Write-Up: Flushing Radiator Coolant

Jack the R wrote:

Here's hoping. That wouldn't normally be the case though, would it?

I checked mine after a week with a new radiator, no air in system.

I don't really understand the fear of air in the coolant. There should be two undesirable effects if you have bubbles in the system: 1) overheating, and 2) a gurgling sound in the heater core (dash). If you aren't experiencing either issue, don't assume you have a problem.

Maybe I'm oversimplifying here, but when the system is cold, air bubbles should rise to the top of the radiator. If you take off the cap and top off the coolant, the air should be evacuated. With engine running, you can actually see the bubbles reaching the surface.

When I swapped my coolant with water earlier this year, I drained the antifreeze from the radiator several times, each time replacing with distilled water. After about 6 gallons, the color of the coolant became almost clear. I mixed in a couple bottles of Water Wetter at the end. I have had no gurgling or cooling issues since, and never cracked open the bleeder. I think the air escaped through the radiator cap when I was filling.

I do have a small leak in my radiator, near the top hose. Over time, the level drops, and one time I let it go too low. The engine did not even get hot, but I noticed the gurgling sound in the dash, signalling air was introduced into the system. I topped off the system (about 1/2 gallon water) and the gurgling subsided. Again, I did not use the bleeder near the thermostat. No problems since, except I put about a gallon of water (80¢) in the coolant reservoir each month.

As I said earlier in the thread, it's one of the easiest systems to bleed. It almost bleeds itself. Stop worrying!!!!

I believe earlier in the thread we were talking about the possibility of air and dexcool combining to eat gaskets. That's my only worry, but I agree that the way I happened to fill the radiator, topping it off over days, gave all the air time to work out of the system.

I don't think the gasket problem should be blamed on dexcool, or air in the system. It's a poor quality gasket choice, and it's going to eat through, given enough time. I think a lot of cars are running fine with small gasket leaks and the owners aren't even aware of it. To be sure, replace the gasket, or if you aren't seeing any problems, see how far you can get on the OEM.

First time I've heard that. Do you think the decay comes from time or mileage?

I'd guess a little of both. If they'd used the right gasket, everyone would be in love with Dexcool. It really is amazing how long the stuff lasts. Other than the small leak I have in the radiator, my cooling system still works great after 13 years, and the coolant was very clean last time I drained it.

Antifreeze when fresh has a PH that is alkaline. Over time, the PH decreases, and eventually goes acidic. I've seen old anti freeze eat through the metal intake manifold bath tub type gaskets. If you run a car with Dexcool in it, low on coolant, it forms a sludge or gel that can damage things. I've been using the Green stuff, and changing it every 2 years. I feel better about that.

Maybe you're right, Larry. I personally haven't had a problem with the Dexcool, but if you're running at a low level, and there's a lot of air in there, I can't believe that's a good thing. It's hard to say if a few small bubbles circulating in an otherwise full system would have any ill effects. So far I've used Dexcool for the life of the car, changed once about 6 years ago, now about to replace the radiator and replace with new coolant, due to a small leak near the top.

AA wrote:

Maybe you're right, Larry. I personally haven't had a problem with the Dexcool, but if you're running at a low level, and there's a lot of air in there, I can't believe that's a good thing. It's hard to say if a few small bubbles circulating in an otherwise full system would have any ill effects. So far I've used Dexcool for the life of the car, changed once about 6 years ago, now about to replace the radiator and replace with new coolant, due to a small leak near the top.

No, I'm talking about running the system really low on coolant, and leaving it that way for a long while. I've seen people completely ignore basic maintenance on a car. I check all my fluids on a regular basis. Some people will drive a car even when they know something is wrong. I was just reading a post by someone on another car board. He was asking about his car's transmission, . The trans was slipping badly, and he related that he had bought the car recently, and the previous owner had replaced the transmission. The car had a bad ATF leak, which apparently, he couldn't fix himself, so he took it in to a garage. They tightened a clamp, and sent him on his way. He says he asked if they had checked the fluid level, and they said they had. He continued to drive the car, even though he felt it slipping badly. He finally added 3 1/2 quarts of fluid, but it continued to slip, and now he has shifting problems. Now he wants to try and fix it, but I think it is probably too late, and I told him so. Someone I know at work, drove a car that was running hot for some time. He finally asked me to look at it, and with the car running fully warmed up, I could feel the upper part of the radiator was cool to the touch. The level was halfway down the radiator, and the Dexcool remaining was a brown nasty looking muck. That engine didn't last much longer.

LARRY70GS wrote:

AA wrote:

Maybe you're right, Larry. I personally haven't had a problem with the Dexcool, but if you're running at a low level, and there's a lot of air in there, I can't believe that's a good thing. It's hard to say if a few small bubbles circulating in an otherwise full system would have any ill effects. So far I've used Dexcool for the life of the car, changed once about 6 years ago, now about to replace the radiator and replace with new coolant, due to a small leak near the top.

