Phosphoric acid in engine water cooling system?!

[Torqu-E-Cycles]

Just had a look at an old steel mini engine block I've got and the thought popped into my head... I wonder if water/phosphoric acid mix would be a very bad idea as a system flush to clear all the rusty crud from the water jackets etc?
Maybe not run the engine hot or even with the radiator/heater plumbed in, maybe just mock up a reservoir and just run the engine until the temp lifts a little then leave it sat to soak for a week before a really good flush through?
Thinking out loud here thats all!

 

[rcx132]

I considered that but there are zinc plated parts in the system like the pump rotor and steel pipe connectors. The acid will strip the zinc. Also acid will descale but won't remove crud.

 

[mike 109444]

And the core plugs won't like it. They will be eatened from the inside.

 

[Keithmac]

I have a coolant filter kit ready to fit to one of my cars, it has cast iron block too.

It will be getting a good flush first and fresh coolant.

I plan to fit it on the entry pipe to the heater matrix (you can't fit it on main radiator pipes as it won't flow enough).

 

[Torqu-E-Cycles]

I have a coolant filter kit ready to fit to one of my cars, it has cast iron block too.

It will be getting a good flush first and fresh coolant.

I plan to fit it on the entry pipe to the heater matrix (you can't fit it on main radiator pipes as it won't flow enough).

Ah that sounds like a good idea! Will have a look for one!

 

[prepman]

I have a coolant filter kit ready to fit to one of my cars, it has cast iron block too.

It will be getting a good flush first and fresh coolant.

I plan to fit it on the entry pipe to the heater matrix (you can't fit it on main radiator pipes as it won't flow enough).

A side-stream filter as it's known on large cooling systems..

 

[Ross365]

I wonder if the sort of product made by Fernox for use in flushing central heating systems could be used? I suspect that such solutions are alkaline rather than acid, but a really good commercial product like Fernox might well be quite a cocktail of constituents to get the best effect.

 

[northwest]

We used to use Nitric acid as a descaler, very effective it is too.

 

[Ubique]

Just remember that whatever you put in, you will not be able to get it all out without completely disassembling the coolant system & engine - so there will always be some in there. You can minimise it by filling, running & draining several times, but there will always be a trace in there so choose wisely, look at the composition of the specified coolant and take guidance on how the 'flush' will react with it.

 

[Keithmac]

This is what I have ready to fit.

The filter is quite big, similar size to a large canister oil filter.

It is a specific kit for a Ford 6.4 Powerstroke but the bracket looks easy to mount and the lines are long (1m) so easy to cut down for my application.

You have to be careful with replacement filters, some have a slow release additive package inside, you want a straight filter really.

I plan to run first filter 1000 miles then change every service (possibly every other depending how they come out)

Need to buy a filter cutting tool really so I can inspect the filter media.

 

[prepman]

Just had a look at an old steel mini engine block I've got and the thought popped into my head... I wonder if water/phosphoric acid mix would be a very bad idea as a system flush to clear all the rusty crud from the water jackets etc?
Maybe not run the engine hot or even with the radiator/heater plumbed in, maybe just mock up a reservoir and just run the engine until the temp lifts a little then leave it sat to soak for a week before a really good flush through?
Thinking out loud here thats all!

Isn't phosphoric acid the base for rust treatment products containing zinc. Kurust for one? Construction teams used to passivate cooling systems prior to cmmissioning so always done for me. Never took much notice what they used.
Zinc + Hydrochloric acid is 'killed spirits' or tinman's flux for soldering.

 

[prepman]

Just remember that whatever you put in, you will not be able to get it all out without completely disassembling the coolant system & engine - so there will always be some in there. You can minimise it by filling, running & draining several times, but there will always be a trace in there so choose wisely, look at the composition of the specified coolant and take guidance on how the 'flush' will react with it.

Bi-carb to neutralise and ph test?

 

[prepman]

And the core plugs won't like it. They will be eatened from the inside.

Easy enough to replace or were. If the block is badly corroded they might need replacing first?

 

[prepman]

I considered that but there are zinc plated parts in the system like the pump rotor and steel pipe connectors. The acid will strip the zinc. Also acid will descale but won't remove crud.

Zinc plated? Not alloy?

 

[prepman]

I come from an era when anti-freeze was only used in winter and drained out in summer...all-seasons wasn't around then. So cooling corrosion was staus-quo and plenty of flushing compounds abounded. Cooling systems like oxtail soup weren't that uncommon.

 

[arther dailey]

I was told dish washer cleaner is best to flush, cleans while doing no harm, but never tried it as uncertain on contents , supposedly cleans rad/heater matrix well.

 

[rcx132]

Zinc plated? Not alloy?

Which bit? My current buggy build uses 1990s Suzuki platform and the pump rotor and parts of the pipework to the rad are definitely zinc plated steel.

 

[bricol]

I've never really thought about it before, but gylcol based coolants will strip zinc from plated parts - hence while carbon steel heating/cooling systems in machines/buidling might be zinc plated on the outside, they aren't on the inside.

 

[bricol]

I come from an era when anti-freeze was only used in winter and drained out in summer...all-seasons wasn't around then. So cooling corrosion was staus-quo and plenty of flushing compounds abounded. Cooling systems like oxtail soup weren't that uncommon.

Crikey - you must be getting on a bit - antifreeze as a permanent, year round coolant, was around in the late 1920's.

 

[bricol]

I've had to research a lot of cooling based stuff recently - redesigning a cooling/heating system on a £3m machine to save money, make it less complex and more efficient.

Plus my own car - I shoved more "modern" pink coolant in my Lancia 8 yrs ago when I put it back on the road - had to drain it a couple of times and I've never seen such rusty looking coolant, or so much rust deposits in the engine bits - so its being flushed and run on plain old water this week, ready for a swap back to ethylene glycol stuff.