Coolant fill level

[dab67]

This may be a real ignorant question. What is the proper level to fill a radiator with a 350? I seem to be having to put coolant and water in the radiator every two or three weeks. Today I filled it again to just about and inch below the top and warmed in up and after shutting in down it ran out the overflow hose again. Could I need to have my radiator checked and recored? Or should I put in a larger radiator? I believe my is the standard two core. Nothing special about the engien when I rebuilt it still a pretty stock 350 bored +30 and a little above normal cam. Would a 3 or 4 core be suited better for a 350 powr glide tranny?
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Thanks CRG!

dab67

[Steve68]

Look on the inside (engine side) below the cap for a line with "fill line".  It should be somewhere about 3" down.  Start with a coolant level there.  If you are not having any overheating problems then let the level go where it will not overflow and still provide good cooling.

Steve

[lakeholme]

Dave,

Steve is right about the fill level.  With most of us used to modern day radiators, I think many of us do overfill the radiator on our classic cars.  I've seen enough coolant on show fields cleaning up after the show to know that!

But --assuming it is not a radiator overheating problem, because that radiator should work fine for your 350-- I have three questions:
1. Have you driven the car enough since the rebuild to get any trapped air out of the cooling system?  (It sounds like you have, but if you're leaking water it has to be going somewhere...  So just maybe it is air.)
2. I know it is OK, but why are you putting coolant and water?  I'd use all coolant, even without AC and even though it wasn't always done that way back in the day.  Do anything to keep rust and mineral build up out of a radiator in the long run.
3. A two parter: How old is your thermostat and when was the last time the radiator was flushed?  It could be that simple.

The next time it is warmed up --after it has cooled to where you can check the coolant level-- let the car run for a while with the cap off and see what happens.

I know I'm guilty of over kill, but I keep the fluids flushed and changed in my Camaro.  Come to think of it, when I turned 40 I had to start doing that for myself... 

[Wallace]

Have you checked or replaced your radiator cap?  Not completely filling the radiator is new to me, I have always done that.  I also use an overflow bottle to insure that any movement of fluid with the radiator will be done within coolant and will not be moving air into the system.  It was explained to me one time that any air present in the cooling system will contribute to corrosion.

[JohnZ]

Don't keep "topping it off", or it will continue to "puke" through the overflow hose. Fill it to the "Full Cold" line when it's cold, and forget about it. Coolant expands when it gets hot, and it needs empty space to accommodate the expansion; if you "top it off", it won't have the expansion space it needs, and it'll "puke" out the overflow, especially during "hot-soak" after you shut it down.

[dab67]

Phillip:

Let's see if I can answer all those questions before I forget them!!!!!!!!!!

Yes I believe I have put enough miles on the car since rebuid to blow any air out of the system. I did have that problem about 3 weeks after rebuild. Now have around 2000 miles on it.

I have always mixed coolant (anti-freeze) and water together for as long as I can remember. Never heard of just plain coolant by itself.

The thermostat is new to the rebuild and the radiator cap I replaced last year.

The radiator, I do not know the last time it was flushed or pressure tested. I haven't done that since I've owned the car.

JohnZ:  This just started doing this since the rebuild, so I'm guessing (long shot) that there is a problem with the radiator. I will only fill it to the cold fill level and see what happens.

Thanks for all the input

Dave

[262jp]

Pure anti-freeze will freeze at slightly below 0. I can't remember exactly seems like minus 6 or 8.

[JohnZ]

2. I know it is OK, but why are you putting coolant and water?  I'd use all coolant, even without AC and even though it wasn't always done that way back in the day. 

There's no advantage to using all coolant - in fact, there's a disadvantage; pure anti-freeze isn't as effective in terms of heat transfer as a 50-50 mix. Using the specified 50-50 mix provides more than adequate corrosion protection for the cooling system. It should be flushed/replaced every 2-3 years to maintain its corrosion protection properties - the anti-freeze component doesn't deteriorate, but the corrosion inhibitors weaken gradually as they do their job.

[1968RSZ28]

There's no advantage to using all coolant - in fact, there's a disadvantage; pure anti-freeze isn't as effective in terms of heat transfer as a 50-50 mix. Using the specified 50-50 mix provides more than adequate corrosion protection for the cooling system.

Here's the proof:  http://www.eetcorp.com/antifreeze/freeze_points.gif

Paul

[dab67]

Thanks CRG for all the input.I thought there was a disadvantage of some sort for pure anti-freeze. I think (actually pretty sure) that I kept putting fluid in the radiator becasue I thought it was low when in fact, as JohnZ states so eloquently, "it was puking" it out because there was no room after heating up and expanding.Have to get out of the mindset that this is a preasurized coolant recovery system. Yesterday and today I drove it about 250 miles and the level stayed the same when cold, about 2-3 inches below the neck of the radiator. This winter when I put the car up for storage, I am going to pull the radiator have it pressure tested and flush it out.

Thanks again CRG

dab67

[JohnZ]

There's no advantage to using all coolant - in fact, there's a disadvantage; pure anti-freeze isn't as effective in terms of heat transfer as a 50-50 mix. Using the specified 50-50 mix provides more than adequate corrosion protection for the cooling system.

Here's the proof:  http://www.eetcorp.com/antifreeze/freeze_points.gif

Paul

That only shows the degree of freeze protection with different ratios - has nothing to do with heat transfer. A 50-50 mix is more effective at "cooling" (transferring heat to the radiator's fins and tubes) than straight anti-freeze.