No, I'm talking about running the system really low on coolant, and leaving it that way for a long while. I've seen people completely ignore basic maintenance on a car. I check all my fluids on a regular basis. Some people will drive a car even when they know something is wrong. I was just reading a post by someone on another car board. He was asking about his car's transmission, . The trans was slipping badly, and he related that he had bought the car recently, and the previous owner had replaced the transmission. The car had a bad ATF leak, which apparently, he couldn't fix himself, so he took it in to a garage. They tightened a clamp, and sent him on his way. He says he asked if they had checked the fluid level, and they said they had. He continued to drive the car, even though he felt it slipping badly. He finally added 3 1/2 quarts of fluid, but it continued to slip, and now he has shifting problems. Now he wants to try and fix it, but I think it is probably too late, and I told him so. Someone I know at work, drove a car that was running hot for some time. He finally asked me to look at it, and with the car running fully warmed up, I could feel the upper part of the radiator was cool to the touch. The level was halfway down the radiator, and the Dexcool remaining was a brown nasty looking muck. That engine didn't last much longer.

I suspect that some of the problems posted on this board are, from time to time, by folks who did not know to or did not care to keep after maintenance. I also have learned that some things that turn out to be maintenance items on high mileage cars (mine is now over 250 K mi) are not on the maintenance schedule at all. Like the supercharger coupler. Thirdly, there are some things that kinda defy fixing. One that comes to mind are the click-fittings on late model Ford transmissions. Another is the bushings in our front control arms. A fourth problem is mechanics who, although trained, can not or do not do the work correctly. For instance if you have a mid '90s Lincoln Continental, before you do a 4-wheel alignment you really must check and reset the ride height using the factory scan tool. This is lost on some of the current crop of Ford mechanics. On our cars, an analogue is centering the steering rack and wheel when you do an alignment. If you don't do it right, the Magnasteer tends to pull the car off course to what it thinks is the center *when at speed.* So the tech doing a low speed road check will never find the issue.

Albertj

Does anybody know where is the engine block coolant drain plug if any??? winter is coming here and looks like my cooling system is nasty with almost 0 antifreeze pure water!

Example:


Are the knock Sensors the "Engine Block Drain Plugs" on the 3800 engine?

You can remove the knock sensors to remove the coolant. But why don't you just drain what is in there from the radiator and add new coolant. Once you start the engine, the coolant will go through the engine and mix in with the new coolant. The little bit in the engine won't make a difference. You won't be able to remove all of the coolant anyway. There is some in the heater core and related hoses. If the coolant is that bad, you can always change it again or run some water through the system to flush out some of the junk. You can then add the new coolant.

Yeah, I just decied to just flush the entire system with the thermostat removed and with the garden hose on the inlet hose of the radiator, start the car and wait until clear water comes out

Glad I read through these. Flushed the radiator out today. Only issues I had were the clips breaking removing the plastic shroud, and getting the proper replacements. Although it was a second trip    to parts store (which I hate) finally found better ones that screwed in. Was also wondering if anyone has cut an access port in the shroud to get to the drain plug eliminating the need to remove the shroud itself ? Possibly add a threaded extension to the drain plug to avoid spillage on inside of shroud. Also replaced the cap with a vented cap that looks nice and works well.

AA wrote:

The radiator replacement I have planned should be a lot of fun. I'm just going to cut both hoses, rip the unit out, and replace all.

Now that a million years has passed I'm wondering why no one mentioned hose picks?

Jack the R wrote:

AA wrote:

The radiator replacement I have planned should be a lot of fun. I'm just going to cut both hoses, rip the unit out, and replace all.

Now that a million years has passed I'm wondering why no one mentioned hose picks?  

Don't consistently need them, except maybe if you're replacing the hoses to/from the heater core. They are stuck-o.

That's what I'm talking about though, the heater core hoses.  Mine are 22 years old now.  We talked about those hoses but no one mentioned a pick. I didn't know such a thing existed until a video about hose picks randomly popped up on YouTube. I had bought the hoses but ended up not changing them for fear of damaging the heater core, I suppose they are dry rotted now. What a waste!

Jack the R wrote:

That's what I'm talking about though, the heater core hoses.  Mine are 22 years old now.  We talked about those hoses but no one mentioned a pick.  I didn't know such a thing existed until a video about hose picks randomly popped up on YouTube.  I had bought the hoses but ended up not changing them for fear of damaging the heater core, I suppose they are dry rotted now.  What a waste!  

They are probably not dry rotted. *If* I remember the story right, a bit before our cars were built there was a significant change in chemistry for making the hoses - I think, something like they have been EPDM (ethylene propylene diene monomer) now for decades. EPDM is a family of synthetic rubber chemistries. Rubber roofs, gaskets, all kinds of stuff is made from EPDM. The hoses that have been made since the '90s y *just* don't fail as soon or as frequently as they did when we were kids/teens.

The tech at my local Buick dealer, who changed my hoses I guess about 10 years ago, I think he said he used a box knife to slit them, then peeled them off and cleaned the nipples, then installed the new hoses. He said it wasn't a bad idea to change them on a 190 thousand mile car but the old ones were still OK. Said he hesitated because they are such a pain but he did them (a) because I asked and (b) he saw that I replaced and dated (wilt a silver Sharpie) **everything else** in the cooling system so changing them was not really that big a deal and got rid of the last failure point.

