[Long] I’m just posting this for anyone who might be curious, so there’s no question. I suppose its something in the family of OK4450’s experiments with acetone in his gasoline (if I’m remembering that correctly).
Back in November my '97 Escort developed a small head leak. (LX wagon, 2.0L SOHC engine. Car has 310K; engine about 200K). The symptoms were an occasional, temporary misfire (cyl 2 - P0302) upon cold start up if the temps got down to less than 40F or so, relatively minor coolant loss, mostly external but some internal, and a small amount of bubbles in my coolant overflow.
The car is in remarkably good shape for its age/mileage and the heads on these are not hard to do. But I simply didn’t have the time. So given its age and mileage I thought, why not give mechanic in a bottle a whirl? It seemed a good excuse to do some first hand observing.
First I checked out the straight sodium silicate bottles (blue devil and the like) to see how you’re supposed to use it. These are apparently incompatible with coolant. So for all of the pre-flushing and post-flushing you’re supposed to do it takes a long time - at least to go according to directions. So I quickly figured out that if I followed the directions on the bottle it would take me longer to apply the sodium silicate treatment than it would to just fix the head - so nothing gained there. Time was my only issue.
I found a different type from a major manufacturer of stop leak-type products that contains sodium silicate, but also a bunch of other stuff, and is supposed to be compatible with coolant. So to use this one, you just dump it in, get the car up to temp and then let it cool down all the way.
So I bought a bottle and added half, which is the “dose” for a smaller 4 cylinder engine. I have to tell you that it actually made me a little nauseous pouring that stuff in. Its gloppy, and oddly colored. I’d say “bottle of monkey snot” might be a good description. All I could say to my wife as I poured was “I can’t believe I’m doing this…” But what the heck.
Short story: it solved the cold misfire and coolant loss. However, it left a combustion leak into the cooling jacket - but at a tiny trickle. I’d have to stand at the overflow and watch for a good minute, and every once in while it would send out a little bubble or two. I did borrow a block tester and make sure it was combustion gas. Luckily the radiator cap is the highest point, so it mostly just purged itself as it went. But on shut down the gasses would cut off the siphon effect for the overflow back to the radiator, so I did have to keep an eye on the coolant level in the radiator - sometimes pulling it back from out of the reservoir.
I got in touch with the company & they said “might as well just add the other half of the bottle.” So I did, and got no change.
Knowing full well that it was a bad idea, I continued to drive it for the next 3.5 months and about 8000 miles. It was fine. Ran well. Never a sign of issues with the temps. The heat had no problem. If you didn’t know there was a problem you wouldn’t have reason to suspect one.
But, a couple of weeks ago, the combustion leak suddenly expanded (first hot day of the year and I had to drive it relatively hard?), and now my reservoir looked like a tea pot at full boil. (Still ran ok and no signs of coolant loss).
So that was that. Luckily my wife had a few days off from work (only 2 cars), and I could make the time. So I replaced the head gasket. (Back to normal now. Could be a long story, but all I could find was a small separation of the sealing ring at one side of cylinder 2).
The thing is that I was all prepared to take pictures of the “aftermath” as I tore it down - pics of goopy glops of crud clinging to the internals of the coolant passages. That’s what I was going to be posting. But I didn’t take any pictures - there wasn’t anything to take pictures of. It was really odd. Not even the thermostat had any goop or buildup. Its in there somewhere as I was cleaning stuff off the radiator cap after adding it - its puts copper dust and something that seems like wet cardboard in there. I have to assume a bunch of stuff may have settled at the bottom of the radiator. But I guess if you have a clean radiator its not enough to matter. The company says it won’t goop up the cooling system - I suppose I have to believe them.
BUT: and an important note for any passerby who doesn’t know anything about cars, my cooling system is regularly serviced and always clean on the inside. I don’t have a crud filled radiator (maybe a little now) or heater core or anything else. A lot of the bad experiences with these products, I think, might come from people who neglect their cooling systems which contributes to a head gasket failure, and then they add this monkey snot to a crud filled system. That seems like a recipe for disaster.
After all of this, I guess I didn’t learn anything I didn’t already sort of know - these things might help as a band-aid and limp you through an issue. But the term “fix” is certainly a misnomer. That said, it did limp me through exactly when I needed it to. I’d be willing to try it again under similar circumstances. I have no reason to fear it will cause more problems than it solves.
- 1 car, 1 experience, so take that as you will.