What is this strange black fluid inside my engine

[DV0993]

Hi all,

A couple of elevated Lead readings on my used oil analysis have caused me to take the pan off to inspect and replace rod bearings.

In the process, I found some strange black fluid at the bottom of the pan and also in small amounts when cracking open rod bolts. It also smells strange and I catch a whiff of the smell with each rod.

Wondering if this could be liquified bearing overlay coming from the mains? Note: This has never been the colour of my motor oil - its jet black! See pic of it running down a journal after rotating crank with rod out of the way.

 

[PontiacHO]

Excessive fuel diluting the oil most likely. If this engine is operating with a constant high RPM driving style, has blowby, and-or never reaches proper temperature can cause similar results.

 

[Sandstorm]

The jet-black color and "strange" pungent smell are the classic signatures of Lead Sulfide (PbS) or Copper Sulfide (Cu_2S) formation.

 

[DV0993]

Thanks both - I did also have high fuel dilution in the last oil analyis.

Not to spin out this thread, but I also found (or caused) a scratch (finger nail catches) in the seemingly excellent condition crank.

I'm thinking of polishing on the scratch only; and leaving the rest of the crank alone - vehicle is a honda s2000

 

[Snagglefoot]

That’s a high rpm engine. What motor oil are you using?

 

[The_Jeff]

That first pic almost looks like plastigauge, like someone was trying to check clearances because they had the motor apart because... ?

They also used to use lead wire before plastigauge was invented.

But why didn't they get it all out of there? And how did that scratch get there?

Sorry to freak you out. Probably a more innocuous explanation.

 

[Cujet]

Given adequate care, you can polish that scratch out and get a great result. It is my belief you caused that scratch, and it has a raised section. Any raised bump like that will trash a bearing in short order. By the looks of the picture, I'd advise you to be significantly more careful. Keep metal parts away from each other, and keep them perfectly clean.

 

[DV0993]

Will do!!

 

[Cujet]

Will do!!

The S2000 is a magic little car with fantastic performance for a spirited driver. For a number of years I had a 2004 with the Inline-Pro Stage 1 turbo kit. I purchased the car that way, and it really needed help. While it made 407RWHP, all of it was between 7000 and 8000RPM. Pretty useless. It made near zero boost below 6000. And the turbo wastegate just dumped via a short tube on to the side of the block. Ugh, who does that?

After many hours of tweaking, welding a wastegate dump tube into the exhaust, and fixing the turbo kit's other issues, I made some headway with driveablity. But in the end I got tired of the ever present lag between shifts. Having built many turbo race engines, my S2000 would have been better off with a proper DIY turbo header (short, even and tight) and more responsive turbo hot section.

I eventually broke the differential due to torque loads, and the transmission failed due to lack of forward bearing lube (a known issue)

Post some pics of your car!

 

[DV0993]

Oh! Nice to hear from a former s2000 owner! Sounds like it was a lot of fun

I'll send some pictures on my way to work tomorrow - I have been losing sleep over that scratch after hearing about how it is near impossible to restore the factory crank due to its hardened coating.

Its nearly 2am here (literally losing sleep!) - I'll dig out some photos for you tomorrow!

 

[QwikKota]

Curious as to why you would tear into it instead of running a heavier oil or just leaving things alone? Not trying to kick you while you are down.

 

[maraakate]

Oh! Nice to hear from a former s2000 owner! Sounds like it was a lot of fun

I'll send some pictures on my way to work tomorrow - I have been losing sleep over that scratch after hearing about how it is near impossible to restore the factory crank due to its hardened coating.

Its nearly 2am here (literally losing sleep!) - I'll dig out some photos for you tomorrow!

Web Cam can do hard welding for cams and cranks. They do it a lot for those older Honda motorcycles that need reconditioned. May be something they can do for you, but you'll have to call: https://www.webcamshafts.com/

 

[DV0993]

Curious as to why you would tear into it instead of running a heavier oil or just leaving things alone? Not trying to kick you while you are down.

