High Lead in 1.8T stroker Motor

[Kevin C]

The lab results on my 1.8T have me a bit concerned. After 25,000 miles on a new build I got a spike in lead that I don't have a good explanation for.

Engine: 1.8T stroker
320hp / 22 psi boost, street driven
Total Miles Since Build: 25,000
Bearing Types:
Mains: Factory Aluminum (polymer coated)
Rods ACL Tri-Metal performance (polymer coated)
Full floating pins (bronze bushed)
Forged crank - New OEM


Oil: Redline 5W40 High Zinc

This OCI 5000 Miles, 25,000 miles on the build - Redline 5W40 High Zinc

Metals:
Aluminum 6
Chromium 1
Iron 14
Copper 8
Lead 122
Tin 3
Molybdenum 364
Nickel 0
Manganese 1
Silver 0
Titanium 0
Potassium 4
Boron 45
Silicon 14
Sodium 13
Calcium 2811
Magnesium 46
Phosphorus 850
Zinc 1032
Barium 0

Previous Results OCI 5000 Miles, 20,000 miles on the build - Redline 5W40 High Zinc

Metals:
Aluminum 5
Chromium 0
Iron 8
Copper 4
Lead 0
Tin 3
Molybdenum 339
Nickel 0
Manganese 1
Silver 0
Titanium 0
Potassium 0
Boron 76
Silicon 14
Sodium 7
Calcium 2570
Magnesium 203
Phosphorus 1068
Zinc 1141
Barium 0

Previous Results OCI 5300 Miles, 10,900 miles on the build, Mobil 1 5W-40

Metals:
Aluminum 5
Chromium 1
Iron 22
Copper 9
Lead 1
Tin 0
Molybdenum 70
Nickel 0
Manganese 3
Silver 0
Titanium 0
Potassium 0
Boron 185
Silicon 14
Sodium 6
Calcium 2884
Magnesium 17
Phosphorus 873
Zinc 958
Barium 0

Unleaded fuel only.

During the last 5000 miles the motor had its valve cover gasket replaced and had developed a drip at the oil filter. The oil level never went under the add line.

Prior to switching to Redline I had been running Mobil 1 and had noticed copper glitter in the oil (the lab test showed 9ppm). I switched to Redline with the expectation that it would have better film strength. On the next change there were no visible signs of copper, it looked like everything was perfect.

The motor runs great, no knocking, still smooth and quiet.

Is it possible that the lead is leaching out of the trimetal bearings? I have heard that this can happen with certain synthetics but I'm surprised at the level and the sudden change, one oil change interval to the next.

Thanks,

Kevin C

 

[Jetronic]

I've seen elevated lead in other Red Line UOA (all from blackstone, I think), but not to this extend. I don't know if it's real or a false positive either. What I haven't seen is worn bearings from using Red Line.

 

[thastinger]

Is this your first run on Redline oil? Looks like the other samples were M1?

 

[Kevin C]

Is this your first run on Redline oil? Looks like the other samples were M1?

This is the second consecutive run on Redline, the first Redline run had 0 lead.

 

[JoelB]

I would sample again in something like 2k miles and see what you see. Could have picked up a particle streak.

 

[Cujet]

UOA results drive me crazy as this could be something/nothing or could be that someone mixed in a bit of leaded fuel.

Tri metal bearings have a face surface of (I think) Tin, Copper and Lead. An increase in one without an matched increase in the others makes me think it may not be real. But just a wild guess.

22 pounds boost is on the cusp of needing a 50 viscosity synthetic in many engines.

 

[wwillson]

I would pull another sample and send it to Wearcheck. When you get extreme results, it's better to get a second opinion.

 

[Rand]

looks like you possibly got some leaded fuel or used certain octane boosters etc.

So has it been 100% pump gas from regular gas stations and no gas additives?

Also consider the uoa might have been contaminated..

What vehicle is this?

 

[fantastic]

Just keep monitoring. Ask to re-test? Not sure it would change much. The Connecting rod does appear to be made of Pb.

 

[Trav]

As Cujet posted I would expect a rise in tin and copper coating the bearings before hitting the lead. On tip off though is you say there was copper glitter in the oil on a previous oil change. A standard UOA looks for PPM, larger particles are usually collected in the filter so it is very possible the bearings have an issue. My engine I would pull the caps and have a look see before damage to the crank occurs if everything okay the peace of mind is well worth it.

 

[930.engineering]

Mains: Factory Aluminum (polymer coated)
Rods ACL Tri-Metal performance (polymer coated)
Full floating pins (bronze bushed)

Lead 1

Lead 0

Lead 122

Unleaded fuel only.

I don't get it.
.

 

[himemsys]

Anything different about how you sampled? Could there have been lead introduced from a container you sampled into? Or did you sample straight from the sump to the sample container?

 

[JAG]

I would check the oil filter for metal particles. If it is metal can type, use a proper oil filter opener so you don’t introduce particles while cutting it open. If you don’t see particles with bare eyes, use a magnifier.

