I've always changed my own oil, but I also want to change my antifreeze.
I just want to drain and fill, not flush. Is it just a matter of draining the radiator and adding new? Should I do this while the radiator is hot, or cooler?
and where is the plug?

 

If you plan to change to DEXCOOL you MUST flush.

DEXCOOL is not compatible with the usualy green stuff. If you mix the two, like in drain but not flush, you will get jello in your cooling system. Most cooling systems will only drain about half to maybe 3/4 of the fluid. There is always some left in the system somewhere. So flush with clean water, several times.

Depends on how mechanically inclined you are whether this is easy or not. Most engines have a drain petcock on the bottom of the radiator. It usually is a spout or plug with wings on it that you turn out to drain the radiator. But to do a thorough drain you should also pull the drain plugs on the side of the engine block. However, many newer engines don't have drain plugs, rather they use that spot for knock sensors. A bit of a pain to remove those in some cases.

I prefer to use a backflush system like Prestone makes. This allows you to just hook up the hose and let the water flush out the system.

What I would do is drain as much as I could from the drain petcock on the radiator. Do this while things are cool or luke warm, otherwise you could get burned, badly. Then install the Prestone backflush system, quite easy on most cases. Then follow directions and let the system flush clean water thru the engine. I like to do this with the engine running and heater on high. I do this till the water comes out clear. Then I close up the drains and let the engine idle with the water in it until the engine comes up to temp. Then I back flush again. I may do this several times.

Usually then I use a ten minute chemical flush and repeat the back flushing several times. Then I let the system drain as much as possible.

Then I figure out how much antifreeze is needed and add that first. Then I top off with wter, I use distilled for low mineral deposits. The reason I add anti freeze first is that as I said, there is always some water left in the system. So if you add the correct amount of antifreeze first then top up with water, you know you have the right mix, usually 50/50.

You should also bleed any air in the system, if you have a bleeder. Usually the bleeder is a screw on the top of the thermostat housing that you crack open and let the air out while the engine is running.

You should top up the fluid every day for a week or two since as the air gets out of the system, the fluid level may drop.

NEVER EVER remove the radiator cap when the engine is hot, you could get a very bad steam burn which is much worse than just boiling water.

OH and don't believe the hype on DEXCOOL that it is good for 100,000 miles or more. It will be dirty at 50,000 or less and in my opinion should be changed then.

Good Luck,

Jim Henderson

 

First of all, I assume this is not a Ford. If it is a Ford, you should not be using Dexcool. Also, you should never open the cooling system when hot.

The answer to your other questions is, "It depends". If your coolant is fairly new and your system is clean, you can just drain the old and replace it. However, this is rare and usually you should at least flush it. Depending on what type of vehicle we are discussing, there is normally a drain **** or plug at the bottom of the radiator. However you won't get all the coolant this way. That's part of the reason to flush. Its also the reason to use full strength instead of premixed antifreeze. If you use a premix when changing, it will be diluted by any remaining water or old coolant and you won't have the freeze and anti corrosion strength you expect.

 

I would like to add that, while I usually like the Prestone backflush system, I would recommend against it on certain new vehicles and particularly to an inexperienced installer, unless the heater hoses are also being replaced. This is because the heater hoses are located where they are difficult to splice into and seal without leaking onto a vulnerable part. Ford F150's with COP's are the best example.

 

I tried Dexcool in the BMW and would recommend against it. There are a lot better "long life" coolant formulas out there. Dexcool does not protect aluminum as well as traditional green coolant. The latest Ford-spec (yellow) coolant from Zerex is what I use now.

Jim

 

I know a lot of people, myself included who have had experience with head gasket leaks when using dex cool. I recommend against it. If you want the long life stuff, use the gold ford (zerex) or Zerex has a green long life. I usually use either Zerex green or Durex from Fleet Farm. The durex is cheap and never had a problem with it. Use distilled water. I used to use our well water and it didn't take long for the radiator to build up minerals and clog.

 

I wish I'd found you guys a couple weeks ago. I got a beautiful '97 Park Avenue Ultra with 100,000 miles on it. The records showed the Dexcool was changed at 60,000 miles, but it looked "sooty" to me. I agonized over whether to go with the Zerex/Ford Gold (as in my F150), or stay with the Dexcool.

