Radiator overflow problem

[andyshoun]

I have an problem with my radiator loosing coolant when the engine is run hard.

The car is an 86 NA. I have all new hoses, a 3 year old rebuilt water pump and now a new reservoir and cap.

When I run the car hard; autocross or track days (hot or cool days) the car starts loosing coolant from the reservoir discharge hose (at the cap).

I've bled system. Either jacked the front of the car up or pulled it up onto a steep incline. I even made a tube and funnel for putting coolant in through the bleeder bolt hole.

The problem has happened since I bought the car 3 years ago. I replaced the reservoir and cap this summer and it still does it. I have no problems with normal driving.

What am I doing wrong? What should I check now?

[1itim]

Hi all, I would be interested in a solution to this as I have the same problem, and not just on 'hot' runs. my fans are working etc and have done thermostat and 'radiator' cap. (90kpa). is there meant to be a second plastic tank?

confused.
Tim

[mattdavis11]

If they are original radiators, I'd say they probably have out lasted their time. They may not leak, but they also may not flow, be it air through or water circulation within. You need both, and don't forget the condenser could be blocking the air too. Clean the exterior of them both to start with.

I'll grab a picture tomorrow and show you what I mean.

[Rasta Monsta]

Are you overfilling? Should be at MIN when dead cold. If you fill it to MAX, it will spit out coolant.

[kfanazini]

Possible head gasket


DIAGNOSING HEAD GASKET FAILURE
It's not always easy to tell when the head gasket it leaking. The symptoms are not always obvious, and can often mimic other (easier to fix) problems, such as blown oil seals, coolant leaks, vacuum leaks, etc. It often starts as a subtle problem, making it difficult to spot a bad head gasket at first. As the problem progresses, however, the symptoms can accumulate and leave little doubt. Careful attention to the car's symptoms, supplemented with testing as needed, can usually pinpoint a leaking head gasket. The most common symptoms and tests are:

Cooling System Problems. The head gasket forms the only barrier between the top of the cylinder and the water jackets surrounding the cylinders. When the head gasket leaks, combustion pressures escape into the water jackets. This creates air pockets in the cooling system and the same erratic cooling symptoms as a cooling system that needs to be vented (e.g., a rise in temperature at idle, with a very fast fall in temperature when you rev the motor). If you find yourself venting the system over and over, with no apparent coolant leaks, it may be an early sign of a bad head gasket. As the leak gets worse, the pressure in the cooling system may exceed the system's limit and push coolant out the overflow tube. This is usually noticed when the car is turned off. If the cooling system is fine when the car is driven gently, but overflows coolant and/or runs hot when driven hard, that's a tell-tale sign of a bad head gasket. Since many people don't watch their coolant level, overheating is often the first thing noticed when the gasket goes bad. Keep in mind that there are many reasons the car can overheat. Check out the cooling system thoroughly before pulling the head.

Originally Posted by andyshoun

I have an problem with my radiator loosing coolant when the engine is run hard.

The car is an 86 NA. I have all new hoses, a 3 year old rebuilt water pump and now a new reservoir and cap.

When I run the car hard; autocross or track days (hot or cool days) the car starts loosing coolant from the reservoir discharge hose (at the cap).

I've bled system. Either jacked the front of the car up or pulled it up onto a steep incline. I even made a tube and funnel for putting coolant in through the bleeder bolt hole.

The problem has happened since I bought the car 3 years ago. I replaced the reservoir and cap this summer and it still does it. I have no problems with normal driving.

What am I doing wrong? What should I check now?

[1itim]

Ok guys, dont know if mine was the same prob as andyshoun, but i thought the radiator cap may have failed as i had replaced it before. Rather than what i did last time, (buy the same as fitted) I actually checked a part list. It turns out the 1980 model NA wants a cap rated to 16 psi. I had a 13, fitted by the previous owner.

check your radiator cap. even if its right, perhaps it's spring has failed enough to vent coolant on your hot runs.

If this solved my prob, great, (I'll find out in the parking lot tonight) if i start blowing hoses i'll look at the head gasket...

Tim

[emoore924]

There are tools available with a tell-tail chemical pack that will detect exhaust gasses in the water system. This would indicate a failed head gasket between the combustion chamber and a coolant jacket pushing combustion gasses in to the cooling system and pressurizing it, thereby causing a coolant leak from the over pressure.

Not saying that's your problem. Try that cap first. Then if the problem persists, find a shop that has this tool and ask them to test your cooling system for exhaust...

[1itim]

in case anyone is interested, the 16psi cap has solved all the world's problems.
except for the brakes.
and the dampers.
or the bushes,
or the seats
or the....

[andyshoun]

Hey everyone, thanks for the responses. It sounds so obvious to me now, why didn't I think of that? I'll let you know how things work out.