How Many Flushes...

I’m flushing the coolant system in my 1996 B4. I pulled out the thermostat to make draining easier and emptied and refilled the system with tap water, using the lower radiator hose to drain it a couple times. Then I poured in a bottle of Prestone Flush/Cleaner and ran it for a few hours. Then I drained the system with the lower radiator hose again and refilled with distilled water. I’ve now drained and refilled with distilled water four times in this manner. Each time about five liters of clear water came out. The system holds 6.5 liters. Do y’all think four flushes with distilled water would be enough to get the Prestone Flush/Cleaner out before the final refill with 60% G13 antifreeze / 40% distilled water?

Is you heater on?

I think that would depend on what happens if the Prestone gets mixed with G13. If it solidifies or gels up, the only way I could see would be to blow out the lines with an air compressor.

h.ubk

I think four flushes would be fine. In this case you don't have to worry about the heater being turned on since coolant flow through the core occurs all the time.

The only time you need to make sure the heater is turned on completely is with a system where you have a valve in the hose to the core, these cars don't have that. The only reason they mention it in the Bentley is so when you refill the system you can tell when you have heat and that would be a sign the system is functioning properly.

I would think that if there is anything left in there it's so diluted it wouldn't be problem.

I haven't used a flush agent in years but if I did I likely wouldn't flush that many times.

Steve

When flushing my 6.0 Ford from the Ford coolant to Rotella ULLC, & using Fleetgard Restore as the cleaner, I was 7 flushes with distilled water. Assuming you are going from G11 to G13, I suspect you are Ok with 4 flushes. Anything other than a G11 in there, I would up it to 7.

Yes, heater on set to hot.

Ok, I’ll drain and refill it with distilled water a few more times then. It’s only 88¢ a gallon.

i just disconnect the top rad hose on most cars, still garden hose in rad cap and flush while running for a while...for this car I just stick it in the upper rad hose neck...if you keep flow low the t-stat should open enough to maintain a constant flush...pretty sure that will flush anything out...

I wanted to do the garden hose backflush through a T-connector in a heater hose, but I read on one of the forums here that it is not possible on our cars. But I could never find a reason why not. Have any of y’all heard that or know why we can’t backflush that way?

drain, fill, drive till to temp 3 times with distilled water. If its really bad i.e. brown or other crap in the coolant, you can add a small amount of vinegar on your first drain and fill. You can use Iron Out, works well and less damaging then vinegar, other methods are to use LAUNDRY detergent added. if you do add something on the first flush, do 2 more flushes with distilled. then flush with proper coolant. there are many heated debates on what to use and why but the reality is that if the engine and components were flushed properly, that any of the (works for this engine) type coolants is fine. I personally like to stick to OEM rated brands but on some cars that have coolant issues from time to time i use a cheaper substitute as i am changing thermostats or pumps or other parts more often and want to save a few bucks.

Here watch this.
https://www.youtube.com/watch?v=s--5ft5YiHg

Ok, I have now flushed it out with distilled water eight times.

Replaced the thermostat.

Refilled with g13 and distilled water for a 50/50 mix in the system.

Now I have no heat coming from the heater vents when I’ve had great heat all along with distilled water only. What would cause this now? One of the heater hoses going into the core is hot and the other one is cool. The heater is set to high as it has been throughout all eight distilled water flushes.

False alarm. Was just air in the system sitting up inside the heater core I guess. Once I drove it on the highway a mile or so, the heater started working again. Guess the water pump doesn’t have enough oomph to push through the heater core at idle when there is air in the system.

Glad it was an easy fix.

Did that video help? i learned to flush the heater core with fresh mix after watching it. The block and core and hoses and rad completely dry take the speck 6.5 Liters but ive never been able to add more than about 4.5 maybe 5 tops. This means that you have about 40% g13 mixed in. i always add a bit more. the trick i do is to add 1L of g13 then water so that on the last fill your supposed to add water but i top it off with g13 instead. Reality is that unless your in northern areas that get -30F or lower, 30% mix would actually suffice in -20F areas so your good. Just food for thought.
Also once you start up the engine a bit of air gets trapped in air bubbles if you didnt burp it good enough and will trap in the heatercore. once you let it settle for am hour and start it back up it fixes its self.
Glad to hear your success.

When you ever have to do work to your system again, use a clean 3 gallon shopvac to suck up the fluid as it comes out of the hoses, then filter it though a clean towel over a 5gallon bucket and reuse it again as this mix is good for like 150K miles or something crazy. Saves money!

Mongler98 said:

When you ever have to do work to your system again, use a clean 3 gallon shopvac to suck up the fluid as it comes out of the hoses, then filter it though a clean towel over a 5gallon bucket and reuse it again as this mix is good for like 150K miles or something crazy. Saves money!

Click to expand...

Thanks for the tip. That sounds a lot easier than the way I have been doing it.

Mongler98 said:

drain, fill, drive till to temp 3 times with distilled water. If its really bad i.e. brown or other crap in the coolant, you can add a small amount of vinegar on your first drain and fill. You can use Iron Out, works well and less damaging then vinegar, other methods are to use LAUNDRY detergent added. if you do add something on the first flush, do 2 more flushes with distilled. then flush with proper coolant. there are many heated debates on what to use and why but the reality is that if the engine and components were flushed properly, that any of the (works for this engine) type coolants is fine. I personally like to stick to OEM rated brands but on some cars that have coolant issues from time to time i use a cheaper substitute as i am changing thermostats or pumps or other parts more often and want to save a few bucks.

Here watch this.
https://www.youtube.com/watch?v=s--5ft5YiHg

Click to expand...

I've used laundry detergent too....it's really good at getting oil & grease and other stuff out...plus it's formulated to be low foaming...