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MG Midget and Sprite Technical - Cleaning

"Technical's dying, so I thought I'd just say hello, until another thread comes along :).

You're right Lawrence it is a bit slow. Is it because the people are drinking wine and watching the box instead of mucking about in the shed?

Anyhoo this has a sort of technical flavour, so here's my 2 cents. I found it interesting.

A mate came up to The Shed today to deliver a BMW bike that needs temporary shelter. I have a cylinder head from a Ford Sabre marine diesel on the bench waiting on spares so we had a chat about it. BTW he is an ex Royal Marines mechanic and good bloke - he's in the same LifeBoat crew as me.

This is easily the worst-fouled head I have ever seen. The manifold chambers behind the valves are packed with rock hard carbon deposits. The backs of the valve heads are the same, especially the inlets. Huge lumps of baked-on carbon. I tried to take photos to show you but my only camera is my phone and it's not good enough.

I mentioned that I had been trying all sorts to get rid of the carbon - even attacking it with pinpunches and a light hammer and he just went "Mr Muscle Oven Cleaner".

He told me that in training in the RM they would fire thousands of rounds through heavy weapons (GPMGs etc) and they were nearly impossible to clean afterwards as they got so hot. Some oldtimer told him about the oven cleaner and it worked. He said "By the way it's good for decoking cylinder heads as well".

I tried it today on a random selection of the valves. Holy Moly, he's right! It softens the crud so you can scrape nearly all of it off with a scrap of wood.

Tommorrow I'm going to treat the head chambers. I'll let you know how I get on - wish me luck please.

BTW I read the safety data sheet online for this stuff. If you use it wear kitchen gloves and safety glasses - it's seriously nasty. And no way would I let it anywhere near an aluminium head. Just NO.

Any comments? I'd be super-interested to know the experiences of others.

Is it any good on ovens?

I've actually spent more time in the garage during the last week than in the previous three months.
Dave O'Neill 2

I went out to mine yesterday (although we call it a garage), got in the Frog and drove to the library. And back. And the car ran like a top. No technical issues at all.

It's surprising the alternative uses you can put products to. This one's a keeper.
Martin Washington

x2 Dave. I now have a kettle in The Shed! Oh Joy! It's a natural law that tea tastes better whem made in a shed.

As to the effect on ovens I'll give any left over to the Boss and let her decide!

Happy New Year when it comes.

Cheers Martin. It's a happy discovery for me.

In order to make space for the bike I had to shift Don's Triumph GT6 so while I was at it I took it for a 30 mile run.

Rediscovered the sweet joy of the overdrive! God help me I've fallen in love again. How I wish it was mine.

On alternative uses the best thing I've found for corrosion prevention on things like hydraulic connectors on brake calipers for example is Scotchkote liquid electrical insulator. Just paint it on. And Tippex is brilliant for making timing marks. The stuff is nearly indestructible.

>so while I was at it I took it for a 30 mile run.<

Very good of you to make the sacrifice of your time ;-)

Many happy miles in the coming year to all.
Martin Washington

"Rediscovered the sweet joy of the overdrive!"

Indeed. I'm currently enjoying that on my latest MGB. The other one will have an overdrive gearbox when it finally goes back together - I bought the gearbox in 1986!

You could always fit an overdrive 'box to your 1500!
Dave O'Neill 2

There's the oven cleaner that is used in a sealed plastic bag - really vicious chemical that works well on carbon encrusted cylinder heads. I have used that, but there is also a milder version in a trigger -spray bottle which is less aggressive. It still does a good job on aluminium piston tops and l have also used it on carburetor bodies, using an electric toothbrush to work into the little corners and crevasses.
Guy W

Thanks Guy. That's interesting. I have the trigger-spray version ATM.

I was still a bit cautious about leaving it on aluminium for too long. I sprayed it on and began working it with the toothbrush and with some scotchbrite pretty well straight away - as soon as it began to soften the carbon. (wearing gloves!) It does bring up a nice shine though!
Guy W

Mr Muscle is a darned fine paint remover for model paints

Doesnt harm plastic but wrecks the paint film instantly

I knew about using it on well fouled Gimpys too

Keep it away from eyes and other sensitive...

Well you know what I mean
Bill sdgpM

Easy off oven cleaner is fairly popular with the old school motor heads

The reason you dont see it being used to much today is it can reik havoc on modernday vacume hoses and electronics

That said they do make an envior friendly oven cleaner that does okay but wont screw stuff up as bad as the old orginal oven cleaner... just make sure to tape and plastic off sensitive stuff like ignition systems
Prop and the Blackhole Midget

Great comments gents - thanks all.

Well, the valves are now all sparkly clean. I made a start on the head chambers but I'm cautious as the manifolds are still attached and the inlet is cast alloy.

It's good so far though.

I went to the boat this afternoon and did 3 of the piston crowns, being super-careful to use grease to prevent anything unwanted going down the bores. Tomorrow I plan to have a monster hangover until about lunchtime, so further progress will have to wait until I feel strong enough to put my boots on. I'm still waiting on spares anyway.

Dave O'Neill it's torment to know that the exact gearbox and overdrive I want for my 1500 is sitting 8 feet away!

