How does one flush the coolent system properly?

I posed the same ques. on the "Are Dino owners all dead" thread; The only reason I want to do it is the presence of what look like very fine metallic flakes appearing like aluminum, prob only a few microns in size, in my coolant (original coolant after the engine rebuild soon after I got the car in 2001-02). The only way I knew about this at all was a year or two back when I had to empty the overflow tank to allow a resolder of same to correct a leak. The coolant appeared somewhat cloudy, and the stuff gradually settled out of solution when allowed to stand. Don't really know if this is pathologic or not. My "wrench" buddy, who did most of the rebuild, does not seem too concerned, but I'd still like to flush if it's not too difficult. I assume this is fine debris related to the rebuild; note the water pump was replaced then also, and the engine runs very cool; only about 1500 -2000mi on the "new" engine.

 

I believe I have answered my own question. Further consultation with my "wrench" buddy referred to above, yields the following recommended method:
1. With car raised, preferably on a lift, and with a COOL engine, disconnect the main coolant hose under the car, near the firewall, and drain old coolant. Do not/need not attempt any drainage at the radiator.
2. Reconnect coolant hose.
3. Refill system with water only (no flush chemicals generally needed).
4. Run engine for a short time to circulate any remaining crud in the old coolant.
5. Immediately and carefully redrain system as before.
6. Reconnect and refill with your favorite coolant mixture. My friend prefers standard Prestone or other ethylene gylcol- based products, rather than the orange/expensive specialized coolants now used in many modern cars, eg MBZ's and Audis.

Sounds simple enough; I'll try this method as my own test case in the next few weeks, and report back.

 

Hmmm, makes sense. Here's the way I've typically done it.

1) Put car on lift and make sure lift pads at front are slightly more elevated than rear lift pads so that the radiator drains out
2) Open bleed screw by the radiator
3) Disconnect the main coolant hose under the car and drain old coolant - ensure you have your mouth closed and are wearing old clothes
4) Clean up all of the fluid which spilled on the floor or splashed on the walls as it fell from great heights and hit the poorly designed coolant receptacle
5) Shower to get the coolent out of your hair and pores which covered you when the ridgid coolent tube final came lose from the hose
6) Open the taps on the front and back of the engine to drain the block of coolant
7) Use 1 box of shop towels to soak up all of the coolant which spilled onto the gearbox case when you opened the engine drains
8) Shower again to remove coolent which covered you when the engine drains were opened and dripped from multiple locations
9) Bandage hands to ensure cuts and scrapes received while trying to dry the gearbox case don't get infected
10) Close the engine drain plugs and radiator bleed screw
11) Refil radiator by pouring distilled water and coolant into expansion tank
12) Run car and bleed radiator to ensure no vapor lock occurs

Now you know why I hate changing the coolant in the Dino. In the future I'll pass on opening the engine block drains and just bleed twice as Robert suggested. That being said, I'm sure I'll get covered in coolant and take a few years off my life.

Cheers...Keith

 

Keith- Truly a tragicomic tale by someone who's been there, done that! One probably naive question, where exactly is the "bleed screw by the radiator"? A picture of this would be wonderful if not too much trouble. Thanks, Bob

 

Also important to burp the hose at the top of the water pump. It's a spot where it is easy to trap air, and that will reduce the flow to the engine.

Doesn't the Radiator have a stopcock (petcock?) on it? I'm pretty sure there's one on the top and the bottom, probably there for a reason, right?

DM

 

Actually, the radiator bleed screw is "on" the radiator. It's located 'stage right,' near the aft-side corner of the top tank. It's a small knurled knob. I don't have any pics, but you can find 'em, along with a slew of tips, if you look for "bleed screw" in the Search mode, above.

'just a reminder...many parts, systems, procedures & techniques are common to the 206/246 and the 308. I find a lot of good stuff in the 308/328/Mondial section, too.

Good Luck,
Coop

 

My approach is to change the coolant every 2 yrs or so, so it never goes really bad. Therefore you don't really need to replace ALL of it each time.

The goal is to minimize air entry into the system, especially into the main tubes below the car between engine and rad.

1) park car in driveway, with front wheels in gutter and rear on sidewalk.
2) place long, thin child's snow sled under radiator area to catch coolant--it is very poisonous to pets and other animals
3) remove cap from surge tank
4) open bleed screw on upper R portion of radiator
5) working from above, open drain valve at bottom of radiator on L side-- actually mine usually just comes out completely. Have hose ready to immediately wash away coolant from surfaces as it comes out. Also, protect fenders and have wet rags handy in case some coolant gets on paintwork.
6) when no more coolant comes out, close drain valve
7) have someone pour coolant into surge tank until no more air or bubbles come out of bleed screw, then close it
8) fill surge tank maybe half full
9) start engine. as it warms up, open bleed screw intermittently to release air that has appeared there. Also keep checking surge tank level, adding as necessary. When engine is hot and no more air comes out of bleed screw, you are done. Take car for a drive to dry off the wet surfaces in the radiator area.
10) park car in garage and when engine is cold, check surge tank level and add if needed.

This has worked for my Dino and similarly built Pantera for the last 20 years.

Jim

 

Jim:

I've got a few questions/comments regarding your suggested method for changing out the coolant on the Dino.

1) Nice call on using the drain valve. Can you reach in and move that valve with your hand or did you build some sort of tool to grasp it from up top? I didn't know that drain valve was accessible but with the "Sled" method, perhaps it's worth trying again because the coolant won't drip all over the inside of the car's nose if/when I get it open. Perhaps I'll build a low pan with edges that directs everthing into a fitting which I can run a hose into. Hmmm.

2) Do you direct all of that coolant which lands on the sled into some receptacle or do you just wash it into the storm drain? I'm sure I commit my share of environmental sins but if your answer to this last question is the latter, that's a big no-no. In many places (Seattle for sure), the storm drains don't run into sewers and get treated, they run out streams and ultimately into our local bodies of water. So washing antifreeze into a storm drain may protect dogs and cats but it kills marine life and the ecosystem. Up this way, we have to collect antifreeze and take it to an EPA collection site.

3) Do you have a fiberglass floor panel on the underside of your car which is close to the nose and which must be removed in order to slide the sled into place?

4) Why a sled?