Questions About Flushing A Radiator

[johnsmellsalot]

When you drain a radiator, you still have coolant in the engine block. So if you flush the radiator with water, you will have 70% water and 30% antifreeze when you add a 50/50 mix of antifreeze. Is there a way to get all of the water out of the engine block?

Also, what exactly does a dealer do when they "flush" the cooling system?

Is it better to just drain and refill a system to avoid an improper mix of coolant?

 

[EricF]

engine have very small drain plugs, which are usually not easy to see/find/get to.

shops hook a machine to the cooling system and just flow coolant around till it comes out clean. they use a vacuum system to refill the antifreeze so there's (allegedly) no air leaks.

You can do it the cheap way, just drain the radiator and refill with 50/50 mix. and do that every oil change for a while, it'll cycle the antifreeze mixture and over time you'll have a clean antifreeze setup and no air leaks.
doing this like 3-4 times should be more than enough to cycled the antifreeze.

 

[Rouphis]

Most engines have a drain plug or two on the engine block.

-Rouphis

 

[eljefino]

My shop flush machine never uses water, one just adds 4 gallons of 50/50 and it burps in the new and the old, out. The upper rad hose is interrupted with a bunch of adapters for the process.

I think it's pretty silly and you'd get more rust out by actually opening as many plugs on the bottom of things as you can find, but what do I know?

Drain and fills are fine and a great idea. Most let their antifreeze go too long and have problems that need flushing.

 

[cchase]

We usually just use compressed air through the radiator cap. That gets most of, if not all, the water out.

Regular draining and filling is a lot easier to do than trying to flush a neglected system. And it avoids many of the headaches.

 

[Chris142]

Originally Posted By: eljefino
My shop flush machine never uses water, one just adds 4 gallons of 50/50 and it burps in the new and the old, out. The upper rad hose is interrupted with a bunch of adapters for the process.

I think it's pretty silly and you'd get more rust out by actually opening as many plugs on the bottom of things as you can find, but what do I know?

Yup thats just a coolant exchange. It's better than leaving rusty muddy coolant in but it's no where near a flush.

Our flushing machine uses water and air to agitate the internals. This removes lots of rust, dirt etc.....Anything thats loose any way.

This flush takes about 4 hrs depending on how dirty the system was.

Once I'm done flushing I will remove the block drain and Radiator drain if they are acessable. If they are not my machine will blow air into a heater hose and out the water pump inlet.

This will remove most of the water.

If theres no drains or you can't get to them then I will use pure coolant. I will pour in the needed amount of concentrate then top that off with distilled.

I like 460 Fords and Jeep 4.0's. I can easily acess the block drain plugs on those and I can use the machines air and water to blow contaminants and the water out the holes.

The 5.9L Cummins does not have any block drains. I've done so many cars/ trucks that I know how much concentrate to add to get 50/50.

 

[HTSS_TR]

I installed Preston T-flush to the heater hose of the LS400, removed radiator drain plug and expansion cap, used garden hose with tap water to flush the coolant. After water running for 2-3 minutes I turn the water off, let the water drain from radiator until done then pour concentrate coolant into the T-flush. When the water coming out of the radiator has some coolant in it I closed the drain plug, and add coolant to get 50-50. The whole process took less than 15-20 minutes.

The car has more than 280k miles, the upper hose and some heater hoses were the only parts of the coolant system was replaced.

 

[Chris Meutsch]

I just drain and fill my radiator with 50/50 OAT coolant every 60k. I drive 50k a year so it's not like there's 10 years on the coolant.....

 

[doitmyself]

John, you didn't tell us what application your question refers to. Old/new vehicle? Clean/neglected system?

- A number of people here just drain and refill the radiator with 50/50 mix every year or two, with the idea of not letting the fluid degrade.

- If your system has unknown coolant, is a bit overdue, changing brand/type, etc., you could do multiple radiator drain and fills with good water until you have nearly all the old coolant out. This takes time, as you need to get the thermostat to open (or just take it out). I've done as many as 6 drain/fills before adding new coolant.

- The Prestone T Flush kit works great, IF you have excellent tap water. I would NEVER use my tap water in an engine.

- After that, you're looking at taking it to a shop, as others have mentioned above.

Any other options, guys?

 

[johnsmellsalot]

Well its my first car. I bought it for $2,000. The cooling system was neglected. The mechanic flushed the system and used green antifreeze when the water pump was replaced. Later on when I replaced my head gaskets, that's when I discovered that coolant remains in the block even when the radiator is drained. After I got everything back together, I changed the oil and flushed the radiator again. I got more sediment out when I did it. Right now, the coolant is bright green. I'm currently using Shell Zone.

I remember somebody at work telling me about the drain plugs. He said he had the same car. I found one on the front but I haven't looked on the back yet. I'm not going to need to flush it again until the car reaches 200,000 miles. When I do, Zerex is going in.

BTW the car runs great now. It even passed state inspections right after I got it running.

 

[user52165]

Originally Posted By: johnsmellsalot
Well its my first car. I bought it for $2,000. The cooling system was neglected. The mechanic flushed the system and used green antifreeze when the water pump was replaced. Later on when I replaced my head gaskets, that's when I discovered that coolant remains in the block even when the radiator is drained. After I got everything back together, I changed the oil and flushed the radiator again. I got more sediment out when I did it. Right now, the coolant is bright green. I'm currently using Shell Zone.

I remember somebody at work telling me about the drain plugs. He said he had the same car. I found one on the front but I haven't looked on the back yet. I'm not going to need to flush it again until the car reaches 200,000 miles. When I do, Zerex is going in.

BTW the car runs great now. It even passed state inspections right after I got it running.


And your car is a ....................?

 

[johnsmellsalot]

.......A 1999 Buick Century.
Originally Posted By: user52165
Originally Posted By: johnsmellsalot
Well its my first car. I bought it for $2,000. The cooling system was neglected. The mechanic flushed the system and used green antifreeze when the water pump was replaced. Later on when I replaced my head gaskets, that's when I discovered that coolant remains in the block even when the radiator is drained. After I got everything back together, I changed the oil and flushed the radiator again. I got more sediment out when I did it. Right now, the coolant is bright green. I'm currently using Shell Zone.

I remember somebody at work telling me about the drain plugs. He said he had the same car. I found one on the front but I haven't looked on the back yet. I'm not going to need to flush it again until the car reaches 200,000 miles. When I do, Zerex is going in.

BTW the car runs great now. It even passed state inspections right after I got it running.


And your car is a ....................?