EEVblog Electronics Community Forum

Off Topic Hobbies => Mechanical Engineering => Topic started by: Zeyneb on June 30, 2021, 11:50:21 am

Title: Design of car cooling flush system
Post by: Zeyneb on June 30, 2021, 11:50:21 am
Hi there,

I am thinking for some time to make a system for flushing my car cooling system. One that is able to recirculate the flush compound. My car has motor oil in the cooling system due to a leaking headgasket. I do not want to flush it with a garden hose because the time the flush compound is in the system is really limited. Other products are meant to put in the cooling system and then drive the car around so the engine will heat up and detergents can do their work. The problem with this approach is when there is oil pressure the coolant continues to get contaminated because the leak is still there.

I plan to do this flush as a step in my headgasket replacement procedure. Below is the setup that I plan to use.

(https://www.eevblog.com/forum/mechanical-engineering/design-of-car-cooling-flush-system/?action=dlattach;attach=1231782;image)

You might be thinking I am overthinking and/or overengineering this process of flushing the cooling system. I simply don’t want to listen to comments like that. Especially those where people tell me xyz is “not necessary”. I have thought about this for a while and I’ve decided I do want to make this recirculation system. However as I’m not experienced in fluid mechanics I would like to discus design aspects of this system.

Some thoughts about this setup:

1) The pump I plan to use is a 3-phase 370W semi open impeller pump, LEO ABK50. The 3-phase version allows for speed control with a VFD. I think I should be careful with ramping up the flow rate slowly because an obstruction might build up pressure quickly which can damage the cooling system part on the car.

2) I also read about cavitation. I have already planned to put the pump at a lower level than the reservoir / cooking pan as well as a smooth hose leading to the inlet port of the pump.

3) The regular water pump in the car also has an impeller. I don’t know if it would be possible to lift the timing belt of the water pump sprocket and then force flow along the water pump impeller. Otherwise I might get an old water pump from a salvage yard on which I remove the impeller myself.

4) As my car engine is made of aluminum, both the cylinder and the block. When the engine is cold I think a camping stove would be insufficient to heat up the engine coolant to about 60°С for the detergents to do their work. You know it is not some 100 mm diameter propane cylinder but more like 220 mm diameter cylinder. But still the amount of gas coming out of it is limited. Another thought is to do this flush as soon as possible after haven driven it.

I would be nice to have other people share their observations on those 4 thoughts I expressed. Maybe other things will come to your mind about this design. Please let me know.
Title: Re: Design of car cooling flush system
Post by: langwadt on June 30, 2021, 12:02:56 pm
what  are you trying to accomplish, make a rube goldberg machine for no reason?

just replace headgasket, follow instructions for detergent and be done with it

 
Title: Re: Design of car cooling flush system
Post by: themadhippy on June 30, 2021, 12:05:07 pm
Quote
The problem with this approach is when there is oil pressure the coolant continues to get contaminated because the leak is still there.
fix the problem first otherwise your going to need a new engine
Title: Re: Design of car cooling flush system
Post by: SteveyG on June 30, 2021, 12:59:18 pm
Quote
The problem with this approach is when there is oil pressure the coolant continues to get contaminated because the leak is still there.
fix the problem first otherwise your going to need a new engine

Exactly. You do not need to flush the system prior to replacing the head gasket.

You'll likely get the head skimmed at the machine shop anyway and they will clean the water channels in there. Flush the rest with a hose pipe while the head is away then add the chemicals once it's all back together.
Title: Re: Design of car cooling flush system
Post by: Zeyneb on June 30, 2021, 02:16:52 pm
Maybe you guys have a point. So the idea is to first to replace the headgasket, then
use a flush compound in combination with cheap coolant and then drive around for 500 km or so and then drain everything and put quality coolant in the system. Correct?
Title: Re: Design of car cooling flush system
Post by: Brumby on June 30, 2021, 03:58:12 pm
Exactly.

Change the head gasket so you can keep the oil and water systems separate then treat each for the necessary cleansing.  If you DON'T do this, you will be chasing an ongoing cross contamination.  (The length of time the relevant edges of the head gasket are exposed to polluted oil and polluted water is of no consequence.)

Fix the problem then use the cleansing products according to the respective manufacturers instructions.  (500km is a tad excessive from my experience).

Why try and create a complicated experiment on your vehicle, when there are processes and products already available.  You will end up spending LESS time on the exercise and expose yourself to much less risk .... and it will be cheaper, to boot.