I decided to stay with the Dexcool mainly because it has no silicates, and I hope to postpone water pump replacement as long as possible. All the other formulas seem to be "low silicate" (whatever that is). I can't know for sure, but I think that most of the Dexcool problems are due to mixing with other types, or too lengthy change intervals. Besides, by now GM has had millions of miles of experience with Dexcool and if I go to the other route, I'd be pretty much on my own.

 

Here is the problem I have.. All I want to to is drain my antifreeze, refille with new, burp it, and that's it. But my mechanic tells me that I run the risk of cracking my engine block if I don't do it right such as an airpocket not getting out of the system correctly. Is this a line of bull, or should I be fine just simply draining it and refilling?

 

He's just trying to get some business.

 

Line of bull. Only way to damage the engine block might be if you ran the engine with no coolant and ignored the warning lights.

You should bleed the air, but over time the air will bleed itself. Only in poorly designed cooling systems will you get bad enough air pockets to really cause problems. That or if you never warm up the engine enough to get the thermostat to open and then force coolant under pressure thru the system which flushes out the air.

Changing coolant is one of the easier maintenance tasks and well within the capability of even a novice mechanic.

One warning. Antifreeze is toxic. As little as a table spoon will kill a dog or small child, it destroys the liver. It is sweet so such creatures have been know to lap it up. So make sure where ever you drain it that it does not make puddles that wandering creatures can find. Most places recommend dumping it into the toilet at home. The bacteria in most treatment plants love this stuff, burp. Some septic systems also love it, but could be overloaded. You might check with the local yokels first before dumping it to make sure it is safe and or legal to do so.

Good Luck,

Jim Henderson

 

One thing I might add too, is after flushing your cooling system, drive the next 10-15 miles with your heater on. Unless it is summertime hot, this will help remove any air in the system sooner, rather than later. Always check your coolant level, the first few times, after the engine has completely cooled off (overnight shutdown) Jim, are you speaking of the Zerex G-05 coolant? if so, I use it as well, with excellent results. Also, change your radiator cap every 3 years or so. It's cheap insurance, and I have always used a 13 lb. Motorcraft cap, with no heating problems during 100 degree+ summer heat and freeway driving, with AC on. Ed

 

there is no point in just changing it with out a flush. you need to flush it. dexcool is junk and needs ot be flushed. never do it when hot.

 

Ed,

Yes, its the G-05 coolant. I mix it only with deionized (or distilled) water. The BMW has a marginal cooling system for this part of the world and needs all the help it can get.

If I wanted to do a quick drain and refill on a truck that has green coolant, I would just continue to use the same stuff. For an older truck with cast iron heads, and if you change it every 2-3 years, there is nothing wrong with the traditional green. On some vehicles, there is no drain plug and you just have to remove the lower radiator hose. About 1/3 of the old coolant will remain in the engine and heater core without a complete flush.

Jim

 

From what I have read in trade mags like Motorage, if you are just adding coolant, you should use what's already there. If you were to add a different type nothing bad would happen just that the rust inhibitors would be different and you would only get the protection of the one with the strong concentration.
I never heard of antifreezes gelling up?

 

As far as antifreezes gelling up, that is the experience of several members on a chebby website(NAISSO) that I participated in since 1997. Every year around winter we had the flurry of "No heat from the heater" threads. It usually turned out to be Dexcool plugging the strainer and core.

Some members tried to get around the Dexcool issues by using green stuff instead. Many of them got jelly like stuff coming out when they finally drained the system. Not saying for sure it was the mixture, but a lot of people got jello. Experience told us that you MUST drain and flush Dexcool completely if you want to go to another coolant. And several recommended against any sealant tablets such as recommended by GM.

Also there as a big test and study put on by independent radiator shops and sponsored by GM and Texaco(makers of a Dexcool fluid). They had several conclusions. Most of the problem with Dexcool was contamination and precipitation due to air in the system creating "dropout zones" and rust. But they also noted gelling when green stuff was mixed in. I can't recall all the details and whether this was always the case. But enough members had the problem that that website pretty much universally recommends against mixing. Also I believe the study had the same recommendation.

The couple times I did drain dexcool, it had no gelling but it was murky at far fewer miles than the fabled 100K change interval. It did leave a very definite bathtub ring in the reservoir that I was never able to clean out.

Good Luck,

Jim Henderson