Black Oil in Coolant Reservoir

[connor_199]

Hi all,

I am just a normal guy trying to fix my car without taking it to a garage, I have little experience working on cars but have done bits over the years. I followed some online guides on how to do this. I have not bought any parts yet. I am thinking about purchasing the following from eBay for less than £80 Total:

1. Oil Cooler - non genuine part
2. Engine Oil 5W30 - TRIPLE QX Fully Synthetic
3. Oil filter - cheapest
4. Coolant G12 - cheapest

Symptoms:

• BLACK OIL IN COOLANT RESERVOIR
• N0 MAYONAISE SUBSTANCE IN OIL FILLER
• DIPSTICK LOW - NORMAL OIL

Back Story:

An apparent Audi Tech viewed my car as a prospective buyer and noted oil in the coolant tank. I have asked an "Audi specialist" garage for an opinion on the oil in the expansion/coolant tank. They believe the oil cooler to be the most likely fault. I have not removed or tested the oil cooler - yet.

Today:

• REMOVED & CLEANED EXPANSION TANK WITH KEROSENE - THEN FLUSHED WITH WATER AND RE-INSTALLED
• PULLED OFF LOWER HOSE
• FLUSHED SYSTEM WITH HOSE CONNECTED TO EXPANSION TANK 'OUT HOSE'
• FILLED WITH DISHWASHING TABLETS AND HOT WATER
• RAN IT UP TO 90 DEGREES AND LET IT CLEAN OUT RESIDUAL OIL
• FLUSHED THROUGH WITH HOSE A HANDFUL OF TIMES
• WAITED UNTIL WATER RAN CLEAR FROM LOWER HOSE
• PUT IT ALL BACK TOGETHER

Issue:

• HEATER STOPPED PUTTING OUT HOT AIR (POSSIBLY LOW COOLANT OR AIR IN SYSTEM)
• I DECIDED TO DRIVE THE CAR UP THE ROAD TO TRY AND UNSETTLE THE AIR (IF IT WAS THE AIR CAUSING ISSUE) - IT WENT INTO LIMP MODE
• I PULLED OVER AND RESTARTED THE ENGINE
• NO LIMP MODE - ALL NORMAL
• HEATER WORKED
• I CHECKED THE EXPANSION TANK - WATER WAS SLIGHTLY MURKY BUT LOOKED VERY NORMAL

My question is this:

1. How likely is it that my Oil cooler has failed?
2. How likely is it that my Head Gasket is buggered?

The next step will be to remove and replace the Oil Cooler I guess! Anything I can do without taking it to a garage that will help me diagnose between Head Gasket / Oil Cooler?

There was NO GUNK - just VERY black engine oil - the condensation on the tank looks like gunk but it is not!

The coolant tank looked like someone had put old engine oil directly into it - I initially worried the prospective buyer had tried to scam me (there were two of them and I didn't keep track of all their actions. I did some internet searches and it came up as a scam. The problem with this is that they never made an offer on the car. So it is unlikely that the two prospective buyers were out to scam me.

There is no Mayonnaise like substance inside the oil filler, it all looks really clean and normal.

The dipstick was slightly low but not worryingly low - it still met the marker requirements.

I located the lower coolant hose. I pulled off both radiator boost pipes first by mistake. A mechanic friend advised that this was the lower hose via picture confirmation on whats app and I pulled it off. The spring hose clamp was incredibly difficult to remove as it was pointing away from me. I used a combination of several pairs of pliers and some mole grips. I have seen online you can buy hose clamp pliers that are much better for the removal but they are expensive. I advise anyone doing this to get those or 90 degree needle nose pliers.

I got soaked in coolant. The coolant was pink which I initially thought meant it must have been someone pouring the oil in the expansion tank but soon accepted that the oil would likely rise to the highest point - the expansion tank. I am still unsure why my expansion tank is black oil and not brown sludge/chocolate milkshake looking though?

I am not sure if this step was advisable, I hooked up the garden hose to the out pipe that would connect to the expansion tank and flushed through the system.

This is how the expansion tank looked after removing, filling with Kerosene and shaking then reinstalling. I tried dishwasher tablets first and they did nothing. The kerosene made this effortless. I thoroughly rinsed with water after.

Healthier looking expansion tank.

Don't see any oil leaking from the oil cooler? Would I or would the oil just mix with coolant inside?

[cliffcoggin]

Connor.

Before buying any expensive, whether Audi or non-Audi, parts and trusting to luck that the problem will be solved, I would carry out some pressure tests to find where the problem really is.

A compression test should reveal if there is an internal engine leak, though one or more low cylinder pressures could be the result of worn rings, defective valves, or damaged head gasket. A pressure test of the oil cooler with water at mains pressure together with a valve and a dial pressure gauge will reveal if it has a hole.

