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Discussion Starter #1
Last week I finally got the car all put back together. I replaced the passenger side motor mount. Installed the plenum. Replaced all cooling system hoses except for the heater ones which were done before. Cleaned and painted the radiator. Went for a test drive around the neighborhood and everything was fine. Temp was 175-185.

Yesterday, took the car to work. 1 hour drive there. No problems. Didn't leave for lunch. Left early at 2pm. Decided to take the interstate home to see how it drives at higher speeds with the new motor mount.

Was doing around 70 for a few miles and noticed the temp gauge was reading hot. Between the 175 and 250 mark. I turn the heat up to see if it would drop a bit. Nope. I then pulled off the side and drove on the shoulder a bit. Still hot. Decide to turn off the car.

Looked inside and nothing was obvious wrong. Looked under and saw a steady stream of fluid. Decided to call AAA since it was drizzling, cold and I had no tools or water.

Just now went outside to see where its leaking. Put water in. Started the car. Waited til the car got to temperature. No leaks. Water still visible in radiator.

What could have happened? How can I trouble shoot this more? Afraid of driving now in case it happens again.

Thermostat was replaced about a year ago. New hoses appear tight. No leaks before from the radiator.

Help!
 

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Discussion Starter #3
I followed the directions on the Iap site. I unscrewed the bolt on the water pump. And the plenum. Then filled until water came out of water pump. Put screw back on pump. Then filled til water filled radiator. Then screwed bolt back on plenum. I ran the car till it was warm. Put radiator cap back on. Filled overflow tank.

Is there something else?
 

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Discussion Starter #5 (Edited)
Just the fact that you are pondering makes me feel better.

I am going to drain some water and fill up with antifreeze. Drive only close by and bring tools and water.

How high can the temp get before I have to stop?
 

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But Mad North-Northwest
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Wait, were you running straight water? Or 50/50 water antifreeze? Straight water is not a good idea as it has a lower boiling point: should always be half and half.

If you were running straight water and maybe had a pressure leak in your cooling system, I could see it easily boiling over.
 

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Discussion Starter #7
No, it was 50/50. Just today I filled it with water to test for leaks.
 

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But Mad North-Northwest
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Okay, got it. Do you have a way to pressure test it?

An '87 has a radiator cap, correct? So the rental pressure testers you can get from most auto parts stores should fit it okay. I'd start with that.

My '91 has an expansion bottle and I had to buy an adapter, but IIRC the earlier cars just have a standard cap so that should work for you.
 

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Don't forget to re-torque the cylinder head after any overheating episode. An overheated aluminum cylinder head has a lot of exansion and will stress the head studs and cap nuts. Then when it cools down, it can lossen the cylinder head. It probably did not do so in your case, but re-torqueing an Alfa cylinder head is the easiest thing in the world to do and takes very little time. Certainly worth the effort to negate the risk of developing a head gasket leak as a result of any overheating episode.

Robert
 

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Discussion Starter #10
Do you have a way to pressure test it? So the rental pressure testers you can get from most auto parts stores should fit it okay.
Actually, just got one from Autozone! Will test in the morning.

Don't forget to re-torque the cylinder head after any overheating episode.
Good idea. Thanks for the suggestion. Will do that also tomorrow.

I used 3/4 of a gallon of water to fill it. So there is still some antifreeze in there. Got a coolant temp checker. There is enough coolant to go down to -10. It will be 27 degrees overnight. High should be in the low 50s tomorrow.

Still water all the way to the top of the radiator. The guy at Autozone is thinking a pressure related leak. Getting on the interstate got enough pressure to cause the issue. But it appears that letting the car sit and cool perhaps stopped the leak? That is why I still have coolant. Or the leak is high enough to leak out that much and stopped.

It was a steady stream when I looked yesterday. I didn't see any spraying.
 

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Where was the vicinity of the 'stream of fluid'?

Your Series 3 Spider has a coolant reservoir in the front, right corner of the engine bay. If you filled the radiator and the reservoir then, when the system got up to full operating temperature & the coolant expanded (normal operation) excess would be expelled. This would occur in the right front corner. But it wouldn't explain the higher temps.

Another possibility is if the small hose between the radiator (just under the cap) & the reservoir has a small leak. This can allow coolant to go to the reservoir (normal) but prevent it from being sucked back as the system cools down. After a few warm/cool cycles the reservoir would be overfilled and the next time it warmed up the expanding coolant would get expelled. And, in this scenario, the radiator ends up being underfilled which would explain the higher temps you experienced.
 

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Wait, were you running straight water? Or 50/50 water antifreeze? Straight water is not a good idea as it has a lower boiling point: should always be half and half.

If you were running straight water and maybe had a pressure leak in your cooling system, I could see it easily boiling over.
actually if a non AC car , 65% water and 35% antifreeze is a better cooling mixture...the 50/50 is for AC cars..
 

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Discussion Starter #14
Remember this was on the side of the interstate and it was drizzling. I just took a look and realized I was in no shape to fix it. I didn't spend a lot of time looking. I hoping it was a loose hose that I would find quickly when I got it home.

Where was the vicinity of the 'stream of fluid'?
I think mainly in the center under the radiator. The
small hose between the radiator (just under the cap) & the reservoir has a small leak
theory is something to also check. I think the expansion tank was still on the full mark.

Shouldn't it have sucked in coolant when it was getting low?

I will not have any answers until tomorrow.
 

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Shouldn't it have sucked in coolant when it was getting low?
I'm not following. It sounds like you filled it up to "full" before you drove off. When it got up to a higher temp, it would blow coolant out, not suck it in. Coolant expands when it's hot. If you stopped the car, the flow would stop and the coolant would continue to expand from the heat. If the overflow tank was already full, you'd get overflow out of the overflow tank. I can't be sure, but it sounds like that's what happened to you.
 

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Normal operation: cold engine, radiator full, reservoir about 1/2 full. Drive car, engine warms up, coolant volume expands - extra goes to reservoir. Stop driving, shut off engine. As it cools down coolant from reservoir is drawn back into the radiator. System remains full.

Faulty operation: cold engine, radiator full, reservoir 1/2 full. Drive car, engine warms up, coolant volume expands - extra goes to reservoir. Stop driving, shut off engine. As it cools down fault in reservoir system prevents coolant from being drawn back into the radiator. After a few warm/cool cycles the reservoir is over-full & the radiator is low on coolant. Next time the car is driven the low level of coolant in the radiator causes overheating & the excess coolant overflows from the reservoir.

Cooling system pressure is due to the temperature of the coolant. Temperature is controlled by the thermostat. Pressure is controlled by the radiator cap. The water pump has neglible effect on coolant pressure (driving slowly or fastly has no effect on coolant pressure).

Check the reservoir system for faults - usually a loose or split hose from radiator to reservoir. Hose must draw from the bottom of the reservoir. If no faults there test (or replace) the radiator cap.
 

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Discussion Starter #17
I just had to go out and look. The expansion tank fluid is only 1 inch below the full mark.

I didn't replace that hose. I just cut the ends off to get newish rubber. I didn't find any locally. I figured I would replace it later.

But if that theory was correct, the tank should be completely full, to the top. And it is not.
 

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Discussion Starter #19
Last week I filled it up to the max fill line. Didn't look at it yesterday at all.
 

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Sounds like you overfilled it (if it's like most cars, "max" is for when it's hot) then it expanded normally and overflowed your overfilled tank, then when it cooled down, it sucked the excess back in, leaving your level back a bit below the full line.
 
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