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  Engine Cleaning

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Cleaning the Engine and Karcher Syndrome

A question that constantly crops up is the subject of cleaning the engine. The engine bay is subject to a gale of air through the radiators and dust, dirt and oil fumes combine to create a heavy grime. Owners often ask for advice on the best way to clean the Scorpio engine.

Reproduced below are some samples of Mail List conversations.

Faulty alternator:

My car (24V) had a lot of leaks, water and PS fluid dripping into the Alternator when I had it - all cured but I intend to take the Alternator off the car and give it a good clean out before I change it.
If you have had fluids dripping into the alternator or the engine has been steam or pressure cleaned it is worth  checking, only problem is you do need to get the Alternator off of the car to get a good look at it - then you
may think you only want to do it once. As Eric says you really must check carefully you get the the correct replacement.

Chris N


Grrrrrrrr. Steam or pressure cleaning? Don't even think about Karchering the engine bay.

Doing such can seriously lighten your wallet, smack your plastic, or make your bank manager cry.



Hi Eric,

I was told by a FMD that my engine needed cleaning & that I should have it steam cleaned.

Any Suggestions?




Now I've got my blood pressure under control again and restarted my pacemaker, I can talk about Karchers.
They are excellent machines. I have one. But they are for cleaning patios, concrete, windows 18 feet up and scaring the poop out of next door's cat. They are NOT for engine bays. I'll reproduce an earlier mail:

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You Karchered it ????
You were very lucky that this was the only mishap.
Pressure washers are useful for wheel wells and general underside areas - but the engine and auto gearbox are connected by looms of thin wires which carry low voltage signals. They connect the many and varied sensors which provide the EECV with the signals it needs in order to function correctly, and these multiplugs are so important that Ford pioneered the aircraft-style positive-pressure multiplugs filled with a waterproof inert grease that will not corrode the gold-plated connection pins.
The problem with the pressure washers is that they are powerful and indiscriminate, and can flush out the grease from multiplugs, force their way into the looms and create 'ghost' signals, and you can end up with varied weird symptoms which are almost impossible to diagnose and can be very heavy on the wallet. I would check all the multiplugs you can find - open them and make sure that they are still filled with the clear grease. If any are wet then buy some non-lithium multiplug grease, dry them and re fill with grease before the corrosion sets in. Do not use ordinary electric grease - it will lift the gold-plate from the connections and cause you grief.
Then make a mental note: I will not Karcher the engine bay again. :-)

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But instead of high pressure water, they advised you to use pressure steam?
Oh, good idea. They're rubbing their hands with glee on the way back to their tea room. I can just hear the conversation -
"You told him what? Hahaha"
"Yep. Give it till next week, and he'll come back popping and spluttering ..."
"Hahahahaha -"
"... The engine is running rough ..."
"... and that'll be seven hours on the WDS, 1 a minute. New alternator with a bit of luck, maybe a nice juicy loom job across the engine bay - "
"That's if we can find it, hahahahahaha"
"Yep. Should be good for another MAF and even a CKP ..."
"HEHEHEHEHEHEHE. That's just for starters."
"Yep. Should take months before all the wiring is dry. And then there's the C110 and C112 -"
"Oh yes, lovely. They should corrode a treat."
"So then we're into next year ..."


Catalytic Meltdown

Recently a new owner collected his nice low-mileage Cosworth from his car dealer. During a long journey and a week away from home his engine became increasingly erratic, misfiring badly, and worsening every day until the car was almost undriveable and he saw a catalyst glowing red hot at the end of a journey. The owner eventually found that the dealer had pressure-washed the engine bay and water had filled the spark plug housings, shorting out the HT and caused the serious misfire.

The effect of a high speed misfire is that unburnt petrol vapour covers the catalyst washcoat, which is then ignited by the next firing cylinder, and the temperature of the washcoat can be increased by 800C, which is what happened to this catalyst and why he saw it glowing red hot. It will be a miracle if the catalyst - and the HO2S sensors, which are based on similar technology - have survived intact. Catalysts at 300 a  time and HO2S sensors at 100 - that is bad news. In his case his dealer has apparently put his hands up and will meet the cost of the new parts - we hope.

...And there's more

What else could happen? Oh, lots more yet. The springs inside the drive belt tensioners and the bowden cable and lever for the bonnet release will now start to rust. The commutator brushes and field coils inside the alternator have just received a right good soaking so they'll be ready to pop the diode pack and/or corrode the front or rear bearings. Any of the connectors for the INJectors, the CKP tucked right down by the crankshaft pulley, the ECT, IAT and TP sensors at the top of the engine and the electronic ignition system EDIS  at the front - and the major square connectors on the drivers side of the engine bay wall, C110 and C112, may have had the waterproof grease driven out by the high pressure detergent. These are now free to collect moisture and to corrode very slowly. The spark plugs, especially on the Cosworth, are sitting in water 2 inches deep and shorting the HT nicely to earth. Odd errors may start to appear especially after heavy rainfall, some sensors producing LOS so that the car only manages 10 miles per hour. As if this weren't fun enough, the autobox may start to show symptoms, too, like dropping heavily into gear or refusing to select 4th. All of these corrosion-induced faults can only get worse as the gremlins multiply ...

Okay - So How do I clean the Engine?

Lock the hose away and don't even think of using a pressure or a steam washer. The proprietary cleaners are expensive, too, and many need rinsing down with a hose, so leave them on the shelf. All you need is a little patience, a gallon of paraffin and a cut down 1" paintbrush and perhaps a radiator brush for awkward areas. Remove the under-engine cover, spread paper beneath the engine, and take off easy to remove items, like the air inlet hose.

Work the paraffin into the grime starting from the top of the engine to the bottom, jack up the car onto axle stands and then work underneath. Wipe off the paraffin with old rags and dispose of these safely.

Paraffin is an excellent degreaser, but it is virtually inert, does not produce heavy fumes and dries nicely. Using the brush you can control where it goes and it will not effect the multiplugs because it is not under pressure. Below are pix of the above and below for my Cosworth. In the six years I have owned it it has never seen a pressure hose, steam or spray engine cleaner. I have the same paraffin I bought ten years ago and its a deep black colour by now, but I pour it back into the container and it's ready for degreasing any time I need it .

I collect the paraffin I have used where I can by letting it drip back into a container. I leave this for a day or so to let the particles settle out, then I decant the paraffin back into the original container.

NOTE: If you check the connectors and find them dry without the waterproof grease - do not use lithium based grease! Use Nyogel 760A, or order it from Ford - Finis 5 030 186.


An engine bay doesn't look like this by accident

... and underneath is pretty clean too.




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