Hi Folks.

I myself get tired of all those threads about this topic and recently searched alot. But I will once more consult the forummembers, because I think thats whats there for. Trying to keep my long story short...
Drive a 86FC NA. Last year during summer overheated once on a mountain trip. Afterwards constant water loss and bubbles in overflow -> blockweld + new thermostat -> no major problems maybe also because of autumn (colder weather).
About new year found out that waterpump was leaking a lot -> changed with used one -> no problems during winter
springtime water pump leaked again -> now new water pump + new 2 main hoses + the one near oil filter -> water loss -> radiator leaked again (did already some years ago and fixed with some welder) -> new radiator
So now pretty low coolant temperatures during summer (max. 1/3 at speeds > 100mph, 1/4 at normal cruising and even lower during idling)
BUT overflow bottle always stays full -> now changed radiator cap + hose from radiator to the bottle -> no difference
have no white smoke, and no water loss! If I let cool down the engine and open the radiator cap, a small amount of very little bubbles do float up, the same with running engine. But nothing obvious like guysher or hard starting...
So if I always empty the overflow bottle and take care of it I guess it will hold another year, but thats really annoing!

greetings,

Harry

 

...I'll be an optimist...

1. What kind of water/coolant mix are you running? Water has a lower boiling temp than antifreeze. This means that it will expand into a gassious state before antifreeze or an antifreeze-water mix. A gas takes up a lot more room than a liquid. This will push water out of the system.

2. What weight cap are you using? If you're running a stronger water mix, you'll need a stronger rad. cap. As I stated above, water has a lower boiling point, but it has to reach a certain pressure to expand. The transition between liquid and gas is rather sudden and violent...the lower the pressure the lower the temp this can happen at. A stronger cap will allow pressure to build a little longer before transforming.

...screw optimism...


3. You've dumped so many stop-leak type products into the engine that they're all trying to escape before the coolant...therefor keeping the coolant inside.

4. You're fubarbed.

5. sorry for this probably unhelpful, fatihue induced post.

 

Whats are you getting at I missed the question.

 

You wasted all the time and money just to stop the leaking when you could've done a rebuilt to fix it by now...


-Ted

 

So much pessimism around, lol...

Let's assume for a bit that the block weld didin't block all the little passages that you didn't want it to, and is creating its own havoc...Check the overflow line between the rad cap neck and the overflow bottle. Pull it if you wish, and take a good look at it for any small holes or cracks that would cause any vac created to be lost, resulting in all of the coolant staying in the overflow bottle instead of being drawn back into the rad after shutdown. Also check the overflow bottle & bottle cap for good sealing properties, and the neck/nipple under the rad cap for cracks.

 

Wayne - You'll have to forgive me for being a pesssimest here, but here's MY take on it

your overheating caused a minor distortion in a combustion o-ring. This is allowing a minute amount of exhaust gasses to push into the coolant system, causing it to pressurize and dump coolant. This will respond normally for a little more, as you notice your temperature slowly getting worse and worse.. Fair warning though, it won't be a linear growth. . it'll be exponential. . If it overheated by X degrees last time, it'll be at X*2 next time you drive it.

The easiest thing to do is to start saving up for a rebuild.. they're not that hard

and yes, Wayne, I AM bitter

 

Lol, you'll get over it. How's she running now?

 

She's running sweet I'm running without my thermostat (Until I get home!), and when I was coming to work this morning (~40 degrees out), my temp guage didn't get up to the "C" line.. . the good: My car is DEFINATELY not overheating. The bad: I was not heating up at in the cockpit area..

edit: I think my idle problem is due to my electrical system, either my alternator doesn't put out at idle (but puts out about 13.5ish running), or my battery is dead/dying.. or both.. I haven't had time to deal with it, as it's fine as soon As I push the pedal, so i'm going to just change my throttle cable tension to deal with it for now. Not exactly "mazda" approved, I know, but it'll work

 

Still got the BAC valve? See how she idles warm with the initial set coupler jumpered- that'll give you a clue as to whether it's an electrical or mechanical problem...

Lol, yeah, on a cold night like that down here, mine barely gets above "C", and that's with the thermostat in. She heats up the cabin well, though...

Glad to hear she's finally running well