Morris Minor Owners Club

Every car I have anything to do with has years of rusty silty crud built up in the cooling system. I've found Tesco do a bottle of acid loo cleaner for about a quid, was wondering if there's any reason not to chuck a bottle in the cooling system for a day or two (and run the engine enough to circulate it) then flush out and put water/ antifreeze back in.

Overall I can only think that a thin rad core and maybe the heater valve might be in danger, or should they be OK too?

so long as you don't put it in neat i cant see a problem, I would put it in with water (duh!) and turn on the engine, rev it up a bit, leave it ticking over for 10 mins, drain the system, fill it, drain it again and then put the water/antifreeze mixture in. The only things the acid is likely to react with are the alloy componants (thermostat cover and water pump), however with it diluted and with a relatively short exposure time its unlikely to do any damage!

*disclamer* this is my opinion having done A level chemistry and part way through a degree involving chemistry. If it all goes wrong dont blame me!!!

That was my take - I think it's hydrochloric based, and about 750ml. So in a typical old car cooling system (huge capacity compared to modern stuff) I reckon it'll be nicely diluted. Not sure about only leaving it in 10 minutes though - Takes about 8 hours for it to really start descaling household stuff in my experience, although I suppose the extra heat in an engine will speed things up

I'd imagine a lot of the cars I'm dealing with have had plain water used over the years, which in a hard water area like this might have built up quite a level of crud aside from the rust and alloy oxides that seem to be floating around, so some sort of dissolving of these deposits would be nice I'm not convinced by the rad flush stuff I've seen around, very small bottles and not exactly small prices...

It's a bit of a chance ! Sure it's not alkali based - most loo clearers work around sodium hydroxide - very powerful alkali which will seriously react with any aluminium parts. I would just flush out the system with water for fear of doing damage to radiator and heater core - this might not show immediately - just half way up the motorway.

Im sure most loo cleaners are acidic, otherwise it wouldn't be able to remove any limescaly type stuff....

That's true - not a problem up here with nice soft Scottish water !

Definately hydro acid - Thanfully there's a lable on it so I didn't have to taste test ;)

We have very hard water around here, so I use it as a general descaler (as Matt says, alkali would be a bit naff for that job) as well as in the loo.

I'm just a bit worried that to be strong enough/ left long enough to break down the crud in the cooling system, the acid might start to weaken already fragile parts too. But I think I'll get away with it in terms of water jacket, heater and rad, it was more the little things that get forgotten about (stat, heater valve, etc) that concern me.

Flushing with water has moved so much of the junk, but even after a good flushing a couple of weeks later the coolant is back to brown from all the partially loosened muck. When I had the pickup head off the large waterways were literally half to 3/4 full of mushy rust "mud"!

So what is the best method to flush my system?

I'd prefer to not use chemicals...

is a hosepipe down the rad ok?

where do I flush it out of?...the rad tap is so small

Hi guys:

1) There are some copper bits in the system (e.g. thermostat!), so I wouldn't use the acid in there for too long! Alos, it there's a lot of limescale, wear eye protection - you don't want it fizzing into your eyes (wash with lots & lots of cold tap water if you do, then off to A&E).

2) Most of the crud in the engine will be "rust" - iron hydroxides, not limescale, so you won't be able to shift that with acid (nor alkali) easily.

3) Flushing system - to do this seriously, remove the radiator (two hose clips, pull of the hoses - this drains the system). there's 4 botls (two per side) and the whole thing lifts out.

4) turn the radiator upside down, insert hose in the hole at the top & turn on the hose (you may need to stuff some rags into the gap).

5) engine - if you can, remove the pump (it opens up all the passages & gives you a chance to clean the grot out of the pump & see how good the pump vanes are!).

6) remove the hose from the radiator, and flush out all the passages...

7) Read Pyoor Kate's instructions on heater flushing and do that.

Reassembly is simply the reverse of dismantling (spot the quote ).

9) change the thermostat for 82C one, refill with 30% antifreeze, sit back and enjoy the heat!

Colin

If you decide to do it Colins way you should also change the bypass hose at the same time as its much easier with the pump off.

This is just my 2c's....

I've build a few toyota supra engines, and I would NOT use anything other than proper radiator flush...

If you use any old chemical, you run the risk of eating into the metal and causing serious damage, while I realize morris engines are not at the same level as the 500bhp supra engines I've built... I certainly will not be taking the risk with mels...

For the sake of 7 quid for the two part cooling flush from halfords it is not a risk worth taking...

Then flush it out properly with a hosepipe...giving it plenty of time while flushing all the rubbish out..

Then on filling...

Get a good quality antifreeze which is suitable, and then dilute it with de-ionized water (battery water or something) and provided you don't get leaks, you will have a very good system for years to come without any crud building up.

Take it which ever way you want, but it is good practice..

Gav (Moggy_Mel's otherhalf)

Do you have to dilute it? I have never done that, I always use the green comma coolant (coldmaster -36)
I have indeed seen what water does to the car's internal organs

Any idea what the off the shelf flushes active ingredients are? Only I'm still not convinced they're all that cost effective - Bit like Jenolite, where you can pay a fiver for a tiny bottle, or get the same stuff by the gallon for around a tenner from your local agri supplier

Onne,

You should dilute Antifreeze! (but read the instructions)

The freezing point of water is about 0C, the freezing point of ethylene glycol is about -13C.

The freezing point of a 30% ethylene glycol 70% water mix is about -30C

The mixture is also less viscous, so it will flow more easily through the system (less work for the water pump or gravity).

Pure glycol was used (IIRK) for cooling Merlin engines in WW2, but the concern was heat transfer/capacity, not freezing.

All the best,

Colin

Do you have to dilute it? I have never done that, I always use the green comma coolant (coldmaster -36)

I hope you are buying the pre-diluted stuff which you can as well...I certainly hope you aren't use concentrate stuff without water....

It won't have the same freezing and boiling points, in fact the dilution enables it to go as high and long as they quote...

Gav

I use the readymade stuff, we also sell stuff called antifreeze, this is just coolant

Phew,

Had me worried for a second.... thought you were using pure coolant/antifreeze...

That is as good if not better than a concentrate+de-ionized water combination..

Gav

I know some idiot (ok, me) who put caustic soda in his rad, left it for a few days and the caustic soda had eaten away the head gasket, result blown gasket. Just a word of warning when your sticking stuff in your rad.

Hmm,

I forgot the effect of strong alkali on cork (gaskets) - and I've just remembered that the copper ones won't like much acid either ....
(remember those nice blue crytals at school - copper sulphate? - well, copper chloride is just slightly different colour - still dissolves nicely).

Maybe we should stick to kettle descaler - much weaker acid, so less rotting of gaskets/copper etc.


Colin