Topic: Coolant Boiling

[neale_rs]

Fixing the freeze plug eliminated that escape route so now it comes out the cap. 

On a couple of older vehicles with carburetors I've had overheating problems due to the timing being off even though there was nothing wrong with the cooling system.  Could this come into play here?

[reddogg]

I had issues from the beginning with the probe installed in the fins. I drilled and tapped the thermostat housing, mounted the sensor. No troubles so far. It would probably be better mounted in the Radiator tho.

[sharpxmen]

water should never come out of the radiator cap unless it is not screwed in all the way (tightened). what's the temp like at the gauge?

[neale_rs]

water should never come out of the radiator cap unless it is not screwed in all the way (tightened). what's the temp like at the gauge?

This is a very important point ... Is it actually overheating or is it just a problem with the cap or the neck of the radiator where the cap screws on? 

[Saggy]

This is a very important point ... Is it actually overheating or is it just a problem with the cap or the neck of the radiator where the cap screws on? 

I had this same thought.  I replaced the radiator cap and had the same result.  The cap fits around the neck, turns about a half turn, pushes down and turns the rest of the way so I don't THINK there is a problem with the neck.  Can anyone think of a better way to validate the fit than 'feel' though?

water should never come out of the radiator cap unless it is not screwed in all the way (tightened). what's the temp like at the gauge?

Now that I understand how the overflow works (it's actually NOT magic!) I get where you're going with this.  I will grab a radiator pressure test set and report back.

Thanks...yet again...for all of the help.

[neale_rs]

I had this same thought.  I replaced the radiator cap and had the same result.  The cap fits around the neck, turns about a half turn, pushes down and turns the rest of the way so I don't THINK there is a problem with the neck.  Can anyone think of a better way to validate the fit than 'feel' though?

Now that I understand how the overflow works (it's actually NOT magic!) I get where you're going with this.  I will grab a radiator pressure test set and report back.

Thanks...yet again...for all of the help.

Also check the temperature, is it actually overheating?  If the cap or neck is not holding pressure then the coolant will boil at a lower temperature than if it was held at a higher pressure by the cap. 

[sharpxmen]

I had this same thought.  I replaced the radiator cap and had the same result.  The cap fits around the neck, turns about a half turn, pushes down and turns the rest of the way so I don't THINK there is a problem with the neck.  Can anyone think of a better way to validate the fit than 'feel' though?

Now that I understand how the overflow works (it's actually NOT magic!) I get where you're going with this.  I will grab a radiator pressure test set and report back.

Thanks...yet again...for all of the help.

ho problem - make sure the cap you got is the right one (is it new?) - some radiators have a built-in overflow tank at the top and there is no gasket on the cap for the outer (top) rim, just the bottom, yours should have a gasket on both bottom and top so when the coolant expands and makes it past the bottom seal will go into the overflow and not make its way around the cap top seal. Another thing to check is if your tube from the radiator to the o/f tank is not plugged, i've seen this with old rubber which breaks down and gums up the tube.

Also check the temperature, is it actually overheating?

yeah, i was wondering the same thing (if it's not just the liquid expanding)

EDIT: is it going past 210 and the fan not kicking in?

[Saggy]

No.  That has been the funny part.  I see the temp gauge fall when it gets just past half-way and it stays within range.

Actually, as I remember back, I put a rad pressure tester on it before I hooked the tranny back up.  I never could get it to hold pressure.  I dismissed it as a bad tester because it wouldn't seat properly on the neck.  I can't believe I'm just putting all this together.

So, what happens if the neck somehow got bent a little out of shape?  I don't know how that could have happened...but I do leave the hood wide open when it is in the garage so I can disconnect/reconnect the batteries.

[neale_rs]

Sounds like this might be figured out.

New radiators are not too expensive, you can even get all aluminum ones from eBay at good prices.  You might also be able to reshape the neck.

[Saggy]

Well crap.

I'll check it out tonight when I get home.  Sounds like it could be a candidate for the oxy torch and a set of needle nose.

Will report back.  Thanks to all.

[neale_rs]

This looks like a good deal:  http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=140713646453#ht_500wt_1202

[sharpxmen]

Well crap.

I'll check it out tonight when I get home.  Sounds like it could be a candidate for the oxy torch and a set of needle nose.

Will report back.  Thanks to all.

don't use a torch on it, you'll melt the solder if it's not plastic, if it's plastic that's a no-brainer - Is yours plastic tanks or brass tanks? I would just buy an all aluminum one (with welded tanks) double row from ebay, got mine for about $125 shipped (around that, was 2 years ago) and i can't be happier.

[Saggy]

It is pretty new.  Just put it in two or three years ago.  I think the neck is brass.  Assuming that really is what the problem is, hopefully it will be soft enough to bend back with pliers.  Otherwise, looks like another new radiator may be in the cards.  Seems like a waste!

[sharpxmen]

It is pretty new.  Just put it in two or three years ago.  I think the neck is brass.  Assuming that really is what the problem is, hopefully it will be soft enough to bend back with pliers.  Otherwise, looks like another new radiator may be in the cards.  Seems like a waste!

check the cap, there should be a gasket on the top side as well - see if that's missing, should be quite bent out of shape if deformation on the neck is the problem.

[Jeffy]

Damn, man.  Nice write-up.  Will definitely study that to see what I can borrow from it.

I swapped out the thermo switch with the constant temp Hayden 3652.  It is supposed to come on at 185 and off at 165.  It didn't fix the problem.  Coolant still comes out from the cap.  By the way, I also tried a new cap just to make sure it wasn't a worn spring or gasket on the cap.

The probe is pushed through the radiator fins just below the upper hose.  It has always kicked the fan on in the past.  Not sure what has changed here.  I have noticed that I have more coolant in the overflow container than usual.  It may even be just above the line.  I don't understand how the coolant overflow works so not sure whether this could be a problem or not.

Could this be as simple as removing some liquid from the overflow container?

How is it wired?  Like I said before, if you have the thermo switch on the fan side of the relay you'll  overload the switch and melt it.  Even if you have it wired correctly, you can end up melting connectors.  This is why I switched to a CB over a fuse.

So in otherwords, make sure the fan actually turns on.  Bypass the thermo switch.