WesDe

Ok. Here in Chicago last month it droped down to -40F. The coolant in my car froze and then after I changed the coolant, but now I have coolant in the oil. Do you guys think its the head gasket or the block? There is no leak on the outside just going straight in the oil. The first time I ran the car I did not notice a problem, but now it seems like it is getting worse. What do you think? I think the coolant is getting darker too so I think it might me the gasket. It is a cast iron block and heads so I would assume it would be very hard to crack.

mattdel

time 4 head gaskets

92hatchLX

I'm surprised that none of your freeze plugs popped out. I'd put my money on a cracked head or block, head gasket would be my second bet.

HACKGT350

yeah i was gunna say im surprised your freeze plugs didnt pop i would change head gaskets

greenstreak9205

freeze plugs aren't really there to pop out when ur coolant freezes or anything. they're just there because when they cast the blocks they have to be able to pour out the casting sand. ask around and i bet that u wont really hear of any freeze plugs popping out. not saying that it has never happened but it would be pretty rare if it actually did

HACKGT350

actually they are called FREEZE PLUGS for a reason they are ment to pop when your coolant freezes to prevent the block/heads from cracking

92hatchLX

I work at a shop and it's not uncommon for your expansion plugs to pop out when the temperature exceeds the limits of your coolant. That's what they are there for.


freeze plug:
A removable plug on the block which can pop out should the coolant in the block freezes and expands. See expansion plug. The British term is "core plug."

Yes it may serve a purpose to remove the sand, but it has a much larger purpose than that.

fordguy17

ah.i always wondered what those things were for...

94gtcoupe

yep last winter it got realy cold, and my friends family never mix coolant right and it froze in all they're cars and poped the freeze plugs except the truck which blew head gaskets and cracked one of them

samseed101

Under a certainset of circumstances, the core plugcan be dislodged by freezing coolant without otherwise damaging the engine. If the coolant in the engine does not have enough antifreeze for the cold temperature encountered, it canfreeze. In the process of freezing, the water and ice expand a little. As heat is removed from the fluid part of the fluid freezes while some of it remains liquid at the same temperature. As more heat is removed more of the liquid turns solid, until it may all eventually be frozen. During the time when it is partly frozen and still partly liquid it can flow like a slushy snow cone, effectively acting like hydraulic fluid. And if a core plug was not particularly tight in the engine block, the plug might pop out and relieve the pressure, thereby preventing the engine block from bursting.

If the ambient temperature persists long enough below teh freezing point of the fluid, then the fluid will eventualyl freeze completely solid. As the coolant approaches being completely solid it will not flow very well, and the continued expansion may burst the engine block even after a core plug may have blown out. The only thing to prevent that from happening is if the ambient temperature rises above the freezing temperature of the fluid before it is all frozen solid.The core plugs may also hold firmly in place and never blow out while the expansion of the freezing fluid breaks the engine block.

So this is not the original purpose of the core plug. These plugs are simply used to close off a hole in the casting which was formed by a supporting arm of the sand "core" which was used to form the hollow cavities inside the engine block while molten iron was being poured into the sand mold. That's why they are called core plugs and not freeze plugs.

The expansion of water as it freezes is simple physics. It's not gonig to look for the "weakest link" and expand in that direction only like a gas would. water behaves quite differently. Sure, some may spill out that way, but it isn't going to prevent the ice from expanding in all other directions as well.

The fact that the core plugs sometimes pop out during freezing conditions does not mean that they were put there for that purpose. This can be confirmed by any of the engine manufacturers.