Options to help a sick W12?

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I have a 2006 Phaeton W12 that's been giving me some persistent trouble with cam adjuster performance. Everything is fine when it's cold, but after it's well warmed-up and oil temperature reaches about 180F or more, they start having trouble performing consistently. One of them was replaced, along with its housing and control solenoid, and that didn't seem to cure the problem. As of late it's making some rapping sounds at RPM*0.5 that I really don't care for, also only when the oil is hot.

Oil pressure test results, OAT 57F. Current fill is dealer installed Castrol Edge Professional SLX 5w40, plus a quart of MMO added for troubleshooting. OCI is 10K with about 8K on this fill.

Cold start, idle: 68 PSI
Cold start, 1500 RPM: 70 PSI
Cold start, 2500 RPM: 72 PSI

Oil 150F, idle: 21 PSI (meh)
Oil 150F, 1500 RPM: 54 PSI
Oil 150F, 2500 RPM: 69 PSI

Oil 210F, idle: 12 PSI (very meh)
Oil 210F, 1500 RPM: 35 PSI
Oil 210F, 2500 RPM: 64 PSI

The pump consistently bypasses above 70PSI. VW lists a pressure spec of 3.0 to 4.5 bar at 2000 RPM with oil temperature of 80C. I didn't have that spec in-hand at the time I tested, but reading between some lines I suspect I'm okay or close to it. VW does not directly list an idle RPM spec, but 12PSI seems kind of sad. Almost all my troubles are at low RPM.

The top end of the engine is beautiful. No build-up or even varnish. My next task is to pull the oil pan off and see what there is to see. I **may** be able to pull the oil pump and inspect... repair manual says I can't without pulling the engine, but I don't see what's stopping me. I can definitely pull the pickup tube. It's extremely unlikely I can get access to main or rod bearings without dropping the engine, which isn't possible in the immediate future.

When I refill, what do you think I should refill with? It calls for a 5w40 oil meeting VW 502.00. My current thinking is Redline 0w40 or even 5w40. In addition to meeting spec, they have unusually high HTHS and kinematic viscosity @ 100C. Both of those things appeal to me right now.

Jason
 
That MMO thinned it out.

The rapping and low pressure would worry me, big time! It's clear, that when you're above 180F, you're experiencing the effects of low pressure.

I would drain and refill right now. Does Redline meet spec?
 
Originally Posted By: Astro14
That MMO thinned it out.

I don't actually have test results before the MMO, but the problem existed before the MMO. Also, bear in mind this is a ~13qt sump with only 1qt of MMO. It was added as a diagnostic measure, to help clean up anything that might be blocking an oil passage. Grasping at straws, since this engine seems very clean otherwise, but it was easy to try. This is the only time it's ever had MMO and it won't be in the fill going forward.

Originally Posted By: Astro14
I would drain and refill right now. Does Redline meet spec?

Yes, although I'm unclear what would be different between current VW 502.00 and 502.00-97.

Redline 0w40:

VW/Audi 502.00-97
VW/Audi 503.01-00

ACEA Service Class A3 B3/B4
API Service Class SN/SM/SL/CF
SAE Viscosity Grade (Motor Oil) 0W40
Vis @ 100°C, cSt 15.4
Vis @ 40°C, cSt 86
Viscosity Index 190
CCS Viscosity, Poise, @ °C 57@-35
Pour Point, °C -60
Pour Point, °F -76
NOACK Evaporation Loss,1hr @ 482°F (250°C), % 9
HTHS Vis, cP @150°C, ASTM D4741 4.0

Redline 5w40:

VW 500.00
VW 501.01
VW 502.00
VW 503.01
VW 505.00-97
VW 505.01-99

ACEA Service Class A3 B3/B4
API Service Class SN/SM/SL/CF
SAE Viscosity Grade (Motor Oil) 5W40
Vis @ 100°C, cSt 15.6
Vis @ 40°C, cSt 97
Viscosity Index 174
CCS Viscosity, Poise, @ °C 58@-30
Pour Point, °C -45
Pour Point, °F -49
NOACK Evaporation Loss,1hr @ 482°F (250°C), % 6
HTHS Vis, cP @150°C, ASTM D4741 4.4
 
No useful input, but very cool car. I'm jealous. I hope it doesn't have a major issue.

robert
 
This is such a rare bird that finding a shop that really knows it would be very difficult.
Is this a top end noise?
If so, could the problem be worn cam bearings, or at least excessive wear of the bearing surfaces machined into the heads, since I'd doubt that replaceable cam bearings were used?
It sounds like you're leaking excess oil from some heavily loaded surfaces somewhere, which is causing loss of oil pressure at revs too low for the pump to make it up.
I may be way off the mark, but unless the oil pump itself is actually badly worn, I'd think that it has to be either the crank or the cam bearings.
If you could find a shop that really knows these engines, which would exclude any VW dealer in SW Ohio, they could probably tell you what the problem is in a quick conversation.
Have you tried VW boards?
 
