flushing the coolant system

Is it realistic that you can expect to dislodge anything in the system just by flushing it with a hose? I'd have thought the answer to achieving that is some kind of chemical flush but that carries obvious risks if there is a weakness in say a heater core etc. I'm not sure I'd do it if the car is cooling properly & if I was going to do that I'd remove the radiator & just descale that off the car as a first attempt. If all you want to do is change the coolant then I'd drain as much as you can, refill it with water , run it, drain it, refill it with water , run it etc etc. You are going to clear all the old coolant out after 2 or 3 cycles.

After that you just refill the thing with good quality coolant & (preferably distilled) water & bleed it. You will clear most of the air out of it pretty quickly. The most likely location for an air lock is the heaters & you may have to disconnect a hose there to let it out, but aside from that nothing special & just bleed at the Tstat housing and the radiator. Having it on a slight slope, nose down can also help.

 

I have owned several vehicles for over 20 years each. I've owned my 328 for 30 years. They are/were Mercedes, a Ferrari, and a Porsche. I have never flushed a cooling system and I have never had a problem with corrosion. These cars have block drains so the amount of used coolant remaining is very little. I only drain completely and refill with new coolant. I've never had to descale a radiator. Back in the late 70's I used a chemical flush on my 351 Ford engine. Shortly after the heater core began leaking.

 

I agree with the comments above. Personally, I would never induce tap water into the coolant system. You will never get it all out. The minerals in water is what produces scale deposits. Drain the coolant system every few years and always use distilled water or premixed anti-freeze. I have never used any type of chemical flush and never need too.

 

I would always use distilled water, its so much safer than ordinary tap water
If the water quality is unknown in the car then I would in the first instance fill and flush with DW as well. Any residual "tap" water left in the system after the initial drain will negate what you are really trying to do.
Try getting an old rad cap and fitting a hose connector on it, then fit to expansion (header) tank and fit about 3m of vertical hose and a small receptical, then add water via this elevated tank. The extra height adds about 5psi pressure to the system and usually forces out all the old fluid + its also a great way of clearing the system of air.
Tony

 

I just put in a new radiator and changed all my coolant hoses. I wanted to do a leak test so I filled completely with distilled water, ran the engine to operating temp and when I drained it afterwards it looked like antifreeze mix. So there was still a lot of residual in there somewhere meaning that if you were to power flush with a garden hose you'd probably never get all the tap water out as noted above. Distilled water is cheap at the grocery store, you can fill and drain a number of times if you feel it's necessary. I don't think forcing tap water through under pressure is really going to do anything beneficial for you.

 

I collect all the condense water from my de-humidifier...............its free

 

And what is the approximate total volume of the cooling system ? All bits included.

 

Note that if you have issues with rust or scale, water isn't going to do much for you except remove loose deposits. You'll need to use an appropriate acidic cleaning chemical.

 

Rust or scale in the radiator isn't the major concern here.

Cavitation is the problem

 

With the engine off and the internal pressures low, I don't forsee a problem with cavitation resulting from use of a garden hose.

Not that I'm endorsing the garden hose plan, btw. A proper power flushing with solvents is the better approach.

 

22 or 23 litres from memory - its in the handbook I think. I also use water out my dehumidifier mixed 50:50 with good quality antifreeze. The antifreeze has anti corrosion & stabilising agents in it as well anyway these days.

 

The cavitation issue is one caused by service neglect and using the wrong coolant, if I'm not mistaken.

 

It can be caused by several things, and one of them is certainly mixing two types of coolant in the system. However, flushing with water with a garden hose and/or simply draining it from the block is not a completely effective solution to getting all of the old coolant out of the system.

If he's going to replace the old coolant with identical coolant, then cavitation isn't going to be an issue in the first place as far as mixing two different types of coolants.

If cavitation has already occurred and caused damage due to this or other reasons, then of course flushing the system isn't going to do a damn thing about it.

In the end of it, flushing the system in this manner is better than doing nothing (again, replacing with identical coolant) but it's hardly as effective as doing it in the manor that a professional would do it with the equipment that a professional would use. You'll remove some loose deposits, but it won't do anything about scale or rust if it's already in the system. You'll get most of the old coolant out, but if you're changing coolant - you might not get all the old out and you'll be making things worse. So ... why go to all the trouble of rigging up some hose in the driveway to do all of this work, when the result is basically not much at all. Except a big puddle of hazardous chemicals in front of your garage.

 

You refer to tools that professionals use ..what are you referring to ...the only tool I know is various vacuum type tools ..big and small ...I don't believe they really remove all the coolant due to the physics of non collapsible heads and passages

Thoughts ? Thanks in advance

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Thanks

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