IIRC the hoses are 2 layers of EPDM; the inner is for chemical resistance, there is a cord tube primarily for burst strength, and an outer layer for weather/oil resistance. Again, I think you'll find they're OK. To amuse yourself, wet a rag with silicone spray or rubber preservative and wipe them off next time you're under the hood.

Mine are original and look just fine. They definitely ARE NOT dry rotted. I bought replacements from Rockauto years ago. I have no plans to touch them unless they start loooking bad.

...like I said, "To amuse yourself, wet a rag with silicone spray or rubber preservative and wipe them off next time you're under the hood."

Given what had happened with EPDM chemistry in the 90s, I doubt there is an issue. BTW they use a formulation of EPDM in serpentine belts too.  I have 100,000+ miles on a set of Goodyear Gatorbacks and upon inspection can not find an excuse to replace them.

albertj wrote:

...like I said, "To amuse yourself, wet a rag with silicone spray or rubber preservative and wipe them off next time you're under the hood."

Given what had happened with EPDM chemistry in the 90s, I doubt there is an issue. BTW they use a formulation of EPDM in serpentine belts too.  I have 100,000+ miles on a set of Goodyear Gatorbacks and upon inspection can not find an excuse to replace them.

I know what you mean. I just recently replaced my belts just because they were on the car since I bought it in 2004. They looked fine.

LARRY70GS wrote:

albertj wrote:

...like I said, "To amuse yourself, wet a rag with silicone spray or rubber preservative and wipe them off next time you're under the hood."

Given what had happened with EPDM chemistry in the 90s, I doubt there is an issue. BTW they use a formulation of EPDM in serpentine belts too.  I have 100,000+ miles on a set of Goodyear Gatorbacks and upon inspection can not find an excuse to replace them.

I know what you mean.  I just recently replaced my belts just because they were on the car since I bought it in 2004.  They looked fine.

Gates changed its guidance to state to replace the belt when the face wears down by so-so much. They avoid mentioning risk (or even likelihood) of breakage. Thinking about it, I'm not sure belt breakage is so much of a "thing" anymore.

In some cars I imagine some of the old-chemistry belts might be in use, maybe they bought a NOS belt from a car parts store in the Twilight Zone (Rod Serling was born and lived near here, see https://en.wikipedia.org/wiki/Rod_Serling) or just never got around o changing the older belt... point is the newer EPDM belts wear very differently than belts made with the older chemistry did.

Albertj

rk0ehn wrote:

Does anybody know where is the engine block coolant drain plug if any??? winter is coming here and looks like my cooling system is nasty with almost 0 antifreeze pure water!  

Example:


Are the knock Sensors the "Engine Block Drain Plugs" on the 3800 engine?

Remove the clamp that holds your lower radiator hose to the radiator or to the water pump, then pull that end of the hose, watch out as most of the coolant from the engine will come out.

After that, reinstall the hose, remove the thermostat, leave seal in housing and reinstall the gooseneck without the thermostat and run your garden hose into the radiator fill opening with the petcock open, run the engine while filling the radiator with your garden hose on until everything that comes out of the petcock is fresh clean water. You can then shut engine off, let some water drain from the radiator and close petcock. Install some Prestone engine coolant cleaner or whatever it's called and run that in with the clean water and your thermostat still removed for the recommended time.
Your engine temp will stay cooler than normal with thermostat out and cold water from your garden hose in the engine.

Once flushed per instructions on Prestone cleaning product drain radiator by opening petcock, remove the thermostat gooseneck and remove the lower radiator hose one more time to drain all water and flushing solution out.

When system is empty of water, put lower radiator hose back on, tighten petcock, replace thermostat and put in new seal and fill the system with a 50/50 mixture of anti-freeze and distilled water or buy the anti-freeze premixed. Shouldn't take much more than a gallon.

OH, I forgot to mention. I always pull the plastic overflow tank, easy to do, and flush and clean that out separately if it is discolored from dirty anti-freeze. Then naturally re-install. Replace that hose or any hoses that appear to be dry rotted or ready to crack and cause problems down the road.

If you put Green anti-freeze in, which I always did after having changed intake manifold gaskets, then do everything again every 2 years.

...also, if you don't use pre-mix coolant (I don't) then use distilled water, or condensate from a dehumidifier, to make up the water in your antifreeze mix.  Do not use municipal tap water.  I use condensate.

Finally - the "dirt" in the overflow bottle is sealant.  GM standard was to use 'bar's leaks' sealant tabs (made of ground ginger and pulverized walnut shells I kid you not) to deal with certain issues inherent to the 3800.  When your Riv was built those tabs went in at the factory.  When you flush-fill coolant it's a really good idea to add those tabs, 2-3 of them, to the coolant at the radiator cap (NOT the overflow bottle).  GM says you don't have to add the tabs anymore, but the tabs have a bit of rust/scale inhibitor and tend to neutralize the pH of the coolant. So you'd *want* to use them with the coolant anyway, especially the OAT DexCool.