How much metal is ok in your engine oil?

subaru335i said:

Yeah I wouldn't just pretend you didn't see the metal and try to run it. You MIGHT make it through the track day but it will absolutely do wayyy more damage and end up way more expensive than if you figure it out and fix it now.
An ounce of prevention is worth a pound of cure.
In this case you are trying to prevent outright block/crank/rods/pistons/heads destruction instead of maybe just needing a minor bearing/lifter rebuild.

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He’s right! The same thing happened to me during some dyno tuning last January. A lifter collapsed and during the troubleshooting we decided to send the oil to blackstone and it showed excessive wear mostly from the bearings.

Luckily for me the block, heads, crank and rods were in really good shape and the wiseco pistons were good enough to be reused, but we decided to swap those out for the more robust Diamond S2K option. The main work needed was new looser bearings. The bearings were apparently built with to tight clearances for the stress the motor was under, so it was determined by the engine builder to do it his way. Furthermore, the block was cleaned and re-honed for the new pistons and I got all new lifters and a new oil pump because it was unsure if metal got in these parts and we did not want to send metal through a refreshed engine.

This repair set me back about 7.5k (not cheap) for the tear down and parts and labor, but it could have been a lot worse if we carried on and not address the issue.

More than likely this is the route you will likely have to go in a best case scenario if you stop now. As a first step you should send the oil out for analysis and that will give you clearer idea of your engine health before removing the engine.

Sometime in the next few weeks, after my lift goes from "two hunks of steel laying on their side in my shop" to "a functional two post lift", I'll set to work on a diagnostic path.

Any guidance on what that might look like? To my way of thinking, motor should probably just come on out. Even if I found a smoking gun lifter, for example, wouldn't I be best served to go ahead check the rest of the motor? Taking that assumption (that motor is coming out) a step further:

What parts need to be upgraded assuming I don't desire to go much down the rabbit hole of modifying. Or said another way, what parts would I be stupid not to upgrade while motor is out, even if they're upgraded well beyond what's required at stock power levels? Car may end up getting thrown around a road course a few times a year, otherwise just a weekend toy. Will probably look at a mild cam if mine is screwed, lifters/pushrods/valve springs/etc that come along with a "proper" cam swap, but lets say there's no evidence that I have any issues beyond that, can I just leave bottom end buttoned up? If so, back to my first question: Do I really need to pull the motor? Or can I perhaps get away with pulling heads, visually inspecting cylinder walls, etc.?

I'm torn on what to do next, in case my rambling doesn't convey that. I'm also in mourning. This discovery led to a cancelled weekend at VIR, and an added budget line-item that I'm not thrilled about and the wife is really not thrilled about.

I'm not nearly the expert as others here, but I would pull the spark plugs first and use a $20 bore scope off Amazon to look for any obvious damage to pistons or cylinder wall scoring.

Then, if that looks good in each cylinder, I'd pull the blower, valley cover and rocker arms: you'll be able to see some of the cam lobes that way and inspect the valves / springs / retainers for any obvious damage or broken parts. Again, use the bore scope and/or a flashlight to make sure every cam lobe is healthy, less you have a collapsed lifter. You could also check lash on each valve while you're here to again look for any excessive lash (wiggly rocker arm) that might suggest a failed lifter.

If that all looks amazing, I might just put it back together.

But if you're really a glutton for punishment, the next step would be to pull the motor, drop the oil pan and then start checking the mains for abnormal wear: I'd pull the #1 main cap and if it isn't absolutely destroyed (think pot-holes on a road), I'd retorque it and again probably just put everything back together.

If the main looks really ugly, then start planning your rebuild. Generally, you'll need to deck / hone the block, finish hone the cylinders, clean the block, replace all main, rod and cam bearings, and deck the heads. You'll naturally want to have the valve seats redressed and replace or upgrade the valves, springs and retainers. I think that's the bare minimum.

But "while you're in there..." and don't forget changing higher mile engine accessories (water pump, etc) while everything is out. And...