High Lead in 1.8T stroker Motor

[Kevin C]

What does 122 pmm of lead mean? As a reality check I worked it out. My understanding is the the PPM is mass based (not volume).

Given that:

The engine holds 4.5 quarts or 4257ml. If the density is .866 g/ml I have 3686.6 grams of oil. If the lead is at 122 ppm, then there is at least 0.45 grams of lead missing from the rod bearings. Lead has a density of 11.43 grams per cc.

11.34*X = 0.45, X = .0397 cc's or 3.9 mm^3

There are four bearing sets that are about 18.8mm wide and they are about 48mm in diameter.

The surface area of one bearing is:

3.14*D*Width, 3.14*48*18.8= 2833mm^2

Four bearings: 11334mm^2

How thick a layer do I need to remove to account for 3.9mm^3 of lead in the oil? Assuming that all surfaces eroded evenly (I know that's not going to happen but I'm just trying to get an understanding of magnitude).

I get 0.000344mm. ACL says that the top layer is 0.013 thick. So its possible to get a 122 ppm reading and not have a large increase in clearance.

What happens if it was just one bearing and half of what was lost off of the bearing got trapped by the filter?

Now we have 7.8 mm^3 of lead missing from one bearing. That's a .0028 mm thick layer, so the shell would still have a 0.0102mm of lining left before the crank hits the nickel barrier layer that is behind the top surface.

The running clearance would have changed .0001".

My take is the I need to swap the bearings out, they are used up. I will inspect the rest of the engine, while I have it out and make a few minor upgrades.

King Bearings has a lot of good information of what fatigued bearings look like and what might be happening to mine.

 

[Pablo]

I love your graphics and your work, I would almost say you are overthinking it, but you aren't and that would be trite.

I will just state - and it was tangentially brought up earlier - you are likely 100% correct on where the lead is coming from, but it probably was doing this to some much lesser degree all along. But different oils will carry lead to be detected in a simple UOA much better than other oils. Redline seems to have this ability. The assumption here seems to be Pb is in solution. It isn't. Certainly this does NOT explain why the first run showed zero lead though! It definitely spiked up.

Maybe run a different oil, see what happens, I mean if you are going to tear into the engine aanyway.

 

[SubieRubyRoo]

Im gonna make a recommendation just before things get really crazy. Take another sample, and send it to a REPUTABLE lab. Not only has Blackstone made themselves infamous for questionable ppm counts, they are also pretty notorious for mixing up reports between customers.

Send off a sample to WearCheck in NC of your current oil. If it’s got elevated lead then at least you’re not tearing the engine down only to determine that everything was absolutely fine. The $35 for WC is a mere pittance compared to the time, energy & expense of an unneeded disassembly of an engine. JM2C…

 

[kschachn]

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 oil isn't going to cause that. Mobil 1 isn't going to generate "copper glitter".

 

[Kevin C]

The oil isn't going to cause that. Mobil 1 isn't going to generate "copper glitter".

In general I agree. That said I was pointing out correlation and as we know that does not determine causation.

The reason for the changes was that Redline has a higher 100°C viscosity (double check but it should be 15.6 cst, VS Mobil 1 5W-40 at 13.2. The intention was to get use an oil that should have a higher film strength at temperature.

The other option was to go to an XW-50 oil. For this run I went with 5W-40 but one that was at the higher end of the range.

I agree that on a sample of 1 there is no way to determine causation (or draw a conclusion), that said there was an observable change.

One follow-up note, I did take a look at what was left in my drain pan and found tiny fleck of a bearing material with a low melting point. I seperated a couple of them out using a microscope and I was able to melt them using a soldering iron.

 

[Nathan]

Detonation has a way of hammering bearings. If oil pressure is/was good, perhaps look at your injectors for cylinder to cylinder evenness and check the plugs for peppering. I like to put the highest flowing injector in hole #3 (usually the hottest) on a 4 banger.

 

[Kevin C]

Detonation has a way of hammering bearings. If oil pressure is/was good, perhaps look at your injectors for cylinder to cylinder evenness and check the plugs for peppering. I like to put the highest flowing injector in hole #3 (usually the hottest) on a 4 banger.

A very good point. I did get confirmation from ACL that that the top bearing layer is about 85% lead (they were very responsive to my questions). I have have started to order the long lead parts (Cometic head gasket is one) and I will keep an eye on the metal levels. Plug inspection will be on the weekend.

The tin levels don't quite match up so I will follow up with a test from another lab and a filter inspection.

The tear down looks to be a over the holidays project.

I apricate the help and good suggestion from everyone.