Foam in radiator

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I've heard that if you see bubbles come out of your reservoir then this could mean a bad HG. Is this always the case or just a possible sign? I did a coolant drain refill today and when I was refilling I noticed a foam come up to the top during the beginning of the refill and engine running. Mind you I didn't see this coming out the pipe in the reservoir but the radiator cap hole. Should I start getting parts?
 

e9999

Gotta get outta here...
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if you have just refilled, there will be plenty of air in the system. It takes a while to come out. So, no panic yet!

Either way, there could be bubbles, but should not be foam IIANM. Did you use a coolant system cleaner with surfactants?
 
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I started this thread after the first drain and refill. I came home in another car to get some things and let the truck cool off again. The foam returned after the second drain and refill. While it was coming to the top I kept pouring water in as to overflow the radiator and make the foam go out. I thought might as well since I have all this distilled water on hand. Whether it helped anything or not I don't know but the third drain and refill I didn't see any foam.
 
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I personally wouldn't worry until you have the system completely filled and all the air is out of it. You will need to drive it a few times and refill as needed. Once it is back to normal I would be concerned if you still have foam/bubbles.
 
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if you have just refilled, there will be plenty of air in the system. It takes a while to come out. So, no panic yet!

Either way, there could be bubbles, but should not be foam IIANM. Did you use a coolant system cleaner with surfactants?

Can you please elaborate? What is "a while"? 1 hour, 10 hours, or 100 hours of engine running time?
 
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Can you please elaborate? What is "a while"? 1 hour, 10 hours, or 100 hours of engine running time?

I'd put some hours on it. The last time I did my coolant, (6 months ago), I drove it around town about 3 times for 20 minutes each time or so and the refill bottle didn't go down. Then about 2 weeks later it needed a pint or so. I'll guess that was 40-50 miles or so. It's been full ever since...
 
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i would say the period of time would be when you stop having to add to the res. then the air should be out of the system
 
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It took 20 minutes or longer of idling for the engine to get hot where I could barely hold my hand on it. I kept feeling the engine cause the thermostat never seemed to open up with the rear heater and front heater blowing. After 20 minutes I just got in and drove down the road about 1/4 mile. That's when the heater got hot. I got out and put a little water in but not much. I could still open the radiator cap since it hadn't fully pressurized. Does this sound unusual?
 
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i don't think any of this sounds unusual.

I kn ow when my roommate flushed his coolant he had some trapped air in his system that he just could not get out. It eventually passed, but took a while (along the lines of weeks).
 
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I had air bubbles too but this foam was more frothy than just regular air bubbles. It must have been something in the old coolant that made this happen since the third drain and refill I didn't see any.:meh:
 
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I've heard that if you see bubbles come out of your reservoir then this could mean a bad HG. Is this always the case or just a possible sign? I did a coolant drain refill today and when I was refilling I noticed a foam come up to the top during the beginning of the refill and engine running. Mind you I didn't see this coming out the pipe in the reservoir but the radiator cap hole. Should I start getting parts?
Problem could be leaking transmission cooler inside radiator. This causes white foam. Or if someone put windshield washer fluid in antifreeze reservoir this would cause white foam. Solution: flush antifreeze twice then fill with new antifreeze.
 
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Problem could be leaking transmission cooler inside radiator. This causes white foam. Or if someone put windshield washer fluid in antifreeze reservoir this would cause white foam. Solution: flush antifreeze twice then fill with new antifreeze.
You can do a chemical test of antifreeze for hydrocarbon traces. This will indicate a blown head gasket. Never, never, never use any form of stop leak !!!!!!!!!
 

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