Maybe step up to a 50 grade for an experiment... m1 15w50 or similar. The "only when hot ..." suggests a loss of oil pressure somewhere... try cheap first, then go digging.
 
Those are both on the heavy side of a 40...so they should help your issue...

I was going to suggest my favorite, M1 0W40, which I use with great results, in the V-12. But it's a lot lower viscosity at 100C.

You might also consider changing more often than specified, to prevent it from declining in viscosity. I would also recommend a UOA, to see how the oil that was in there performed. An important detail.
 
Originally Posted By: robertcope
No useful input, but very cool car. I'm jealous. I hope it doesn't have a major issue.

Originally Posted By: fdcg27
This is such a rare bird that finding a shop that really knows it would be very difficult.

Thank you. I hope it doesn't have a major issue either. Rare is a bit of an understatement. My 2006, the last year Volkswagen imported them, has a newer variant of the W12 engine than the 2004 and 2005 models. It puts out 444HP, an upgrade of 30HP over the older variants. There were only twenty five (25) of them imported into the USA. So, used engines will be somewhat challenging to find.
wink.gif


Jim and Bill at Fairfield VW dropped the engine to replace one of the cam adjusters and its control housing and solenoids. I can't say they were experienced with this engine, for obvious reasons, but they were highly skilled and I was impressed with their work. I know a lot about the car so I was closely involved, and we had a good team going between myself, the service manager Stacey, Jim and Bill working on the car, and backing from the VW tech line. Got a lot of good pictures.

Unfortunately it didn't fully fix the problem, or it didn't stay fixed. I've actually been trying to figure out this cam adjuster issue, on and off, for the last couple of years -- 40K miles or more. It's not that severe, and it's not gotten dramatically worse over time, so I have hope of finding a solution that will let me keep driving it through its normal service life.

Jason
 
Originally Posted By: fdcg27
Is this a top end noise?

I'm not sure... it's a real booger to localize. It's much more recent than the cam adjuster thing, only been happening the last few months. Given the RPM*0.5 frequency, it's either top-end or combustion-triggered bottom-end. I lean toward bottom-end because it almost entirely disappears under load, and I don't see how that can be top-end. It's really only audible in Park or Neutral, and almost entirely disappears when I put it in gear. Again, it's only audible when the engine and oil are really fully heated up, not just the inner coolant loop.



Originally Posted By: fdcg27
If so, could the problem be worn cam bearings, or at least excessive wear of the bearing surfaces machined into the heads, since I'd doubt that replaceable cam bearings were used? It sounds like you're leaking excess oil from some heavily loaded surfaces somewhere, which is causing loss of oil pressure at revs too low for the pump to make it up.
I may be way off the mark, but unless the oil pump itself is actually badly worn, I'd think that it has to be either the crank or the cam bearings.

I agree with that, in principle. There has to be a reason, and those are the possible reasons. The cylinder heads are basically tweaked VR6 heads with serviceable bearings, and parts availability is good if needed. The bottom end is another story. There are no parts, there are no service procedures, no torque specs, no tightening sequences. It's an absolute work of art the way it's put together, but it's untouchable by design. When I pull the oil pan, I'm going to try to sneak a borescope up there and look around, but I'm unsure how far I'll get.

Originally Posted By: fdcg27
If you could find a shop that really knows these engines, which would exclude any VW dealer in SW Ohio, they could probably tell you what the problem is in a quick conversation. Have you tried VW boards?

Yeah. I am in touch with some trusted people who know things. But now that I've come upon lower oil pressure than I'd like to see, I wanted to loop in some oil people. So, here I am.
smile.gif


Jason
 
Originally Posted By: geeman789
Maybe step up to a 50 grade for an experiment... m1 15w50 or similar. The "only when hot ..." suggests a loss of oil pressure somewhere... try cheap first, then go digging

It's crossed my mind, but I'm given to understand the heavy stuff tends to come with chemistry and additive changes appropriate for older cars. I don't know if I would run into any trouble with metal or seal compatibility, or trouble with poisoning my catalytic converters. I'm not saying it's a problem, I'm saying I don't know.

