Ecu is full of engine oil???

I bought an AFN ecu off eBay off an Audi A4
028906021GN with map sensor built in

It's FULL of engine oil! All over the circuit board

Does the hose that plugs on normally fill the ecu with oil???
This can't be right?

No, it does not.

What probably happened is the hose inside the ecu had a split in it, so the air normally in the hose under pressure was allowed an avenue to escape, and then the engine suffered either a runaway or there was excessive oil in the intercooler tract. The oil was then sprayed all over the inside of the ECU due to the hose split.

I don't see another method of it happening. I have seen plenty of split hoses but never any oil. I have also seen oil accumulate in the hose end connected to the boost pipe before the intake but never the two together.

The main PCB was swimming in oil.... amazing...
I can try and brake cleaner it off and see if it works???
Many thanks

Be careful with brake cleaner and even some electrical parts cleaner! Some of it is rough one circuit boards! There's nothing like cleaning a board with electriclean and then the board falling apart in your hands. Try whatever you use on a corner or something first!

I've seen a couple with a very minor bit of oily residue in them from a split MAP hose. Chances are, the car that ECU was in ran like crap, and the owner just kept on driving it and since there was an "outlet" for boost pressure to release inside the ECU, it simply carried the crankcase vapors with it and eventually made its way all the way there.

It took my Mazda pickup about 380k miles for the speedo cable to wick up enough gear lube to have it dripping out of the instrument cluster's backside and running down on to my clutch pedal due to a leaking internal drive gear seal. Similar type issue (except I had no idea anything was wrong).

Non residue electrical contact cleaner would be a way better choice than brake cleaner. Brake cleaner is some really nasty stuff and may severely damage your ECU.

Paint thinner. Fairly benign compared to brake or electrical cleaner.

what kind of paint thinner tho- water, white spirit, cellulose thinners?

You're trying to remove a petroleum product, so water won't work. Use mineral spirits, clean rags/cotton swabs, etc. Be gentle. I've never had to do this BTW, but that's how I'd proceed.

Frankly, there is nothing on a typical circuit board that won't tolerate water, so a sink of warm water and something like Dawn works wonders. The last step in most board manufacturing lines is a water wash to remove the water based flux that is used. I'd just final rinse with distiled water or the purest alchohol you can find to ensure no hard water deposits or residue left behind, and alchohol will help drying as well.

I work on a fair amount of electronics in entertainment, and this works wonders for 'bar slime' (smoke, oils, cooking residue, fog machine residue, etc.) as well . . . and never lost a board doing it for 30+ years.

- Tim

This particular circuit board has at least one pressure sensor on it, however, which may or may not appreciate being submerged in water.

I'm with the previous posters... you're trying to remove a non-ionic (oil), so other light non-ionics, like mineral spirits, kerosene, even diesel for that matter, would work...again, watching out for that pressure sensor.

and try not to dissolve any conformal coatings in the process...

DPM said:

what kind of paint thinner tho- water, white spirit, cellulose thinners?

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DPM said:

and try not to dissolve any conformal coatings in the process...

Click to expand...

Obviously DPM here has something important to say, so maybe he has some helpful information for the class. Or maybe he just wants to impress upon us all his esoteric knowledge of things we must be ignorant of in our pursuit of a viable solution to a simple problem.

Vince Waldon said:

This particular circuit board has at least one pressure sensor on it, however, which may or may not appreciate being submerged in water.

I'm with the previous posters... you're trying to remove a non-ionic (oil), so other light non-ionics, like mineral spirits, kerosene, even diesel for that matter, would work...again, watching out for that pressure sensor.

Click to expand...

Simply cap it, at least if it has an external connection. And frankly, I'd be more willing to get water in a sensor than a solvent, but neither would be good . . .

- Tim

sisyphus said:

Obviously DPM here has something important to say, so maybe he has some helpful information for the class. Or maybe he just wants to impress upon us all his esoteric knowledge of things we must be ignorant of in our pursuit of a viable solution to a simple problem.

