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Horrible 2002 Honda Civic problem! Ever heard of a Freeze Plug?

My Honda Civic had serious problems last summer (at 85000 miles). The thing suddenly stopped running I mean completely went dead when I was driving it down the street about 30mph. Turns out the antifreeze and oil had mixed through the whole engine cause a “freeze plug” between the heating/cooling system and lubrication system had popped out under the engine head. I don’t know anything about what’s under the engine head this is just what the mechanic told me. They said they “epoxied” the plug back in place and charged me 1200 dollars for a bunch of system flushes, also replacing the radiator. However they didn’t get the heat working because the mechanic said maybe the heater core needed fixing and flushed around that area a couple times but obviously didn’t do a very good job since the heat didn’t work for the first half of winter. That was last August.

The car now ran fine, and there was a question of whether the heater would work. I didn’t do anything to fix the heat at that time. It worked when you drove at 55mph or higher for at least 15 minutes, but if you parked and let it run while you waited someplace after that it wouldn’t work at all while you were parked.

I finally got sick of freezing as I drove and took it to a different radiator place. It cost 100 bucks and they fixed it fine by flushing the radiator “about a hundred times”. The heat now worked fine and no heater core was necessary.

My main question is this: What is a plug that can pop out doing between the antifreeze/cooling system and the oil. Wouldn’t it make sense to have absolutely no possible point where these major engine fluids could run together? This seems like a badly engineered engine to me. I also want to know if anyone else thinks Honda should recall a car with this sort of thing happening to it.

Freeze plug is actually a misnomer; the correct term is block plug.
Every car made has block plugs in them, both in the block and cylinder heads, and they must be present. Without getting into too much of a detailed explanation these holes where the block plugs fit are formed during the casting process when the engine block and heads are cast from molten metal. When the mold is disassembled the holes are what allows the loose sand which is used in the mold to be removed from the block or head casting.
That’s the real reason; the fake reason is that they’re designed to pop out and prevent an engine cracking if pure water freezes inside the block.

What you have suffered is a pure fluke. This kind of thing seldom happens and you just happened to be it on a certain day and no recall will be issued on a block plug.

Thanks for your response. I have a further question about this. My big problem is that this happened again today. I was driving and heard a ssss ssss ssss sound in the engine and 200 yards later as I was turning the car dead stopped in exactly the same way it did last year. Now I have already had the car towed to a local honda dealer. My question is does this seem like the sort of thing that can be fixed with an epoxy or does it require an all new engine? If it can be fixed with an epoxy then perhaps the new thing is due to my running up on a curb when I parked this morning. Could this have happened today because of a damaged radiator, I hit the curb kind of hard.

The term freeze plug comes form the days when that was exactly what it was. a plug that would pop out if the water froze in the engine. It was to keep the engine from cracking. If you lived in Vermont in or before the 50"s, you would know this. Modern antifreezes eliminate the need.

As a metal caster who used to cast cylinder heads for the big 3, the hole is not needed to let the sand out. There are many water jacket openings between the head and the block that let the sand out. The hole is caused by the ends of the sand core. It is what the core setter uses to place the sand core in the permanent mold and hold it there as the mold closes.

I have never seen a freeze plug (the term is still in use) between the head and the block. But even if there is one, I don’t think that is the root cause of your problem. I believe that you have a crack in either the head or the block, or that the head gasket blew for some reason and the mechanics didn’t check both the head and the block mating surfaces for flatness.

Generally either of these are caused by overheating the engine, but the engine could have had a casting defect that just didn’t show up until now. An example would be porosity (micro-porosity) in the casting that wasn’t bad enough to get caught in inspection and pressure testing. Also the core could have shifted slightly and left a water jacket wall a little thin.

The first time this happened, the oil and antifreeze mixed completely till it was “milkshake”. There was gunk in the oil areas. There was the same gunk in the antifreeze areas. I checked the dipstick, I checked the radiator which was leaking from a hole that got blown in it. The nasty brown mix was everywhere. There was no crack in the head or block, I have been using the thing successfully since last August, I have put 12000 miles on it since then. If there was a crack in the head or block that wouldn’t have been possible. Unless you mean after the curb today.

It’s not a good idea to design that kind of thing where it could so quietly destroy an engine. It didn’t destroy it but it could have. Most engines don’t have that situation. If they used epoxy, I think it was the wrong thing to do. Epoxy is plastic and it doesn’t hold up to heat at all. In fact, if you want to loosen up epoxy so you can separate the parts, you apply heat. I have fixed golf clubs by doing that. A heat gun is sufficient to melt most epoxy. The best way now would be to use the right stuff or change the head, because it is likely to fail again.

Needless to say I am not too thrilled with this repair job. I remember when he was telling me about the repair job he did I was thinking “why didn’t he tell me BEFORE he did this?” I agree about the epoxy and I knew then as I do now that epoxy sounds like a bad idea there. He said it was some high power epoxy that is made for the application. I still thought it was a bad idea because I would have rather had the repair done right or at least the problem explained before he just put it together again with a quick fix that wouldn’t hold up. I was focused at that time on the timing belt which I thought he should have replaced while he had the engine apart (they explained to me they didn’t go far enough into the engine for that).

I suspect the mechanic fixed the car that way (without taking time to call me) so he could get space in his garage. He happens to be the husband of an old girlfriend of my wife. He will claim that I told him to do a cost effective fix but I am not stupid about what repair I want and wouldn’t be stupid enough to want a repair that would obviously just break later.

I’m having to theorize a bit here but from memory the cylinder head may have a few plugs in the valve train area. If one of those plugs comes out then coolant will instantly pour into the valve train area and then down into the oil pan.
I read this as the mechanic pulling the cylinder head so do I assume he pulled the head and then found this loose block plug after the fact? This of course probably led to head gasket replacement?

Your mechanic made 2, at least, mistakes here IMHO. One is that epoxy, or any sealer, is not needed on block plugs.
The other is that he reused the plug that originally came out. One NEVER reuses a block plug. When a new plug is installed they can be staked in place with a hammer and pin punch if need be; but no epoxy no matter what type it is.

One real issue you have here is the milkshake oil. Coolant is a lousy lubricant and when mixed with engine oil will cause some engine wear problems; crankshaft bearings, cam lobes, valve adjusters, cylinder bores, etc.
My opinion is that your entire engine has some damage; the only question is the degree of the damage.

As to why the plug came out and the radiator was ruined I can only theorize that the car was overheating and seriously overpressured the cooling system. It’s possible that if the radiator cap has not been off in a long time that the rubber cap seal could have been sticking to the radiator. Instead of a cooling system that releases pressure at say 15 PSI the release pressure could have been much higher due to the cap not functioning properly.
I’ve seen a few caps in the past that required a large pair of pliers to remove and the seal was left sticking to the radiator.
Hope some of this helps anyway.

Yes that’s what they said. Pulled off the cylinder head and saw the plug was out. Then put the old plug in with epoxy. Learned my lesson about taking the car to those people. Never again.

On a happier note, it looks like the plug may have not popped out YET the oil still seems alright. The radiator is on empty though, after the curb incident yesterday. I took the car to a radiator repair garage for the present problem. Will see next week what is up with it.