Descaling the engine block?

[rayofleamington]

Hi,
a month or 2 ago there was mention of someone planning to freshen up their block with caustic soda in the water jacket to remove problem rust and debris.
Did anyone ever try that?
Is there a risk to do that on a 'modern' engine? (eg Volvo with Renault 1721 turbo engine?)

[Willie]

I have successfully used 'Kettle descaler'solution to soak
engine blocks overnight,ditto the heater cores. The descaler
contains Formic Acid. I do not know if it would attack'modern'
engines which probably contain loads of Aluminium
Willie

[Chris]

I've never heard of this, but it seems to be used best through electrolysis (a bit like chemistry class), but is meant to be quite good at stripping rust from smaller parts.

And as willie says it will attack the aluminium as well as the rust.

Theres more detail on the electolysis process at http://www.alphalink.com.au/~petero/rustconverter.html


Chris

[olonas]

It was possibly me with an accumulation of sludge at the back end of engine cooling water spaces preventing water coming out of block drain tap/plug I used kettle descaler suggested by Willie. Wasn't it phosphoric acid Willie? Had to remove cylinder cover and fill block with solution, left for 24 hrs. It probably helped but I still had to prod around at the back end to encourage proper draining. Before pickling, however, prodding and poking had no effect.

[an_avenger]

Alright all -

Right 'caustic soda' is basically solid sodium hydroxide - highly concentrated (about 98% sodium hydroxide solid) and highly corrosive DON'T GET IT ON SKIN OR EVEN WORSE YOUR EYES!!!!! It's the strongest alkali (opposite to acids)

Iron carbide (better known as steel) will react with sodium hydroxide - you'll get a 'rust' colour

Aluminium is worse - the reaction with this highly reactive metal (to chemists it is very reactive esp to acids!!!!!!) is very reactive so chemically leaving caustic soda overnight would have detrimental affects - however if you are stripping the engine to bits it's great washing off oil and grease! In fact the reaction would produce soap!!

I don't do pharmacy at Uni for nothing!

Mind you kettle descaller is less potent (phosporic acid or formic acid) and I have used that to clean my radiator and head!!!!!

[rayofleamington]

Aha,
Sorry for my confused memory - It was kettle descaler that was previously mentioned.
I'd not read the contents of caustic soda, so thanks for pointing out that it's an alkali - rather obvoius now you mentioned it.
From my degraded memory of Chemistry, I'd need an acid (lots of agressive hydrogens) to remove the oxygen part of the iron oxide and therefore break down the rust.

I'm a bit nervous about the effect of strong acid on all the aluminium (head, water pump, etc..) and I was trying hard not to have to strip it down.
I guess I'll have to think long and hard about that.
I might try a few aluminium test pieces first (eg the old water pump, covered in 1/8" thick crusty redish brown deposit).

I'll let you know how this goes on when I get time.
I Have to change Gayle's gearbox first + a few other things like Christmas shopping.

[Cam]

an_avenger,

I had my old Ital engine block 'acid dipped' by the engine machinist (MED in Leicester) do you know what chemicals they are likely to use? and more to the point how effective it is?

Maybe they too use an alkali, but the term 'acid dipped' is used for easy understanding by the customers?

[Willie]

OLONAS...no,it was FORMIC ACID...I originally said
Phosphoric acid which was wrong. Phosphoric is the
basis for 'Jenolite' which is a very efficient rust buster
BUT it is neutralised by water,so, unless you can fill
the entire engine block with neat Jenolite it is not
suitable.
Willie

[olonas]

Correct Willie, now I recall. After all, it was a few weeks ago, lots of the old grey cells will have disappeared forever since then! I think the kettle descaler helped anyway. The rubbish wasn't moving until after the pickling, even after removal of the head poking around before the addition of the mixture had minimum effect.

[an_avenger]

Hello again guys

After researching I have found out the two types of chemical dips used for metal cleaning and resoring are;

n-propyl bromide - (don't ask..... its something very nasty and highly toxic but excellent for removing anything esp grease and oils!) and

sulphuric acid - (a highly corrosive acid which removes oxides, including rust and more of less anything on the metal - it's sprayed on as a vapour and washed off, you get pure clean metal afterwards! Once again try not to drink this stuff........ )

It's good stuff but you need somesort of permission from the big cheeses in Whitehall to get this! So no DIY I'm afraid!

NOW YOU CAN WAKE UP AFTER BEING PUT TO SLEEP WITH THIS BORING RUBBISH!