No I don't blame you for asking the question - was trying to do the right thing by the car.

High lead readings after multiple used oil analysis - Already running the thickest oil possible.

Save for user error causing the damage it would have been worthwhile.

 

[Cujet]

If you decide to repair that in place, I suggest filling the drilled passageway with a small cotton ball and grease. Assess the height (if any) by using a precision draw file technique (side to side), new ultra fine flat file, touching only the edges of the scratch. Then with the care and skill of a neurosurgeon, use a Dremel tool and ultra fine craytex wheel (hard rubber embedded with polishing compound) to polish the edges. Don't worry about the valley of the scratch just clean it out.

REMOVE the plug from the drilled passageway, clean inside the hole and of course around your work. Done correctly, it will be fine.

 

[QwikKota]

No I don't blame you for asking the question - was trying to do the right thing by the car.

High lead readings after multiple used oil analysis - Already running the thickest oil possible.

Save for user error causing the damage it would have been worthwhile.

Was the lead from an additive perhaps? Hopefully you can get rid of that scratch.

 

[DV0993]

If you decide to repair that in place, I suggest filling the drilled passageway with a small cotton ball and grease. Assess the height (if any) by using a precision draw file technique (side to side), new ultra fine flat file, touching only the edges of the scratch. Then with the care and skill of a neurosurgeon, use a Dremel tool and ultra fine craytex wheel (hard rubber embedded with polishing compound) to polish the edges. Don't worry about the valley of the scratch just clean it out.

REMOVE the plug from the drilled passageway, clean inside the hole and of course around your work. Done correctly, it will be fine.

Cujet, I'm very appreciative of your advice.

I'd like to run my plan by you and ask some follow up questions.

1. Block the oil feed hole with a "gun cleaning patch" covered in lithium grease - the intention is that the grease makes it stick.

2. Using the same lithium grease covered patches (cut to size) - isolate the work area (is this the idea behind the precision draw file technique?

Question - Method: Will the method you describe involve polishing using the edge of the dremel attachment horizontally along the scratch? My initial plan was to use the finest possible lubricated sandpaper over the scratch - rubbing vertically.

Question - Measure of success: It sounds like the goal is to take off the rough edges but leave the scratch visible (i.e it no longer catches on your finger) - is this correct?

 

[DV0993]

@Cujet

Pics as requested!

Only modifications are an engine torque damper, a few chassis braces, good coilovers and a greddy spectrum elite exhaust.
Its running a052s on the factory wheels

 

[Cujet]

Great looking car!!!


This was my beast. In many ways I wish I still had it. And had simply built a replacement turbo system myself. The basics were already there. At the time I was not feeling well and did not have my health issues well controlled.

 

[QwikKota]

Great looking car!!!


This was my beast. In many ways I wish I still had it. And had simply built a replacement turbo system myself. The basics were already there. At the time I was not feeling well and did not have my health issues well controlled.

Which platform are you using to host images? Not showing on my end.

 

[DV0993]

Update: I have now addressed the scratch and I am reasonably optimistic about the results.

It is less pronounced, still catches my finger a little (notably less) and I believe it has no high spots.

To check for high spots, I used and discarded two new honda bearings (including one "too thick") for the journal. I moved these (lubricated) bearings along the surface and inspected for scratches. The job was deemed a 'success' when the third (correct) bearing did not show scratches on the surface.

Lets hope the Honda gods look after me - I'm not sure if the journal can still tolerate track work, but my plan is:

- Oil sample at 300km and then normal intervals assuming all good.

- Pull the pan and inspect the lower bearing/journal at 5000km.

May keep it off the track until confirmation of the success of the repair at 5000km occurs. Across the spectrum of outcomes, the repair is a complete success, wear on the bearing is elevated or it fails within 10 minutes.

If anyone has any alternative thoughts to this plan they are most welcome.

Thank you again @Cujet