How to flush cooling system?

[Carlostrece]

I have questions about flushing my 97 Buick Park Ave coolant system. I was going to have a local mechanic do it, but I've decided it's best to pay my cousin do it.

The 8 year old 50/50 Dexcool currently in it has only 4000 miles and still looks orange and clean. However, today when I called my local mechanic, his receptionist/wife/office-manager told me her husband used Kelso WA city water to flush and refill it 8 years ago. The Kelso city water is good quality and not hard water, but it does have chlorine and flouride and maybe a few minerals.

That ^ reduced my confidence in that mechanic and his shop.

I know another mechanic in another city 13 miles away who'd probably do it properly with distilled water. However, the nuisance factor of driving 13 miles to leave my car there would be a pain. Then another pain to pick it up later.

I trust my cousin to do a good job because he cares and he will come to me. (I'm no longer able to drive, but still need my car for transportation. Others use my car to drive me places I need to go.)

Should I ask my cousin to use a chemical flush first, and then flush again with distilled water; or just flush twice with distilled water? I'm not aware of any clogs or other problems with the system. It currently functions properly.

I bought 2 gallons Peak Titanium concentrate, and 10 gallons of distilled water for flushing and refilling. If it doesn't all get used for my car, I'll give the remainder to my cousin.

For end result I want to have approx 50/50 mix of Peak Titanium and distilled water.

 

[billt460]

I'm willing to bet that whatever chlorine and other chemicals have long ago leached out of the coolant. Chlorine doesn't have a long life. It's why it constantly has to be added to swimming pools. But it would still be a good idea to have it drained and flushed with distilled water. I doubt it needs a chemical flush.

I'm in a similar situation with my 2015 Jeep Grand Cherokee. It still have the original factory coolant in it. But it only has 19,000 miles on it. I still want to have it drained and flushed.

Normally I do this stuff myself, but I'm not getting any younger, and I can't even see the drain plug. And from what I've read, unless done properly, the 5.7 HEMI V-8's are notorious for trapping air pockets in the cooling system that can lead to overheating issues. And I don't want to create a headache for myself.

 

[Lubener]

Unless there is rust present in the coolant or you are changing coolant types, a flush is not necessary. I would have refilled with a 50% Dexcool and distilled water solution.

 

[Carlostrece]

Unless there is rust present in the coolant or you are changing coolant types, a flush is not necessary. I would have refilled with a 50% Dexcool and distilled water solution.

I'm changing from Dexcool to an All-Vehicles/Universal coolant with no 2-EHA because that will be easier on my OEM plastic lower intake gasket and plastic coolant elbows. Also, it might provide better corrosion protection too.

So I think a flush would be a good idea (though not required).

What I'm asking is: Would 2 distilled water flushes be good enough, or should I do a chemical/additive/cleaner flush followed by a distilled water flush?

I already own 10 gallons of distilled water.

 

[nwjones18]

I’ll be honest I think you are overthinking it a bit… my dads 95 LeSabre has been on hose water and universal coolant it’s whole life and has had no coolant system issues beyond one water pump. If I was you and wanted distilled I’d have your cousin pull thermostat and do several drain/fills with distilled water only then add right amount of concentrated coolant of your choice..

We have many vehicles that are 30+ years old and have been in family for 20 years with us on tap water and universal coolant full of 2-eha and none have cooling issues beyond normal old car stuff youd expect.

 

[melk]

are you doing a passive (engine off) drain and fill or active (engine on) ?

remember there is coolant in the heater core and hoses and the only way to circulate that is with engine up to temp and the heat turned on.

in that case you would need to use the garden hose to ensure it is refilling as fast as it is getting drained out. once it is running clear you could use the distilled water

 

[johnmyster]

Man, just take it to a mechanic.

 

[Urshurak776]

How I do it last time in our Hyundai Santa Fe: Coolant capacity is 8.1 quarts.

Drain radiator. It is roughly half of the capacity in the Santa Fe. Add distilled water. Run engine for a few minutes with heat on high. Once warmed up, shut engine off.

Wait a few minutes (it's hot!)

Drain radiator. Do it again.

Keep doing this until the fluid being drained is crystal clear. When this happens. I do it one more time.

Drain radiator, refill with concentrate to half system capacity. Run engine (warm back up.) Shut down and check with one of those little dealies that tells you what temperature you coolant mix is good for.

Add 50/50 to over flow (you did drain overflow tank, right?)

Squeeze your hoses and check level every day for a few days, add as needed to make up for the air pockets that have dissipated.


My method isn't prefect, but it has worked fine for me. As long as you know capacity of your engine, not hard to do.

 

[Owen Lucas]

I don't think you to flush just because city water was used previously. it will probably take a long time for any adverse effects if any at all to be noticeable, and I mean, way beyond the lifespan of the vehicle, maybe another 199k. But if it makes you feel better, then go for it.

Here is a video for the Liqui Moly Radiator Flush that I completed a while ago. I rinsed the radiator once to get any residue out and used distilled water:

 

[Capt W]

Unless your water supply is heavily mineral-laden well water, there's nothing wrong with using municipal water for flushing/rinsing the cooling system. Don't know what you mean by "properly" flushing the system with distilled water. Whose definition of "proper" is that? The FSMs for all four of my vehicles states flushes should be done with plain water...not distilled, de-ionized, etc. The distilled water is largely an internet myth. If it makes you sleep better at night, then go for it. When you conduct a flush correctly, any minerals left behind will be nothing more than a trace. You only need distilled water to make your final 50/50 coolant mix.

