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Coolant flushing

Dakar Timm

Dakar Timm

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Location
Lake Mills Wisconsin
I'm about to flush the coolant out of the '66 Polyhead . A very long time ago , late '70's was the last time I remember doing something like this .
I cut the heater hose coming from the thermostat ,going into the firewall . Is this still where we cut to install the "T" ?
 
I used to do it that way, but for maintenance level flushing the way I have been doing it for a long time is:

Drain the coolant from the radiator, refill with water, run the car up to op temp with the rad cap off, open the radiator petcock again, stick a hose into the radiator and balance the in/out flow letting the car run until discharge water out of the petcock is clear.

Drain radiator and refill with 100% antifreeze. This should leave you with close to a 50/50 anti-freeze water mix. You might adjust for your climate. No cut hoses, no new gaskets, nothing taken apart, etc.
 
If you are wanting to do this at home.
This is the stuff. Jegs, Summit & some auto parts stores carry it.
It's aprox $ 20 per qt. You will need 2qts each time to do a good job.
Drain old coolant, do a quick flush with your hose. Pull the thermostat. Replace thermostat housing , dump your 1st 2 qt. In fill with water and drive the car for a few days, several heat cycles.
When it's cool pull the bottom hose and top hose off the radiator dump into a pan or gravel, not you concrete. You will be surprised at the amount of rusty crap that will run out.
Garden hose flush rad and engine 3 or 4 times with block drain plugs out.
Once water runs clear, put it all back together , add 2 qt of flush top off with water and drive again for a few heat cycles. Repeat flush again till clear.

Your block is now full of water so add 1 gal of pure antifreeze if you live in a cold weather state. Finish with 50/50 antifreeze,water mix.

399-tc001.jpg
 
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I second Therm-O-Cure.

It's the only ting that finally cleaned out my Dakota.

Also, it's difficult for the thermostat to open if the water in the radiator is flowing through, and constantly being replaced with cooler water.

I do use the T and I periodically shut off the water hose and loosely put the cap back on, then watch the temp gauge.

When it gets close to normal, I carefully pull the cap and turn to hose back on.

If you time it right, pressure hasn't had a chance to build.
 
I prefer draining old coolant, put in bottle of flush and distilled water, drive 2 days and make sure the thermostat opens up at least once, drain water/flush, fill with distilled water, drive until thermostat opens at least once, drain water, fill with 50/50
 
I have a similar issue and need to drain / flush. I am in the process of restoration and before I purchased the car (69Bee, 383) the engine was rebuilt. I had noticed that the water is very rusty and this was concerning, however during the restoration and pulling the Heat/AC box I realized the source of rust was the heater core. It was in terrible shape. My concern now is getting the engine and radiator properly flushed before I install the new box with heater core. This thread helps, and if anyone wants to weigh in with additional info / procedures it would be much appreciated.
 
dspur said:
I have a similar issue and need to drain / flush. I am in the process of restoration and before I purchased the car (69Bee, 383) the engine was rebuilt. I had noticed that the water is very rusty and this was concerning, however during the restoration and pulling the Heat/AC box I realized the source of rust was the heater core. It was in terrible shape. My concern now is getting the engine and radiator properly flushed before I install the new box with heater core. This thread helps, and if anyone wants to weigh in with additional info / procedures it would be much appreciated.
Click to expand...
If it was mine, I would take the rad and heater core to a rad shop and get them tested and cleaned.
Someone on here must have solid advice on flushing the block.
Have a friend who made his car really nice. Another buddy asked if he was going to check the heater core, said it should be okay. About 100 miles into a 300 mile trip to a car show, the heater core sprung a leak. Did a by-pass on the side of the road. Sure made a mess of his carpet and underlay.
 
Last edited:
440 4 speed said:
If it was mine, I would take the rad and heater core to a rad shop and get them tested and cleaned.
Someone on here must have solid advice on flushing the block.
Have a friend who made his car really nice. Another buddy asked if he was going to check the heater core, said it should be okay. About 100 miles into a 300 mile trip to a car show, the heater core sprung a leak. Did a by-pass on the side of the road. Sure made a mess of his carpet and underlay.
Click to expand...
The heater core was replaced but not yet installed. I do agree that I should take the radiator to a shop. Now about the block…. lol
 
Are you referring to the "Prestone" reverse-flush kit ? With the yellow plastic T-fitting ? We used to do installs of these every now and then during a coolant system service.
 
Last edited:
Dakar Timm said:
I'm about to flush the coolant out of the '66 Polyhead . A very long time ago , late '70's was the last time I remember doing something like this .
I cut the heater hose coming from the thermostat ,going into the firewall . Is this still where we cut to install the "T" ?
Click to expand...
You install the T in the hose from the engine into the heater core inlet.
 
I wish someone made an aluminum exit drain like the plastic one that comes in that kit.
After about 3 uses it doesn't fit tight anymore.
Also- I've added a good quality (red, flexible) garden hose washer to the T cap.
The way it comes eventually leaks.
 
If the block is full of crud, it's all built up around the rear cylinders. If you could punch out the rear plugs and pressure wash in there, that would be ideal. Even prod around with a wire hanger
 
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