Prestone Radiator Flush

[Tools R Us]

Have used it several times:

... Not magic in a bottle but cleaned some and did no harm. ...

Agree, pretty weak, but does some, don't expect miracles.

... Deposits do not always end up getting flushed out and sometimes cause harm.
...

Any deposits in the system can break loose at anytime. If the system is dirty, I prefer to make the attempt at flushing as much as possible out.

When doing this we; flush the system with a garden hose in through the heater valve and out the cap, until it runs clean. Then put in the flush chemistry, drive, allow to fully cool and repeat the same hose flush. Some always comes out on the second flush, but nothing like the first time. We only use it when the system is really dirty.

 

[Kaninja]

When doing this we; flush the system with a garden hose in through the heater valve and out the cap, until it runs clean. Then put in the flush chemistry, drive, allow to fully cool and repeat the same hose flush. Some always comes out on the second flush, but nothing like the first time. We only use it when the system is really dirty.

Really dirty!

I flush the system differently and it may not be as good as flushing through the heater hose and out the cap. Making sure heater is on full hot before I shut off engine, I remove thermostat and just use my garden hose through the top of rad. Holding the thermostat housing in place by hand I repeatedly fill the system and when I feel pressure wanting to push housing off of block I pull t-stat housing away letting it drain while still holding garden hose full blast in top of rad. Repeat a bunch until it runs clear. Slap thermostat back in tighten the 3 bolts and done.

 

[SaturnAscends]

What's the consensus on using this stuff nowadays? I was going to add it to some distilled water to avoid having to do more than 1 DW flush. But will it do more harm than good on an old system?

 

[BILT4ME]

What's the consensus on using this stuff nowadays? I was going to add it to some distilled water to avoid having to do more than 1 DW flush. But will it do more harm than good on an old system?
View attachment 2971431

Did you even read the entire thread?

 

[gummycarbs]

I was going to add it to some distilled water to avoid having to do more than 1 DW flush

You have to do at least one complete water flush after using the chemical. Plan on several.

Personally, I flush out the chemical product with tap water. I run tap water through the radiator, the block, and through the heater cores. That's with the hoses pulled. You want to get all the debris out. Then I finish with a distilled water flush and then back to coolant.

I did this back in 2017 because I didn't know the vehicle's history. I also replaced the water pump, since it's fairly common for the debris to damage water pump seals. No issues since.

If your system is significantly corroded and you're not planning to replace your water pump, you might want to put an inline filter in a radiator hose.

Earlier, I flushed an old, overheating Jeep engine. I probably did three or four chemical flushes, running several days for each one. I kept going until tap water flushing came out clear.

But will it do more harm than good on an old system?

Only if your system is barely hanging on by a layer of corrosion.

If you're not having any cooling issues and you don't have reason to believe that your coolant passages, radiator, or heater cores are blocked or corroded, there's no reason to use a chemical flush.

 

[SaturnAscends]

Did you even read the entire thread?

Yea but it seemed to be talking about an older radiator flush product.

Anyway @gummycarbs I’ll probably do a few flushes of distilled and only use the chemical if there seems to be a lot of corrosion and gunk in the system.

PO replaced radiator a few years ago and I haven’t noticed any issues with the cooling system, so hopefully it’s not too bad. Just wanted to switch from the orange stuff in there now to Prestone green.

 

[BILT4ME]

Yea but it seemed to be talking about an older radiator flush product.

Anyway @gummycarbs I’ll probably do a few flushes of distilled and only use the chemical if there seems to be a lot of corrosion and gunk in the system.

PO replaced radiator a few years ago and I haven’t noticed any issues with the cooling system, so hopefully it’s not too bad. Just wanted to switch from the orange stuff in there now to Prestone green.

From my many years of experience with old and unmaintained cars and trucks, if you try to flush to the point of it being perfectly clean, you will wash out all the gunk that is keeping it from leaking.

So, be prepared if you choose to flush with this (or any other product) that you may do more damage than good.

I see this with fuel and oil additives as well. It breaks loose crap that you don't WANT to break loose because it's keeping the holes from leaking and it can knock loose stuff that then causes damage internally. (carburetors, injectors, oil galleys, lifter valleys, heads)

I have a Studebaker that the oil, grease, and dirt that had caked on the outside of the engine was actually KEEPING the freeze plugs from leaking. The freeze plugs had already rusted through (from the inside) but the oil and grease was so caked on the outside that it held the pressure of the cooling system for thousands of miles!

I pulled the engine because of what I suspected and to replace the freeze plugs, and confirmed it was true. I also cleaned out about a quart of casting sand from when the block was cast in 1963.

 

[SaturnAscends]

From my many years of experience with old and unmaintained cars and trucks, if you try to flush to the point of it being perfectly clean, you will wash out all the gunk that is keeping it from leaking.

So, be prepared if you choose to flush with this (or any other product) that you may do more damage than good.

I see this with fuel and oil additives as well. It breaks loose crap that you don't WANT to break loose because it's keeping the holes from leaking and it can knock loose stuff that then causes damage internally. (carburetors, injectors, oil galleys, lifter valleys, heads)

I have a Studebaker that the oil, grease, and dirt that had caked on the outside of the engine was actually KEEPING the freeze plugs from leaking. The freeze plugs had already rusted through (from the inside) but the oil and grease was so caked on the outside that it held the pressure of the cooling system for thousands of miles!

I pulled the engine because of what I suspected and to replace the freeze plugs, and confirmed it was true. I also cleaned out about a quart of casting sand from when the block was cast in 1963.

Yea I have a spare AISIN water pump and have replaced most of my hoses, HCV, etc., but my biggest concern would be springing a leak in the heater core. I guess I'l just return that chemical flush and just stick to DW.

The hardest part is getting around to actually doing it; I've been putting this off for months lol. I wanna get it done before the summer heat though.

 

[BILT4ME]

Yea I have a spare AISIN water pump and have replaced most of my hoses, HCV, etc., but my biggest concern would be springing a leak in the heater core. I guess I'l just return that chemical flush and just stick to DW.

The hardest part is getting around to actually doing it; I've been putting this off for months lol. I wanna get it done before the summer heat though.

My concern about the heater core is my #1 about why NOT to use that stuff. I would rather replace a head gasket than replace a front heater core on one of these.

I just did my system, and I seriously considered using a cleaning product, then I found my sanity again, and I did 5 DW flushes. I was going to do more, but the temps were supposed to drop below freezing, so I stopped flushing and filled it with coolant.

Good luck, keep it simple.