Potential Cause of rumored GR86’s blown engine? Seal packing(RTV) was peeled off

[Tcoat]

Originally Posted by CincyJohn

Could someone explain to me a few things regarding these pics/failures?

One, why do they all look like a coiled snake? Shouldn't they look like small and medium bits of random crap? I mean, I guess I can imagine that a HUGE bead would create overflow beads on both the inside and outside of the pan and that eventually it just all comes off at one time together (or slowly, over time, gets sucked into the intake in one piece). But in that case, shouldn't the tech see the excess on the outside of the pan and flag it?

So, are these cases where the robot puts the bead too far to the inside of the pan making the overflow bead almost entirely on the inside?

Second, why wouldn't the other four sides of the strainer provide enough flow to prevent catastrophic engine failure? Is it a case where 90% of the flow comes through the bottom/top of the strainer?

The ridge where the pan sits will push any excess in more than out.


That stuff is actually very strong once set. if applied in a long section it will stay long so the "snake" if exactly what would be expected.

The strainer is meant to draw oil from all 5 sides but the main part is of course the center. Keep in mind that you don't have to complete eliminate the floe to cause issues just drop it below the critical level. Even just blocking the center and reducing flow by 60% (an out of my ass guess) could be enough to starve a bearing and send it spinning.

[Tcoat]

Originally Posted by NoHaveMSG

Or too much. In the case of the oil pan if the bead is squished out the whole chunk drops into the oil pan without getting chewed up by any moving parts. Here’s a crappy FIPG job done by a Toyota tech who “doesn’t build crap engines.”

…he built a crap engine.

Ya that picture shows pretty clearly how the ridge will concentrate and then chop off any excessive or poorly placed sealant.

[Ultramaroon]

Originally Posted by FrickingReallySlow

Bathtub failure curve baby

^^^this^^^

Dump me now, or love me long time.

[NoHaveMSG]

Originally Posted by Tcoat

Ya that picture shows pretty clearly how the ridge will concentrate and then chop off any excessive or poorly placed sealant.

My favorite example is the “cam lobe tickler.”

[Tcoat]

Originally Posted by NoHaveMSG

My favorite example is the “cam lobe tickler.”

Oh that is a rare one. Usually only found in vending machines in dive bar washrooms.

[DocWalt]

I was due for an oil change so I poked my crappy old borescope in the pan. Plenty of excess RTV. Not as bad as that above example from the Toyota tech, but still.

Subaru is in for a rude awakening in the next year, going to be a lot of pissed off people needing new engines. How the heck did the factory fail this badly?

[Spektyr]

Originally Posted by toeout

I did not track it, but did autocross it regularly. It saw a lot of rev limit time, but that should 100% be in the engine use parameters.

In a stock engine with stock tune, the owners only responsibility should be to keep the oil and coolant levels in check and I was very careful about that.

Just my 2c - but I didn't read the question about tracking as an admonishment. As a fellow GR86 owner the same question occurred to me simply as a "how does their driving compare to mine" kind of thing. It's natural to assume that the harder it's driven the sooner the problems appear.

Maybe if it's sped up by driving hard it's slowed down by driving less. Part of me thinks the smart move is to flog it and try to get it to fail quickly so you get on the list for a new short block sooner, and part of me thinks the smart move is to keep the miles low and drive nicely so you get in on the (probable) recall repair and have the car OOC for a couple days instead of weeks/months.

The biggest difference between the two for me is just having to deal with another break-in period.

Oh, and to the question about why the bead comes off as one long snake - that's a function of the way the material is shaped. When you squish too-large a bead of sealant between two flat surfaces and create that rope/snake on the inside edge the weakest point is where it meets the part of itself that's squeezed between the two surfaces. You have a sealant gasket between those two parts that prevents leaking, and then you have fat bead attached to the inner edge that has a lot more strength and surface area than the rest. As fluid moves past it there's a small amount of force applied. If there's enough movement, or enough "rope" surface area to create enough force to begin to pull it away from the thinner "gasket" part of itself you begin to multiply the problem. A gap appears and that rope not has even more surface area and can be pulled into the deeper parts of the fluid current where there's more flowrate. This pulls more of the rope away from the gasket, which creates more drag/pull on the rope, and so on.

