What causes blown head gaskets and how to prevent?

Just saying the odds go way up from either age or mileage and the kind of mileage has more to do with it than total miles. 500 miles of freeway cruising is nothing compared to 50 miles in commute traffic even though the first might last 8 hours and the second only 2(but often 3 or more). 1st gens are 17-26 years old and even with gently driven low miles metal parts fatigue and non-metallic ones degrade. Sometimes things last decades and sometimes they fail in warranty but the longer they’re around the worse the odds get. Lots of other parts wear out or break and get harder to replace. If you like it, keep it but it’s long since honored it’s reputation for reliability and at some point can no longer do so. There are plenty of 1st gen fans that would be happy to acquire one if you can’t bring yourself to trust it.

 

Some switched to the green after using the orange dex-cool and experiencing problems. I still use the orange dex cool in my 2002 SS Camaro. I just change it every 2-3 years and it's fine. I've heard the issue is getting all the air out of the system with that stuff otherwise it likes too gum up into brown sludge. I stick with the pink Toyota antifreeze in my Toyota's. You can get it in pre mixed gallons online pretty cheap. (Toyota Genuine Fluid

$55 00272SLLC2 Set of 2 Toyota-Scion Engine Coolant / Antifreeze Genuine 00272SLLC2

00272SLLC2 Long Life Coolant) Regular maintenance is the best solution no matter what you choose really.

 

Old coolant can become excessively acidic. They make PH test strips that you can dip into your radiator to test the acidity level. I’m a hot tub technician and I know a decent amount about water chemistry. I realize this is not actual water, but corrosive fluids are rarely what you want. You can even end up with parasitic voltage draw into your coolant if it’s really bad. You will see voltage inside your coolant with one meter lead in the coolant and one on the negative battery post. Definitely time to change the coolant if you see that and it’s over about 4VDC. Maybe a flush or three with distilled water to get as much of the old s coolant out as possible before refilling and starting over. Draining the engine block wouldn’t hurt either.

 

https://www.youtube.com/watch?v=ZUabDrfjATY

 

Is the engine block not connected to main cooling system?

 

I don’t know honestly. However in one of the tutorials I found, the brass plug in the passenger side of the block was loosened to allow a more complete drain. I’ve done this myself twice now during coolant flushes and I can confirm it works. Is it necessary, I do not know.

 

Here's what I do:

I've never pulled engine block plugs to drain coolant. You can strip threads and create a major problem for yourself. You'll still get 95% of the old stuff out doing it my way too.

1. On a COLD engine, open the radiator cap and then the lower plug on the radiator. You can also pull the lower radiator hose.
Let that drain into 5 gallon bucket. Then put the radiator plug back in and lower radiator hose if you removed it.
2. Fill radiator up with distilled water and put the cap back on. (Hard water can etch the inside of the engine block)
3. Turn the heater on full blast and start the vehicle and run it until it reaches operating temp. (this flushes the heater core as well)
4. Let the radiator and engine COOL COMPLETELY, then drain it again.
If you need to you can add coolant flush to help dislodge anything and repeat this step.

However, after draining the 1st time I just shove the garden hose in the top of the radiator on about half flow and run the engine until it drains clear from the bottom of the radiator or lower radiator hose. (much faster, less waste to collect)

5. Once you've flushed it clear and drained it again completely, close everything back up and add your fresh coolant.
6. Run the engine again with the heater on full blast and leave the radiator cap off while doing so. You'll need to add additional coolant as the thermostat opens and closes when the engine reaches operating temp. A 2 liter soda bottle cut in half makes a great funnel and allows the radiator to burp any air from the system.

7. After the vehicle has reached operating temp and the radiator is full, let it cool down and put the radiator cap back on. Bring some extra coolant with and go for a short drive around the block. Then let the engine cool completely and re-check your coolant levels after a few hours or the next morning.

You should be good to go.

 

i swear on some engines just thinking about a head gaskets failure causes it to happen.