[rayofleamington]

Well here's an update, I picked up some OUST kettle descaller.
I tried it on the old waterpump but all it did was soften the crusty build and not actually shift any of it.
I was execting some fizzing (well I was expecting huge fizzing and half the aluminium to dissapear...) but nothing really seemed to happen except for a few bubbles from around the steel shaft.
I'm guessing the deposits could partly be aluminium oxide as well as limescale (aluminium oxide isn't going to be something you find in the moggy cooling system ) but still I'll try a few more products and if anything seems usefull I'll give another update.

[Willie]

I think you are right because when I treated my iron block
there was a very vigorous fizzing and abubbling until it had
done its work
Willie

[an_avenger]

Have you thought of using 'Viakal'? I think you can get it from J Sainsbury's! The problem with cleaning Aluminium is that the oxide layer which covers the aluminim metal is protective thats why it's unreactive - but aluminium metal is highly reactive. For large crustings of oxide on the metal you should use and acid but becareful not to spill on 'healthy' metal as this will weaken the metal!

[rayofleamington]

Viakal was on my mind, but like many products it doesn't say what's in it! I used it on a shower head once and was rather unimpressed.

Some of the appliance descalers were citric acid, which sounded a bit on the weak side so I've ignored them.
I'm looking at a few household limescale removers (with Sulphamic acid) plus a handfull of automotive products that claim to remove rust and limescale (Holts, Barrs, Halfords 2 part).
If any of them shift the deposit on the waterpump then they'll get used on the car.

I was tempted to use Parazone limescale remover, which does impressive things to toilet limescale but as it contains Hydrochloric acid I don't think it would be good for the hoses!!!

[Willie]

Did your 'OUST' contain Formic acid?? the advantage of
this acid is that it does not attack rubber.
Willie

[rayofleamington]

Hi Willie,
I'm not sure what the OUST had in it, as with many others they don't tell you what you're actually getting.
Anyway, here's the semi-sceintific results (following the recommended instructions for time and concentration but done in a plastic bucket using the crusty waterpump housing):

Auto-products:-

Holts > No fizzing, no removal
Halfords 2 part > No fizzing, no removal
Barrs > Fizzing from the rusty steel shaft and bolt holes but little effect on the main deposit.
Wynes > Didn't try it at £4.99 !

Household products:-

OUST kettle descaler > limited fizzing from the steel shaft.
Lime Lite Appliance descaler (sulphamic and citric acid)> Strong Fizzing from the rusty steel shaft and bolt holes but little effect on the main deposit.
Parazone limescale remover liquid (hydrochloic acid!) - only used because I had some and wanted to know what happened, I wouldn't recommend it > Strong fizzing from all metal surfaces but still negligible effect on the deposit.


On the basis that only Parazone reacted with the aluminium, I'm less worried about my aluminium engine bits.
I guess the scaly deposit also includes aluminium oxide so maybe there isn't anything that will shift it on a fully assembled engine.

Barrs was amongst the better performers, and it is intended for the job.
The instructions on Barrs say it can be left in between 2 and 48 hours so it can be done one evening and flushed the day after, it will have more time to work and so that's the one I went for. (the others auto products are only 20 to 30 minutes) .
I doubled the concentration (well I don't always stick to the rules). I only left it in 8 hours as it was going to freeze last night, but it was fizzing the whole time.

[Willie]

Good luck.... hope you don't end up with a single cylinder
two stroke!!!
Willie

[newagetraveller]

Have you considered putting water pump plus descalent in an iron saucepan and warming it up to speed up the reaction?

[rayofleamington]

I did wonder about the heat factor as heat will generally speed up that kind of reaction.
Unfortunately I ditched all my old pans when I had a new kitchen so only have nice stainless ones now - which I didn't want to use for hot acid testing
To get around that I preheated the pump to 100 degrees and used boiling water in the bucket. It was still about 50 degrees by the time 20 minutes was up, but it only really took 60 seconds to tell if anything was going to happen or not.

It makes you wonder if certain products actually do what they say on the tin. I would hope that they have some effect in loosening and suspending the sludge (the other claim on the tin), as they didn't do what they said regarding removing any corrosion.
At the end of the day not many people would ask for their money back as how would the average punter know that it didn't work?

[rayofleamington]

Thanks for the advice + some pleasant news!
The Volvo now runs better thanks to the treatment. The coolant temperature hasn't really changed but It can now do constant motorway speed without the oil temp rising too high. (still not as good as it once was but I wasn't expecting miracles)
Unfortunately the solenoid/starter packed up today after I'd had the car fixed for less than 24 hours!!

Thank heaven's for the trusty Morris, which is getting quite used to it's every day use ('trusty' now that the loose dizzy, fialed petrol pump, battery, headlight and thermostat have been fixed).

I can't wait until antifreeze isn't needed again so I can also give the Moggy a few days treatment with Bars.