Basically, the snake/rope is practically perforated along that line, and easy to tear free at that point. It's not until it gets sucked into moving parts that it's likely to get chopped up.

[Petah78]

Just my 2c - but I didn't read the question about tracking as an admonishment. As a fellow GR86 owner the same question occurred to me simply as a "how does their driving compare to mine" kind of thing. It's natural to assume that the harder it's driven the sooner the problems appear.

Maybe if it's sped up by driving hard it's slowed down by driving less. Part of me thinks the smart move is to flog it and try to get it to fail quickly so you get on the list for a new short block sooner, and part of me thinks the smart move is to keep the miles low and drive nicely so you get in on the (probable) recall repair and have the car OOC for a couple days instead of weeks/months.

The biggest difference between the two for me is just having to deal with another break-in period.

Oh, and to the question about why the bead comes off as one long snake - that's a function of the way the material is shaped. When you squish too-large a bead of sealant between two flat surfaces and create that rope/snake on the inside edge the weakest point is where it meets the part of itself that's squeezed between the two surfaces. You have a sealant gasket between those two parts that prevents leaking, and then you have fat bead attached to the inner edge that has a lot more strength and surface area than the rest. As fluid moves past it there's a small amount of force applied. If there's enough movement, or enough "rope" surface area to create enough force to begin to pull it away from the thinner "gasket" part of itself you begin to multiply the problem. A gap appears and that rope not has even more surface area and can be pulled into the deeper parts of the fluid current where there's more flowrate. This pulls more of the rope away from the gasket, which creates more drag/pull on the rope, and so on.

Basically, the snake/rope is practically perforated along that line, and easy to tear free at that point. It's not until it gets sucked into moving parts that it's likely to get chopped up.

I agree that driving it harder will definitely expose the problem sooner, if there was one to begin with. With a partial blocked pick up, the oil pressure might still be suffice to meet the demands of the low RPM operations. But that will not be the case for high RPM use. It can be a very slow death for someone who never flogs their car pending on how bad the block is.

I wonder if this will actually be a recall item. That is a lot of labor for something that "might" be a problem. I think TCOAT mentioned that this was a incident with the early 2013 cars, did they ever do a recall on then?

[toeout]

Originally Posted by Spektyr

Just my 2c - but I didn't read the question about tracking as an admonishment. As a fellow GR86 owner the same question occurred to me simply as a "how does their driving compare to mine" kind of thing. It's natural to assume that the harder it's driven the sooner the problems appear.

I agree completely and I had plans on tracking it, just hadn't had time yet. On the replacement motor or a car I plan to be on the rev limiter more, not less.

Also, I was on rev limiter or very close to it when the damage occurred.

[Sasquachulator]

IS this considered a design flaw?

Seems like they designed the sealant area with a very tight tolerance...which is usually ideal is it not?

I guess its just the nature of the sealant, just like in CPU's where you only need to place a dab of thermal past on the center of the CPU before placing the heatsink/fan, and not a whole goop covering the entire CPU....which actually performs worse for heat transfer.

[Petah78]

Originally Posted by toeout

I agree completely and I had plans on tracking it, just hadn't had time yet. On the replacement motor or a car I plan to be on the rev limiter more, not less.

Also, I was on rev limiter or very close to it when the damage occurred.

Do you have confirmation for the demise of your engine? Blocked oil pick up? Or its still being investigated by the dealer?

[Stonehorsw]

Would blackstone oil check be able to verify that before a bigger failure?

[MyHybridBurnsGasAndTires]

^You should be able to see any chunks of sealant in the oil...however it does look like most of this stuff is light enough it's getting pulled up into the pickup and not lingering in the pan.

[NoHaveMSG]

Originally Posted by Stonehorsw

Would blackstone oil check be able to verify that before a bigger failure?

Possibly, but if you are getting excess bearing material in the oil you are probably already screwed.