Both tests can be done by the competent home mechanic with some ingenuity and cheap instruments. 

[connor_199]

Hi Cliff,

Thanks for the response to this - I really appreciate it!

Could you (or anyone else reading) provide a more in depth detailing of these tests? I have seen an oil cooler test on youtube involving a vacuum pump. I have also seen the opposite (blowing air into the cooler - but it seems this requires a compressor which I no longer have.

Any further information anyone can provide on the following would be amazing:

• Compression testing - AT HOME.
• Oil Cooler testing - AT HOME.

Links to how to's would be much appreciated, especially if it is specific to the 1.9 TDI Audi A3.

Thanks,

Kris.

[connor_199]

Something else I have noticed:

There is a patched section of the lower coolant hose about 6 (ish) inches long.

In the picture below you can see the join from the one end. It is very possible that this join was failing/leaking or that it is now failing as the pipe has been pulled off and put back on several times which would have created a tugging force at the joins.

I assume that the pipe had deteriorated (prior to my ownership) and was patched up using an additional piece of hose and some rubber glue? I imagine the process to be similar to a puncture repair on an inner-tube of a bicycle.

My speculations:

• The car may have had a coolant leak prior to my ownership from the lower hose
• The lack of coolant could have resulted in overheating - left un-noticed
• This may have inadvertently caused a crack somewhere in the head.
• This is all speculation - I still need to do a test on the oil cooler and pressure test.

[Magnet]

Hello Connor, 

I must applaud the attention to detail you have taken in describing the symptoms, and the way you have gone about the rectification procedure. 

I agree with Cliff regarding the usefulness of compression testing for certain symptoms, but in my book (apologies Cliff - and it’s only my opinion) I wouldn’t be going down that road at the moment. Compression testing is great for major gasket failure detection,  where the gasket has failed between say two adjacent cylinders, or to detect valve or piston issues, but seldom ‘minor’ oil/coolant mixing problems. 

If this were mine, I would be removing the oil cooler it’s it’s not too difficult - usually isn’t- and subjecting it to your flushing/ cleaning routine, before having it pressure tested. Automatic transmission specialists can normally do this. This could be the source of your issue, so needs to be eliminated/ confirmed before going further into anything else. If it prove to be serviceable, then I would then ( and only then) move on to getting the coolant system pressure tested. 

Perhaps you could let us know how you get on Connor.

Kind regards,

Gareth. 

[connor_199]

Hi Gareth,

Thank you for the compliment on detail. I am very methodical and obsessive when I have something on my mind worrying me!

I like the suggestion of taking off the oil cooler for diagnosis, I have seen a few videos on how to perform the test and believe I could probably find a way to do this at home. 

One question:

• Will I need to change oil after removing the oil cooler?

Regards,
Kris.

[connor_199]

I plan on removing the Oil Cooler and trying out this test (I will likely need to ask a garage to help as I don't have the kit):

https://www.youtube.com/watch?v=WNYx4Xjr8-I

 

[Magnet]

Hello Connor,

Speculation is fine, but in basic terms it’s no better than assumption , and as some wag once said ‘Assume’ translates to making an !Removed! (out of) u and me! 

Working on fact and basic logic generally pays dividends, whereas assumptions tend to lead you off at tangents. 

Again it’s great to be self-contained when carrying out jobs, but it boils down to the right tool for the job. If you don’t have it, then it’s best to employ the aid of specialists, unless buying the tool will be covered by a sufficient volume of future work. In this case - highly unlikely. Another benefit of going to the specialists with your oil cooler is the likely possibility of being able to pick experienced brains - always worth that little bit of outlay. 

If it were mine, I would be treating this as a one thing at a time job, and trying not to worry about the next stage until you need to. Was it Yogi bear who said ‘Worrying never did help none!’ 

Changing the oil when you get to the root cause of the problem? Most definitely - using only good quality oil and filters. For me - Quantum oil and Mann filters if not using VAG filters. 

Kind regards,

Gareth. 

The #Removed# bit is the first three letters of the word assume!! 

No one really wants to tell me why this great? editing system removes this for the example, but allows the abbreviated form of four letter words to sail through. 

[Judy C]

Does anyone know about how much this would cost to fix at a shop?

[Magnet]

Hello Judy,

Welcome, and thanks for joining. 
Pardon my ignorance on location abbreviations, but I’m guessing you are based in the States, by your description of ‘shop’ , as opposed to UK’s ‘garage’.
Bearing in mind that this is a pre-Covid thread, I think it would be difficult to guess at what this job would now cost in the U.K. - States??  Probably impossible to estimate, but I’m sure you will easily be able to obtain a couple of quotes to choose from. 
Sorry we cannot be more specific for you.

Kind regards,

Gareth.