Question for the mechanics about oil analysis

[sammyg2]

If a bearing had failed there should be a high concentration of lead, tin and zinc in the oil sample.

[Dansvan]

Iron, aluminum, chromium. All sounds like piston wearing on cylinder bore. Chromium is used in some piston rings, and in cheaper to produce catalytic converter substrates. The catalytic converter material is getting inside your engine.

[cabmandone]

Originally Posted by Dansvan

Iron, aluminum, chromium. All sounds like piston wearing on cylinder bore. Chromium is used in some piston rings, and in cheaper to produce catalytic converter substrates. The catalytic converter material is getting inside your engine.

Good call and can't be good on engine internals.

[javadog]

I’d like you guys to explain to me how the material from a damaged cat can get inside the crank case of an engine.

[cabmandone]

Originally Posted by javadog

I’d like you guys to explain to me how the material from a damaged cat can get inside the crank case of an engine.

When the cat collapses and the exhaust gas has nowhere to go but back through the engine, where do you think the dust particles of the cat would go?

I don't think your grasping that this cat collapsed on itself all at once plugging the exhaust off almost completely.

[javadog]

That’s not possible. If the cat plugged completely, the engine would stop immediately. As long as it was running, exhaust was flowing in only one direction through the cat. The flow may be substantially reduced but it is still moving in the same direction as normal.

Even if what you say is possible, and it is not, it still doesn’t get into the crankcase.

[cabmandone]

Originally Posted by javadog

That’s not possible. If the cat plugged completely, the engine would stop immediately. As long as it was running, exhaust was flowing in only one direction through the cat. The flow may be substantially reduced but it is still moving in the same direction as normal.

Even if what you say is possible, and it is not, it still doesn’t get into the crankcase.

Not true. It plugged completely once and it did indeed run. I'm telling you from experience. I'm not guessing. The engine shut off completely and black smoke belched out of the tailpipe when it happened the first time but then started and ran and yes the cat was completely plugged off.

How does silicone from a lack of filtration get into the crankcase?

[gtc]

Originally Posted by 1990C4S

I saw a turbo Thunderbird lose timing, and after driving the cat was cherry red...full retard maybe, causing uncombusted fuel to burn up in the cat?

Everyone knows you never go full retard.

[javadog]

Originally Posted by cabmando

Not true. It plugged completely once and it did indeed run. I'm telling you from experience. I'm not guessing. The engine shut off completely and black smoke belched out of the tailpipe when it happened the first time but then started and ran and yes the cat was completely plugged off.

How does silicone from a lack of filtration get into the crankcase?

OK, explain how an engine can run with no flow through the cat. Think about it, for a minute, before answering.

Silicon (no e on the end) can get into an engine in a bunch of different ways. What you are likely referring to is silicon from dust, which gets into the cylinders because of inadequate air filtration. Some small percentage of this gets in the crankcase via the blow-by gassed that get past the piston rings.

In any event, read this for more information on silicon in an engine oil analysis. It’s not always necessarily bad news.

https://www.blackstone-labs.com/the-silicon-bugaboo/?session-id=phmbg5zdv0qytab0tee3tj45&timeout=20&bslauth=&urlbase=https%3a%2f%2fwww.blackstone-labs.net%2fBstone%2f(S(phmbg5zdv0qytab0tee3tj45))% 2f

[Dansvan]

Originally Posted by javadog

I’d like you guys to explain to me how the material from a damaged cat can get inside the crank case of an engine.

The cat is built into the exhaust manifold. Very close to the exhaust valve. The variable valve timing strategy holds the exhaust valve open under certain conditions to allow exhaust back into the cylinder on the intake stroke to dilute the mixture thus reducing NoX. EGR without an EGR valve. The top of the cat substrate takes the most abuse and deteriorates. It is sucked back into the cylinder accelerating wear. The more wear, the more oil blows by and hits the cat substrate over heating it causing more damage and more material breaks off and ends up in the cylinder. Vicious cycle until it wears out. The cat substrate goes by the worn rings and cylinder bore as combustion blow by. This is real, it has happened to several manufacturers. Ever increasing emission demands require closer cats for faster light off. In order to
Keep costs down material corners get cut. Some aftermarket tuners (on Nissan I believe) have gained 50-70 hp just by changing the VVT strategies.

That’s the simple version. There’s obviously more to it. Exhaust reversion, sound (Pressure)waves, etc.

[cabmandone]

Originally Posted by javadog

OK, explain how an engine can run with no flow through the cat. Think about it, for a minute, before answering.

Silicon (no e on the end) can get into an engine in a bunch of different ways. What you are likely referring to is silicon from dust, which gets into the cylinders because of inadequate air filtration. Some small percentage of this gets in the crankcase via the blow-by gassed that get past the piston rings.

In any event, read this for more information on silicon in an engine oil analysis. It’s not always necessarily bad news.

https://www.blackstone-labs.com/the-silicon-bugaboo/?session-id=phmbg5zdv0qytab0tee3tj45&timeout=20&bslauth=&urlbase=https%3a%2f%2fwww.blackstone-labs.net%2fBstone%2f(S(phmbg5zdv0qytab0tee3tj45))% 2f

Hmm.. now how would fine dust from a failing cat end up in an oil sample?? I understand that silicon isn't necessarily from lack of filtration. Blackstone is who did my sample for me and we discussed the high level of silicon in the sample. The reason I asked about silicon from poor filtration is because it would enter the oil sample in the same way the silicon due to poor filtration would.

Read Dan's explanation.

As to the car not being able to run. Come on over and I'll show ya. Mind you that this time it didn't completely collapse as it did the last time. But as I pointed out, the complete collapse the previous time caused the engine to shutdown completely but it did start up and it did run with a plugged cat. And I'm done arguing this point. You should move on as well.

[1990C4S]

I believe Dansvan is correct, this is something I have read about before. All speculation, but I think it can happen. Google gives you lots of examples (all unverified).

The engine simply cannot run with a fully plugged cat. It can run with a partially plugged cat, so maybe we are just parsing words now. I doubt the cat was or is 100% blocked.

[1990C4S]

So this isn't a new thing...Maserati and Nissan seem to be pretty common culprits according to Google.

Here is some info:

https://www.motorweek.org/features/goss_garage/catalytic-converter-issues

[cabmandone]

The thing that I really can't wrap my mind around is why there were no codes in the ECU for emissions. Both times there weren't any codes for any issues when the cat failed. I'd think the upstream and downstream would have been way out of range which should have set a code and illuminated the CEL.

[1990C4S]

Maybe there was no error to display....

What if the cat simply failed and the debris went back into the engine causing serious damage?

Rereading your post from page 1, the clogged cat is speculation. I think it's an unlikely mode of failure. Lots of other events are more probable, and still lead down the same road.

I would like to see what the cylinder bores look like now...

[cabmandone]

Originally Posted by 1990C4S

Maybe there was no error to display....

What if the cat simply failed and the debris went back into the engine causing serious damage?

Rereading your post from page 1, the clogged cat is speculation. I think it's an unlikely mode of failure. Lots of other events are more probable, and still lead down the same road.

I would like to see what the cylinder bores look like now...

The clogged cat was confirmed. They replaced the cat. I'm hoping they will take the pan off and inspect the bottom end. I've also asked if they have a bore scope to check the cylinder walls.