Click to expand...

Well, a couple of things. You said "paint thinner". This is an international board, and that phrase means different things to different people in different places.

In the UK- where the OP and I both reside- if you talk to someone in the motor trade about "paint thinners" you'll mean cellulose thinners. In a DIY store it'll be turpentine substitute.

Both will degrease, but one will also remove protective lacquers, soften plastics etc.


Without seeing the board in question I would hesitate to offer solvents into the mix and would likely do as tadawson recommends- soapy water wash, DI water rinse, alcohol dewater, dry.

nothing esoteric, just thirty years of not trying to break delicate electronics in the process of repairing them...

/bar slime. Ha, now that brings back memories. Sepia-tinted images and a final anode cap arcing and smelling of cheap fags. Bleargh.

That is why I recommended electrical contact cleaner. There is a VG chance it will do no harm to the ECU innards because it is formulated for cleaning/degreasing electrical components.

Here in NA, "paint thinner" usually means lacquer thinner which can cause problems with some plastics and rubber.

Does it work?
If so then put in a new hose and let it drain onto a paper towel and run it.
It is possible the oil has done all the damage it will and letting a little remain migh ot be a bad idea.
As another step you could rinse it wilt a little LPS1 which is a thin oil and will dry over time.

Really unbelievable. Read posts # 6 and 16 and do that. Do not use brake cleaner, paint thinner, LPS-1 or WD-40, any of which might cause damage to electrical components.

DPM said:

You said "paint thinner". This is an international board, and that phrase means different things to different people in different places.

/bar slime. Ha, now that brings back memories. Sepia-tinted images and a final anode cap arcing and smelling of cheap fags. Bleargh.

Click to expand...

As you said, this is an international board, and words mean different things in different places. On this side of the pond, that word does NOT mean "cigarettes", as it does in your area.

Ol'Rattler said:

Here in NA, "paint thinner" usually means lacquer thinner which can cause problems with some plastics and rubber.

Click to expand...

Actually, in North America, "paint thinner" does NOT mean "lacquer thinner" - they are two different substances. Lacquer thinner is a "hotter" solvent (may be due to its containing aromatics and ketones) which will attack paint, while paint thinner (pretty much a collection of aliphatic hydrocarbons) won't attack lacquer.

Holy crap. it does not get any easier. Go down to local auto parts store and get some electrical contact cleaner and use that. 100% guaranteed not to harm anything electrical and does perform a degrease function.

I have no clue as to why there is any sort of debate about different types of solvents. This side of the pond or that side of the pond, who really cares. Anywhere you go, electrical contact cleaner is the same thing.

Ol'Rattler said:

Holy crap. it does not get any easier. Go down to local auto parts store and get some electrical contact cleaner and use that. 100% guaranteed not to harm anything electrical and does perform a degrease function.

I have no clue as to why there is any sort of debate about different types of solvents. This side of the pond or that side of the pond, who really cares. Anywhere you go, electrical contact cleaner is the same thing.

Click to expand...

Actually id does get harder than that. A lot of the contact cleaner available contains triclorethylene or trike triclor etc. This will do an excellent job cleaning contacts, but will cause polycarbonates to to crumble before your eyes. Rinsing it off will not stop it from coming apart.
Doing nothing will do ..... nothing oddly enough.
LPS1 will not damage plastics and will dry and also clean contacts.
If the box works now with some engine oil in it the it will probably keep working. However some synthetics will damage polycarbonates as well as we discovered when we started using them in air compressors back in the days when the earth first began to cool and the dinosaurs started to feel ill.
Especially the contact cleaner sold in auto parts stores can have triclor in it.
I have demonstrated this to my electricians many times by spraying an ethernet plug and watching it break up into little crumbles.

Good luck!

Many thanks for all your posts, i'll get some proper electrical contact cleaner!

I use 99% rubbing alcohol on all my computer work.

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