That said, not one person thus far has mentioned pulling the block drain plugs to ensure 1) any settled sediment is flushed out, and 2) the cooling system is almost 100% empty to facilitate a complete 50/50 refill. All of my cars have at least one block plug, none of which are that difficult to remove. To the OP, the last 3800 I serviced (a 1990 Olds 88) had two plugs.

I flush my systems with a good old-fashioned garden hose and drain the system thoroughly. I flush heater cores separately by removing the hoses. When I'm done I use a makeshift rig of old heater hoses hooked to the "blow" function of my old shop-vac to gently blast excess water from the system. Then I button it all up and refill with the factory-specified quantity.

 

[Nukeman7]

I use the inexpensive Prestone flush adapter kit to ensure nearly all of the old coolant is removed. If you don't want to cut the heater hose, you can buy an extra hose clamp and a foot of appropriate diameter hose to install the kit temporarily to perform the flush.

My process is similar to the video below, but I also remove the thermostat before flushing and clean out the overflow bottle separately. I also follow-up the hose flush by draining the tap water/refill with distilled water/drive for a few miles/ let engine cool, then drain and refill with concentrated antifreeze at half the volumetric capacity of the cooling system. Finally, use distilled water to fill up the remaining capacity which will ensure the final concentration is 50/50%. Drive to operating temperature to burp trapped air and refill void space with distilled water. Don't forget to add a 50/50% mix to the overflow bottle.

 

[billt460]

Be careful using a flushing tee connected to a garden hose. Most automotive cooling systems are designed to operate between 13 and 16 PSI. Hose spigots operate at residential city pressure. Which is usually anywhere from 45 to 65 PSI.

If your radiator and / or your heater core is even partially clogged, the pressure can skyrocket. This can generate leaks. Especially with the newer plastic / aluminum radiators and heater cores.

 

[slacktide_bitog]

It's almost impossible to drain the coolant on a 3800 because you need to access the knock sensors. Perhaps you can remove them with this type of oxygen sensor socket. According to page 6-76, or 340, of the owner's manual, it holds 13 quarts! So see how much you can actually drain out, how close you can get to that 13 quart number.

The 3800 knock sensors use a 22mm or 7/8 size bolt with a wire connected to it, just like an oxygen sensor.

When it's time to refill, the Lisle coolant funnel is awesome. The Peak Titanium is also good stuff.

 

[Nukeman7]

Be careful using a flushing tee connected to a garden hose. Most automotive cooling systems are designed to operate between 13 and 16 PSI. Hose spigots operate at residential city pressure. Which is usually anywhere from 45 to 65 PSI.

If your radiator and / or your heater core is even partially clogged, the pressure can skyrocket. This can generate leaks. Especially with the newer plastic / aluminum radiators and heater cores.

If you take out the thermostat, open your temperature control valve to high heat, remove the radiator cap and/or disconnect the lower radiator hose, it will allow pathways to relieve back pressure should there be a full blockage. It is the higher municipal water pressure that creates the extra flow turbulence to help dislodge the build-up of deposits.

FWIW, I've never encountered any problems using this technique with all sorts of vehicles, including neglected $300 junkers. However, YMMV.

 

[Carlostrece]

Earlier, I had a misunderstanding when a Peak technician told me to "only use distilled water". I now realize he was referring to the last flush and the fill (along with concentrate) to arrive around 50/50.

Earlier, I thought he also meant distilled for all flushing.

I'll do 1st flush with tap water (likely a garden hose). Then 2nd flush with distilled water. I'll follow detailed flushing instructions provided in this thread.

Then drain radiator and fill with concentrate. Then drive with heater on. Then use coolant tester to check the mix and adjust as necessary to arrive at 50/50. I will also burp it and top off after each of the initial 2-4 drives.

 

[Carlostrece]

When I burp system and top it off, do I need to pour 50/50 into radiator, or just add it to the coolant overflow bottle?

 

[slacktide_bitog]

When I burp system and top it off, do I need to pour 50/50 into radiator, or just add it to the coolant overflow bottle?

Does your car even have a radiator cap? Most Deathcool-era GM cars have a pressurized coolant tank and no actual radiator cap

Is your overflow bottle pressurized? Do you actually have a radiator cap?

 

[Lubener]

I'm changing from Dexcool to an All-Vehicles/Universal coolant with no 2-EHA because that will be easier on my OEM plastic lower intake gasket and plastic coolant elbows. Also, it might provide better corrosion protection too.

So I think a flush would be a good idea (though not required).

What I'm asking is: Would 2 distilled water flushes be good enough, or should I do a chemical/additive/cleaner flush followed by a distilled water flush?

I already own 10 gallons of distilled water.

If you feel the Dexcool is at fault , wouldn't you think after all these years the damage has already begun?

Personally, from what I saw, the gaskets and elbows were junk from day one along with the design of the upper manifold . Once those are changed out, that 3.8 is a fine engine capable of going the distance.

 

[Carlostrece]

If you feel the Dexcool is at fault , wouldn't you think after all these years the damage has already begun?

Personally, from what I saw, the gaskets and elbows were junk from day one along with the design of the upper manifold . Once those are changed out, that 3.8 is a fine engine capable of going the distance.

I will probably change the gasket and elbows eventually, but I can't deal with that now. For now I just want to flush and replace coolant with good non 2-EHA coolant.

 

[Carlostrece]

Does your car even have a radiator cap? Most Deathcool-era GM cars have a pressurized coolant tank and no actual radiator cap

Is your overflow bottle pressurized? Do you actually have a radiator cap?

My car's radiator has a metal radiator cap.

A small diameter black hose connects radiator to the over flow jug.

I don't think the plastic overflow jug is pressurized. It has a cheap plastic cap.