Re: notorious subaru head gasket failure coolant overheat problem. I thought I’d let you know how desperate I am and how using brake fluid for coolant worked the first and only time I’ve tested it so far. It didn’t over heat for an hour and a half continuous multi speed driving with one stop to idle at wendy’s. I’m not recommending it but thought you would find it interesting. After I post this I’m going out for another hour and a half mostly highway. I'll let you know what disasters if any happen and whether I’m still alive. If I don’t post again you know what happened and how to act accordingly. Even if I post again you shouldn’t try this. I beg you not to try something this crazy and foolish. But, if I've entertained, something good came out of it. My loss your gain. I mean it, don’t do this!!!! You might be exploded, you might die or be crippled, maimed and blinded for life and everyone around you for a 15 mile radius. This is extreme experimenting.
So, I had typical head gasket failure overheats and bubbles in the reservoir. Intermittent over heating. But finally it would over heat after about 15 minutes local street driving.
In desperation ‘cause I’m broke and I love this car I decided on the apocalyptic method of survival, since lately it’s been feeling kind of apocalyptic in the world, thought it was appropriate. Instead of throwing the car away because new head gaskets are so expensive and such a cost benefit gamble I decided to experiment with brake fluid as a coolant. As opposed to mineral oil. I dried out the system with a hair dryer and warming the engine without coolant to about the normal temperature to get as much moisture out the system as possible while running the hair dryer stuck in the thermostat hole on high heat and high volume.
I took it out for an experimental drive with brake fluid for coolant today and it worked fine for an hour and a half drive. Hasn't gone more than 20 minutes without overheating previously. Just enough time to get to work. I drove the experiment at highway and street speeds. It took a long time for the fans to finally come on after the temp gauge went above normal but not too far. When the fans came on the temp came down to normal. It only peaked twice and generally stayed normal. I’m willing to drive it even if the gauge is above normal a little but I didn’t have to. Don’t know why it didn’t spike again. Could be there was some water in the block and it boiled off. But really don’t know but am very happy about no overheating when yesterday it was overheating every ten minutes. Overheating meaning serious high temp spike which ‘causes me to stop, kill engine and open hood and cool engine for 15 minutes.
Why brake fluid? Brake fluid is similar to glycerol and it has a high boiling point and flash point and autoignition temperature. Better than mineral oil in that regard. I’m iffy about how the brake fluid will treat the aluminum but the master cylinder is aluminum so what the heck, brake fluid is supposed to have corrosion inhibitors for steel, at least, maybe it will work for aluminum too. Concerned about Aluminum in in the engine and the new radiator core and nylon might suffer from brake fluid too for that matter, and also rubber heating hoses, and aluminum in heater core. I figured there's rubber in the brake lines and cylinders so chose that over mineral oil because I think mineral oil is likely to hurt the hoses. Also radiator hoses handle antifreeze, ethylene glyclol, break fluid is diethylene glycol. Might treat radiator hoses just as well. Don’t know for sure and may try mineral oil if the brake fluid worries me that way or for other reasons. Also may abandon the whole experiment and the car. We’ll see.
I also decided on brake fluid over mineral oil because it has a higher specific gravity than water and antifreeze, oil has a lower gravity. I reasoned more density would transfer heat better. And a higher boiling point would keep the boiling down which kills heat transfer. Plus I'll keep it pressurized and thermostated which should raise the boiling point even more. I hope there will be no explosions which is why you should never ever try this hair brained idea. Let me do it for you. I’ve always been a risk taker. Brake fluid is flamable and has an flashpoint. But, so does antifreeze. And mineral oil. Brake fluid is higher. And again I think what the heck.
While I was filling it before I took it for the hour and a half test drive. I ran the engine and heated up the brake fluid I'd gotten in there. I got a very high spike in the heat gage after about a half hour idling while slowly filling to top off the brake fluid. I wanted the thermostat to open. Fans came on but spike did not come down disappointing, but I did notice the engine did not sound over heated. I turned off engine and kept filling with microwave heated brake fluid figuring what the heck I’m in this far. I stopped the microwave every minute and opened cap to release any pressure. I warmed a quart of it to about 100 degrees in 4 minutes. Used that to top the radiator to the brim. It took a while but I got there. I have reservoir in line as is typical so took that out to get all moisture out and rinsed it with a little break fluid and dumped that with any moisture the couple ounces of brake fluid could grab, and reinstalled. Dot 4 Brake fluid $4.50 a quart loves moisture so I will have to deal with that if I keep the brake fluid in. I figured if I put the cap on the first click in wouldn’t hold pressure and the water might steam off into the reservoir before the break fluid does. Otherwise I might let the over flow dump on the ground for a trip or so once a month to get moisture out. Haven’t decided yet. Don’t even know if the experiment will last for month or not but I’m encouraged by today’s foray. I’ll keep you posted. dadob
Edited by dadob, 08 January 2011 - 08:16 AM.