3B Coupe conversion update...

[archiboy24]

As most of you know, I'm near the end of my e//S2 conversion but have been struggling to try to solve a foaming oil problem of late. Today I replaced the 1.8 bar oil pressure sender, de-skinning every one of my knuckles in the process. Also removed and inspected the oil pressure relief valve, which looked fine and wasn't seized or installed incorrectly.
I then started taking a closer look at the turbo, pulling off the intake hose from the cold side. To my surprise, the turbo does not spin freely by hand. It turns, but does not spin. I can turn it with one finger on the blades, but there's resistance there. Aren't turbos supposed to spin freely? There is zero end-to-end or side-to-side play in the shaft. I first noticed this condition when I tore the engine down and rebuilt it. But I figured that it was a little tight because it hadn't had oil in it for a couple of years. However, now that the engine has run and oil has (presumably) circulated, one would think that the turbo bearings would be lubricated enough to spin freely. Could this resistance be blocking the flow of oil into and out of the turbo? Could this be causing the foaming oil in the oil pan? My gut feeling says yes. So I spent the rest of my day removing the turbo (I love undoing what took hours to do) so I could open it up and see if I can see a blockage of some sort. I also noticed when I was removing the turbo that there was less than about 1/4 teaspoon of oil that came out of the turbo and it's oil feed and return lines, which I found to be quite strange. The 1.5 liters of coolant that spewed out of the coolant return line more than made up for it though. Makes for a nice, greasy garage floor.
Anyway, what do you guys think? Does this sound plausible?

[SteveH]

The turbo shaft should turn without restriction if it's OK. You should expect some resistance from the cold oil, but not enough to prevent you from turning it with your finger. It wont spin round after you give it a nudge with your finger because of the oil drag on the bearing. I also wouldn't expect much oil to be in the bearing housing or return pipe, this would have drained out by the time the engine has cooled.

My only suggestion on this problem would be a leak on the pickup side of the oil pump or the pump itself. Is it a new pump? If air was being drawn into the oil stream it could possibly cause bubbles. Have you replaced or stripped any other parts of the lubrication system during your rebuild? If so, what parts/gaskets were replaced?

[archiboy24]

Originally posted by SteveH
My only suggestion on this problem would be a leak on the pickup side of the oil pump or the pump itself. Is it a new pump? If air was being drawn into the oil stream it could possibly cause bubbles. Have you replaced or stripped any other parts of the lubrication system during your rebuild? If so, what parts/gaskets were replaced?

I've replaced all the seals and gaskets on the engine, including new head gasket, and new crank seals and oil pump seal and oil pick up seal. I've checked the oil pickup, checked it again and re-checked it! It's not clogged and it is sealed properly. The previous owner said he never had oil problems at all. It has a new oil filter housing and new o-rings for the oil cooler lines. I'm really quite stumped!

[Doug_RS2]

I was speaking to my dad about priming my car as it had all the oil out of it and sump of etc. He asked If I had filled the oil pump with vaseline (iirc) as in his day, this was a common thing to do with oil pumps that were new.

Where are you getting the foaming abou? Are your cams covered in oil after starting?

What grade of oil are you using?

Have you disconnected an oil line to the turbo and turned the engine over(with the cam sensor disconnected) to see if oil gets pumped out?

When I turneed my engine over to build up oil pressure(with cam sensor disconnected), I had to turn it over for about 15 seconds before the pressure guage jumped up.

I think I am right in saying that the 4.5litres oil is for a service oil change - there is a lot more oil in the system if it has all been drained.

Have you got the correct dipstick in the car?

[archiboy24]

Originally posted by Doug_RS2
I was speaking to my dad about priming my car as it had all the oil out of it and sump of etc. He asked If I had filled the oil pump with vaseline (iirc) as in his day, this was a common thing to do with oil pumps that were new.

I did pack the oil pump with white assembly grease prior to priming.

Where are you getting the foaming abou? Are your cams covered in oil after starting?

The foam is only apparent on the end of the dipstick. The plastic baffle under the oil filler cap prevents me from seeing any oil on the cams.

What grade of oil are you using?

Castrol GTX 10w-40

Have you disconnected an oil line to the turbo and turned the engine over(with the cam sensor disconnected) to see if oil gets pumped out?

Not yet, but that's a good idea!

When I turneed my engine over to build up oil pressure(with cam sensor disconnected), I had to turn it over for about 15 seconds before the pressure guage jumped up.

I did the same. Spark plugs were out and pressure built to just over 2.0 bar.

Have you got the correct dipstick in the car?

Yes, correct dipstick.

[Doug_RS2]

You can remove that plastic baffle - then run the car - the cams should have a visible sign of oil over them when running.

2.0 Bar ?? Mmm - mine jumped upto 5 Bar IIRC - I can test this again to see if just turning the engine on the starter is enough to produce 5 bar - I'll try and do that tonight.

Do you think your assembly grease could be causing the foaming? You could try whisking some with oil to see if it foams?

[Stick Insect]

I don't like the sound of the grease. I like Doug's suggestion about the whisk test.

The reason thet oil pumps were packed with petroleum Jelly was so that it would prime the pump move easily once the pump was running and then mix well with the oil. Grease does not mix well with oil strangeley enough.

Archiboy what is the grease, is it mineral based or is it silicone? From the sound of it the only unknown factor in the build is this grease. You could drop the oil, leaving it to drain overnight and try a fresh load.

David.

[archiboy24]

I had a feeling you guys might comment on the grease! I should have mentioned that the foaming was occuring before I packed the pump with grease. At one point, I thought the foam was being caused by an improperly primed oil pump (pumping air instead of oil). So I removed the oil pan (sump?) and the oil pickup tube and then packed the pump with the grease (which was recommended by a very reputable Audi mechanic). I then followed the proper procedures for priming the pump, but to no avail. So the grease is definitely not causing the foaming.

[Doug_RS2]

I turned over my car again tonight with out it firing to see what pressure the oil pump would pump to - it took a few turns - 4 or 5 and then it went to 2 bar, next turn 4 bar, next turn 4.5 Bar and stayed at that. Is yours similar?

[archiboy24]

Did you keep the sparkplugs in? I don't recall exactly how mine behaved with the plugs in, but when I cranked it over with the plugs removed, I'm pretty sure it only went slightly past 2.0 bar. However, it got there fairly quickly - maybe after only a couple of turns. But then again, the engine cranks much more quickly and easily without any compression. I'll try cranking it over again with the plugs in it once I reinstall the turbo and have everything back together, which should be this weekend. If it only goes to 2.0 again, maybe I should suspect the oil pump after all.

[Doug_RS2]

I did it with the spark plugs out.

[archiboy24]

Hmmm. Interesting. I would like to see results from an engine that is known to be working properly. It could be that your oil pressure is abnormally high (thus producing the blow-by through the filler cap). On the other hand, my oil pressure could be abnormally low. It's all so confusing! I just want to drive my bloody car!

[Doug_RS2]

When the car is running the pressure is at 4.5 to 5 bar when oil is cold and just below 2 Bar when it is warm.

It looks like your pump is not pumping properly.

[archiboy24]

When mine is running, the gauge also reads 4.5 - 5.0 bar, which is normal at start up. I've never had it running long enough for the pressure to drop down though.

[Audilard]

Originally posted by archiboy24
It's all so confusing! I just want to drive my bloody car!

I can't even begin to imagine the anxiety you must be experiencing. I only hope I don't have to experience this when I get to that point....but I'm sure I'll have to deal with something!