July 4th night,my T-stat shut up tight and boiled my antifreeze and water thus blowing the overflow lid off and letting the water out and letting it steam. I replaced the t-stat and filled her with coolant. But now,Shes really thirsty and water doesnt stay in her long. Tommarow I'm gonna do a compression test and see whare its leaking out. Have any of you guys ran into this? If you have,Was it expensive to repair? Could this of lead to engine damage? Theres' no water in the oil.

Thanks in advance.

 

check the frost plugs in the side of the block for starters and see if you are leaking out of them.

 

If there is no water in the oil and no water or steam coming out the tailpipe, check for a leak at the waterpump weephole, and all the hoses. If that checks out I'd also check the radiator cap, radiator and heater core too, as well as the freeze plugs in that order.

 

What are "Freeze Plugs"?
I put water in the radiator and after a few bubbles from air trapped in the system,the water went down. Then after some more water no bubbles,just went down like it was being drained But the ground undernieth is dry. Could it be its just water draining into the system? There was a hose loose on top of the T-stat housing,but I tightened it up. Also,On the Housing neck (whare the hose connects) I seen rust,like it was in the water,But its not in the hose.

 

Freeze plugs are little round metal plugs usually made out of brass. It seals the holes made into the engine block and head when it was manufactured. It also serves to save the engine block from cracking when the water in the engine freezes. The plugs pop out relieving the pressure. before the engine cracks open.

A lot of air can be trapped into this engine. If you have super cooling it can take up to 3 1/2 gallons just to fill it up. With the engine cool, take the radiator cap off, and run the engine to normal operating tempurture, shut off, add 50/50 coolant/water into the system. (70/30 coolant/water in alaska, Colorado, etc.) And replace the cap.

It's normal for some of the water to escape over time, over several months with expansion tanks, (shorter with engines without tanks) but not drasticlly. Check the coolant on a cold engine once a week for a few weeks (or more often if you notice the guage reading hotter than normal), then once a month for good measure topping off when nessessary.

Hope this helps.

 

[QUOTE=Cruiseomatic]What are "Freeze Plugs"?QUOTE]

Freeze plugs are steel or brass, round stoppers that are press fit into the outside of your engine, blocking the coolant. Their pupose is to pop out in the event of a frozen block.

Have you ever put a full bottle of beer in the freezer for a quick cool and forgot about it? If so when you found it a day or so later it had exploded. Thats what happens to engine blocks or anything else filled with frozen water in a confined space. Water pipes for instance. The idea is better to have to pound in a new freeze plug than to have a ruined, cracked, block. They can be a great nuisance but still a good idea.

 

I don't know if I have super cooling,it has A/C.
And ever since we replaced the T-stat,it gets to N or O in normal and stop. And I guess when the T-stat opens,is when the temp drops again.
Thanks for the info on Freeze plugs.

 

Your temp running betwee N and O of normal is good. And my rule of thumb, Anything above the M needs to be checked out. and above the L means shut engine off and pray. And yes, when you see the guage drop the t-stat has opened up.

Yours is equipped with supercool, cause it has a/c.

1981 300 I6 specifics on cooling systems. Could be different on earlier or later 300s.

Standard cool...

Small Radiator
Flex fan
Fan guard
capacity 13 quarts


Extra cool...

Small Radiator
Clutch Fan Non-thermal
Fan guard
capacity 13 quarts

Super Cool... or standard with A/C

Big Radiator
Clutch Fan Non-Thermal Non A/C
Clutch Fan Thermal A/C
Fan Shroud
capacity 14 quarts


Hope this helps.

 

I've got an '89,so it should be pretty close.
I had to run a little past L for about 10-15 minutes. Oil isnt milky like I said,doesnt seem burnt,Engine never smoked either. She runs a little rougher now since then,but it could be that crappy conoco gas I had to put in her. Im praying The engine is ok. Sounds the same looks the same,oil pressure is up in normal,temp stays nice and cool. I just went out to check the coolant leverl,its not in the neck whare i left it,but the ground is dry and its right under the neck. Maybe the hose was the leak.
But I still cant figure out the rust........ Its only at the T-stat housing neck. Not in the hose or anywahre else that I can see.
Thanks for the help.

 

coolant passages get quite rusty that's why auto places offer pressure flushes for the coolant in your motor. It seems every one has described to you what freeze plugs are so i'll say just this i beleive there is 4 on your motor 1 at the rear of the block which you cant see and 3 at the side under your intake manifold. I'd check to see what yours look like . Usually if it's leeking from a side plug in the block you won't find a wet spot on the ground because, some gets caught on the oil pan lip then slides back across the oil pan then transmission so on.....

 

I hate to burst bubbles (not really), but freeze plugs are not for the purpose of freeze protection, and I know from personal experience that they do not work in this mode. In the casting of blocks and heads, holes need to be cast in various places to support cores and to make room for machining operations. Such a hole is called a freeze (I think an "i" is involved in the spelling, but have been unable to verify that so far). After the block is machined, plugs are tapped in to plug the holes - thus "freeze plugs".

Back to coolant leaks, I have been chasing one down in my '94 F150 for a while now. It ended up being the radiator, at the seam between the plastic tank and the aluminum cores. I had a shop put me in a new radiator, and still had a leak. Took it back and they told me it was coming from the housing that covers the timing chain. (My 300 six must be the only one ever made with a timing chain, I guess. I just don't have it in me to walk into a parts store and ask for a new one - couldn't keep a straight face.)

But, it makes me wonder if there is a water passage somewhere within that housing. I can't tell from Chilton's/Haynes's pictures of the housing, but the gasket certainly doesn't look as if it seals water anywhere. It also seams that such a leak would show up in the crankcase. Am I totally missing something?

 

here's my problem, mine always runs hot! my overflow tank is almost full now... whoops! haha, thinking about just puttin in the v-8 radiator, but don't really want to buy a new core support... or I have an electric fan that I could put on, but if my manual one works (or at least I assume it does, it definitely spins) why put on the electric fan?

 

hello,

any idea on what to use on this? i broke the over flow nipple off the radiator plastic part, i tried jb weld no good craked and leaking bad any idea's or simalier problem? any luck on repairs dang radiator 210 bucks.

thanks Glue.

 

A properly installed electric fan will give you far superior cooling. When at a stop with a conventional fan, the fan is turning at a minimum...about 750 rpm. It is turning the slowest when you need it most! With an electric, it is turning full force (moving 1400--3500 cfm!) when you are stopped. That is double or triple the amount of air moving through your rad. They work great, and can be installed with thermo. automatic control. Just don't use the push-thru ties system that can weaken a rad. core.

For about $30 you can find one to fit at a junk yard, and make some simple brackets to mount it.

 

Reply to ONGLUE:

Nothing but replacing it is going to fix it satisfactory. There is too much heat and expansion for JB weld or other epoxys to stick.