I printed off Guy's brilliant article on how he did it some time ago and it's in my motor-porn bucket-list folder. One day I'll find the bits I'm sure.

The GT6 has the same size motolita steering wheel as my car but with a beautiful wooden rim. I wonder if he'd notice if I swapped them...

Cheers All.

Greybeard, for an O/D installation you might find this info more technically detailed than mine:
Guy W

Thank you Guy. But I have to say I like your article. I was just re-reading it.

I looked into using Mr Muscle years ago to clean some pistons, but backed off as I read it attacked ally. But from what Guy's saying, it's safe.

Wish this thread had come up sooner, I've just almost finished re-building my spare engine, and spent loads of time getting carbon off. :(.
Lawrence Slater

I guess it is down to common sense in how you use it. I wouldn't apply it to bright clean, degreased alloy. But when the piston top is protected with a layer of carbon then it attacks and softens that first before really coming into contact with the alloy. When it does, its only for a short while - assuming you clean it off properly and don't leave it submerged in cleaner for hours.

Anyway it is less harmful than my ham-fisted efforts with screwdrivers and Stanley blades which invariably left scores and scratch marks in the surface.;-(
Guy W

" -- it is less harmful than my ham-fisted efforts with screwdrivers and Stanley blades -- "

Exctly why it takes so long. I used a mixture of s/steel wire wool on the outer layer of carbon and then a green nylon scourer near the surface, and a white non-scratch to finish, combined with carb cleaner and parafin.

But I'm pulling the Midget off the road next week, to get it ready for sale. Whilst I'm about it, I'm going to whip the head off and pistons out(possibly re-ring them) and double check the head for hardened ex-valve seats, so that I can state exactly what's what in the engine. I'll use Mr Muscle and see how much easier it is.
Lawrence Slater

Yes, I also use a range of other stuff like wire wool - not good as it breaks up and gets down the bores, even with grease smeared around the piston lands. -3M scotchbrite of various grades, paraffin, nylon cup brushes,plastic spatulas etc all with varying degrees of success. Given long enough one can get a finish that looks reasonable enough, until you compare it with an out-of-the-box piston.
Mr Muscle is just another weapon, and at the opposite end of the scale to a burred flat bladed paint tin opening screwdriver!
Guy W

I had my pistons out, so a lot easier.

Is a polished crown better then than the factory finish of concentric rings?
Lawrence Slater

I hope that's not a euphemism!

The books say that a polished piston top absorbs less heat and doesn't build up the carbon as quickly
Guy W

Lawrence Slater

Just to close out on this topic. The oven cleaner was working all right on the valves and the chambers in the head.

But I had been in the habit of soaking the the head with a really good spray of WD40 in between sessions to keep the surface corrosion at bay. To my surprise the WD40 (left overnight at least) softened the carbon just as well as the green gunge. Even in the exhaust chambers where it was much harder than elsewere.

On balance I think I'd try that first next time.

Talking of cleaning, - here's an idea, something that I do. I have one of those small plastic tool boxes, about 12" long with a clip fastening top and a lift out tray. So?

Well I keep it on the workbench, permanently about 2/3rds full of engine degreaser/ paraffin mix. I drilled drainage holes in the lift out tray and keep several small brushes there, and a small kitchen sieve wallows in the murk below. Its great, and convenient for cleaning small parts which I just drop in there and leave for an hour or two, or often overnight, and then drain off in the top tray. A basic and very clean and convenient worktop parts cleaner always at the ready.
Guy W

Another use I found for oven cleaner is to clean off stubborn brake dust. When I got my Volvo V70, the wheels were pretty black, and several solvents failed to make any difference. But, the oven cleaner worked pretty well.

According to the instructions, there is a big difference in time required dependent upon temperature (max 200 dF for my product). So, it probably would have worked better if I had used a heat lamp or the like.

I should say that although the wheels are alloy, they are factory painted.

C R Huff

I've wondered about brake dust on wheels and what makes it stick. I know a number of people who have grumbled about cleaning brake dust off wheels, my neighbour was one with his Vauxhall and painted alloys and he used to pressure wash them to get them clean as that was what was required apparently. My experience at the time wash with my Lancia Delta turbo and the brake dust on those painted alloy wheels just wiped off cleanly with a wet sponge and they just needed a rinse after. Whether it's a brake pad formulation issue or what the paint finish is I don't know but the difference in ease of cleaning was significant.
David Billington

Guy - that's a really nice idea. I have an empty plastic toolbox under the bench just waiting for that.

Charley - next time I have to do SWMBO's friend's Honda I'll try that. The Honda wheels are not easy. But SWMBO's POS Ford's wheels are easy - the gunge basically wipes off.

I've known SWMBO and her friend for 38 years but I have never known either one to clean a car properly.

The makers of WD40 claim that it cleans brake dust off alloy wheels.

I haven't tried it, so can't comment.
Dave O'Neill 2

Indeed it does Dave, as long as it hasn't been there too long. But I never much liked the idea of using WD40 so near the brakes.

WD40 does soften and shift tar-spots pretty well tho'.

This thread was discussed between 30/12/2015 and 08/01/2016

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