up a dumped 600ml coke bottle when the top hose on my first 156 split near the clamp. I sawed off the split end and reclamped it so I could get home.

I do plan to get the thermostat off once I'm on leave next week. I'll provide an update when I have news to report.

So I don't have to find a choc milk carton - what sort of gasket will I need? Does it usually come with the replacement thermo or do I need to buy it separately? And should I also use some kind of sealant as well? I reckon there is sealant of some type on the current thermo housing, which is probably why I couldn't get it off last time.

[poohbah]

ok thanks

[GTVeloce]

Sportiva's yarn reminded me of a dodge fix we did on a Nullabor crossing in an early 80's Saab. The upper radiator hose developed a split and was leaking. Not much chance getting a suitable hose on the Nullabor so we cut a piece of cardboard from a Colgate toothpaste packet and used a hose clamp to hold it on. A year later we still hadn't changed it...

It's been a while since I messed with a nord thermostat but from memory it is fairly easy to pull out, seal and drive away so I would go that way first before pulling radiator out.

[carlo rossi]

do we have the answer it wasnt the cap was it?
but i change that regularly ,i have seen them rust off

[poohbah]

Haven't got to it yet, Carlo. Doubt it was the cap as I changed it. It hasn't boiled over again, but I haven't really driven it far enough to know, though it still seemed to run hotter than normal.  I have bought a new thermostat, gaskets and sealant so i Intend to get the old one off this week.