I'm not trying to be a Redline fanboy, I've never even used it before, but going by spec sheets it seems perfectly tailored to my specific situation: engineered to meet VW 502.00 plus a couple of nice kickers at high temperature where I'm having trouble. I'm not an expert though so I wanted to run that past some people who are.

Jason
 
Originally Posted By: Astro14
If it really is low pressure, how hard is to replace the oil pump on this engine?

That's a very good question. I don't know.

On the older BAP W12, the factory repair manual calls out a reasonably easy process where you mainly just pull the lower oil pan. On the revised BRP W12, long story short, the factory repair manual says you have to pull the engine. The upper and lower oil pan designs were revised a bit, but not THAT much, and it's the exact same oil pump in the exact same location. So, either the manual is wrong, or there's a nasty surprise awaiting me when I open her up. Waiting on replacement fluids and correct sealants to show up first.

Jason
 
Originally Posted By: jyoung8607
Originally Posted By: geeman789
Maybe step up to a 50 grade for an experiment... m1 15w50 or similar. The "only when hot ..." suggests a loss of oil pressure somewhere... try cheap first, then go digging

It's crossed my mind, but I'm given to understand the heavy stuff tends to come with chemistry and additive changes appropriate for older cars. I don't know if I would run into any trouble with metal or seal compatibility, or trouble with poisoning my catalytic converters. I'm not saying it's a problem, I'm saying I don't know.

I'm not trying to be a Redline fanboy, I've never even used it before, but going by spec sheets it seems perfectly tailored to my specific situation: engineered to meet VW 502.00 plus a couple of nice kickers at high temperature where I'm having trouble. I'm not an expert though so I wanted to run that past some people who are.

Jason


I think that your Redline choice is a good one, you're going for the higher numbers at 100C, and it's at 85C (roughly, you said 180F) where the problem manifests itself.

The risk of poisoning a cat, or worse, O2 sensor, depends on how much is getting past the rings and valve stem seals. If your consumption is low, say 1Qt every 3,000 or better, then the risk of poisoning is equally low. The manufacturers want us the believe that 1Qt per thousand is "normal"... And at that level, you might have a risk.
 
If you suspect a bottom end problem, which based upon what you've posted seems very possible, I'd be inclined to remove that oil pump if it turns out to be as simple as you think it might be.
That would be the least costly possible failure point.
Everything else gets into $$$ and you've already been there and done that with a repair requirng engine removal.
If the oil pump measures just fine after you remove it, a thicker oil might then be a good choice, although you'd only be delaying the inevitable.
I'd consider M1 15W-50. Its cheap and readily available, unlike Red Line and doesn't have an additive pack that should cause your car any harm.
It would be worth a try in the warmer days we're suddenly seeing.
If it cures the noise, then you'll know that you probably have excessive bearing clearances and you can decide whether you want to go to the expense of having the engine hauled yet again to replace the mains or you just want to run it on a thicker oil until it spins a bearing.
From what you've posted, there isn't much published guidance out there for a field overhaul.
Good luck with your rare bird and keep us posted on what you learn.
 
I'm with fdcg27 - if your oil is the correct viscosity, then oil pressure dropping too much when hot is generally: excess bearing clearance or a worn oil pump.

So, from cheap to crazy (or from simplest to complex): change oil. replace pump, replace bearings.

But start with the oil change and see what that buys you. It's my opinion that the MMO reduces viscosity a bit, so just getting it out of there will help. The higher viscosity of either Redline oil should help. If the problem goes away, then you're set, otherwise, I would proceed with the pump next.

By the way, 12 cylinder engines are a work of art. Yours is particularly interesting. It's unfortunate that it's so rare, and not supported well. The V-12 in my car has quite a cult following and was built in reasonable numbers. Thanks to BITOG, I've found the right oil for it, and it runs just great.

There's nothing like a 12!
 
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Sometimes the oil pump doesn't fail, the pickup screen just has garbage in it, slowing down the flow of oil.

Of course, if you see that much stuff in the oil pan pickup, you would have to find what else has gone wrong in the engine.
 
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