 

[twX]

Even though there isn't much tin or copper, the fact that you've already found bits of copper in the oil leads me to believe that the lead is probably from the rod bearings. You could contact ACL to see if they can give you some specifics about what each layer of the bearing is made of.

Cut the oil filter open and check it for metal. I wouldn't wait until the next oil change to do this.

I'm curious about what all went into stroking the engine. Generally, using a larger crankshaft will increase the minimum oil pressure requirement of the rod bearings at a given rpm. Another way to say this is that the maximum safe rpm for the rod bearings will be lower if the engine is stroked, all else being equal.

This is because the oil supply needs to overcome centrifugal forces, which increase with the distance between the rod journals and the centre line of the crank (and also with rpm). A higher oil flow rate could be required to keep the bearings cool enough as well. If the engine still has a stock oil pump, and the stock rev limit, you could be pushing the limits of the rod bearings. There's a good chance that the engine your stroker crank came from had a lower rev limit or a higher output oil pump.

 

[wpod]

The rod bearings are the only lead in the engine , any additives leaded gas added? The engine is a pretty high pressure engine with the larger displacement and the turbo boost. Do another UOA. All the above posts are spot on.

 

[Kevin C]

The car is a 2003 Audi A4. I have been keeping an eye on the copper because it seemed bit higher than I would expect.

I built a 1.8T using the block, crank and oil pump system from a 2.0TFSI to make what might be the only "1.8T " with a counter balance system to cancel second order vibrations. Basically, a 1.8T head on a 2.0TFSI block fitted with Mahle forged pistons and aftermarket forged rods.

The TFSI pump uses a dampened drive to protect the pump drive from crank vibrations caused by the fast pressure spike of the GDI combustion cycle. That drive has a bronze bushing that does bed in over time (fast pressure spikes are not an issue on my port injected mutt motor). Initially I was assuming that the dampened drive was just bedding in.

The TFSI pump has about 25% more capacity than the stock 1.8T pump and was designed to work with the crank I have. As part of the build the main bearing clearances were optimized using select fit bearings (this is a factory procedure that most builders skip).

I sampled directly from the oil stream when I did my last change.

I wish I had kept the filter.... I will be resampling once I hit 1000 miles on the new oil.

No known additives or leaded gas. The only work done was I changed the valve cover gasket. It's possible that some contamination got in the motor that could cause a bearing when I had the cover off. I do my best to keep in clean. An off the wall explanation could be the gas station got some leaded AV gas? I would bet that I'm having a bearing issue before I would believe that.

I am confused on the no lead for so long and then the sharp spike. My take was that if the copper source was the rod bearings then I should have seen lead all along. Keeping the same copper level with a spike in lead does not seem to make sense.

I really appreciate the input. I plan on taking another sample.

The bearing alloy is supposed to be mostly copper, I will try and get a confirmation from ACL.

ACL blurb on the bearings I am running: https://www.aclperformance.com.au/files/56469_race series info.pdf

I don't have a big issue with checking the rod bearings if I have to.

 

[Nathan]

Did you happen to run an octane booster that is *for offroad use only*?
I wonder if that might have lead in it.

 

[addyguy]

Leaded fuel or octane boosters sounds like the culprit on a highly-built turbo engine.

 

[Rand]

jumping from 1 to 100 lead you would have no bearing left?
might need to inspect for peace of mind..
If the last oci reported 100..
the new oil probably is at least 10 since some oil is left in engine.

 

[Kevin C]

Before commiting to a teardown I have been do a bit of research and managed to come up with a theory.

There are several layers to the Tri-Metal bearings.

First is the steel shell.

The next layer is a copper lead tin alloy When ACL specifics the tri metal alloy, the are calling out the thick 0.3mm layer (according to ACL 74% copper, 24% lead and 2% tin). After that layer there is a very thin nickel barrier layer 0.001mm. The top layer is called out as Lead, Copper Tin and is 0.013mm thick. The swapping of what alloy is listed first seems to indicate that the top layer is mostly lead.

I found a good writeup on trimetal top layer alloys, it looks like they are typically about 85% lead. That would explain the lead to copper ratio. I called the ACL tech support line to verify, they are getting confirmation from the factory engineers. That would explain the high lead to copper ratio.

The next question is why it happened? I have 25,000 miles on the motor without issue. It has seen some hard runs without any lead until this last checkup. That included a setup that was making more power than what I have right now. I did make one run where I held the motor at a higher RPM longer than the other tests.

One of a few possibilities:

1: The bearing are overloaded at max rpm / full throttle (clearance / film strength issues) and that hard run was enough to cause damage.
2: The bearings are starting to fatigue and shed lining.
3: Some type of oil starvation problem.

#1: Seems less likely, especially given that I dropped the peak power by 30hp
#2: This is what I think is going on, I will know when I tear it down.
#3: It's possible that a relief valve stuck, I will inspect them when I tear the motor down (Audi has two pressure relief valves and one filter bypass valve).

The short story is that the alloy that a trimetal bearing has riding on the crank is probably not what I thought it was. King Bearings has some great articles on this including a comparison to a competing trimetal bearing that sure seems like an ACL bearing.

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