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

[Blighty]

Originally Posted by NoHaveMSG

Right back to where we were pages ago.

Heh. That's exactly right. Good way to end it.

[dragoontwo]

Originally Posted by Ronac

He probably added more silicone than was there in the first place…

Also, the silicone that gets stuck in the pickup doesn’t only come from the oil pan. It can come from the front timing cover mating surface as well. It can continue to break off from there and plug up the pickup.

Also from the mid pan assembly bolted to the block.

[Tcoat]

Originally Posted by dragoontwo

Also from the mid pan assembly bolted to the block.

This^

And various other plates, accessories, etc, etc.
Everybody is so fixated on what is found on the pickup they are ignoring all the other places sealant is used. If excess is breaking off other parts, especially after the filter, then the pickup, although the obvious choice may be meaningless.
It would only take a piece the size of a pinhead to be lodged in the wrong oil passage to starve a single bearing to the point of spinning. You wouldn't even see a drop in oil pressure or have any other warning signs at all.
This is EXACTLY what was found to be happening in many of the pre-recall FA20s that spun bearings. At that time everybody still wanted to find something else even with all the evidence at hand and I see that this is going to go the same route.

See those other colours? How much of the post filter oil journals did they pass through before ending up back in the pan?


One of about 30 pre recall failures involving sealant.
https://www.ft86club.com/forums/show....php?p=2696906

[Petah78]

Originally Posted by Tcoat

This^

And various other plates, accessories, etc, etc.
Everybody is so fixated on what is found on the pickup they are ignoring all the other places sealant is used. If excess is breaking off other parts, especially after the filter, then the pickup, although the obvious choice may be meaningless.
It would only take a piece the size of a pinhead to be lodged in the wrong oil passage to starve a single bearing to the point of spinning. You wouldn't even see a drop in oil pressure or have any other warning signs at all.
This is EXACTLY what was found to be happening in many of the pre-recall FA20s that spun bearings. At that time everybody still wanted to find something else even with all the evidence at hand and I see that this is going to go the same route.

See those other colours? How much of the post filter oil journals did they pass through before ending up back in the pan?


One of about 30 pre recall failures involving sealant.
https://www.ft86club.com/forums/show....php?p=2696906

I was going to ask why are there other colors in some the few JDM pics that i have seen? Most of the ones are all grey in color. Do we know if other color RTV were used by Suby during assembly? I actually see this as a good sign, at least the colored RTV breaking off appears to be minimal cases, for now. Less problem areas, but could be wishful thinking.

While i am not an engineer, I was looking at the design of the FA24's pickup and compared to the FA20, the FA24 is a much better design to handle blockages. It has more surface areas where it can draw oil from. Really makes me question if partial blockage is really that big of a concern, assuming the car was no low on oil.

[RZNT4R]

Originally Posted by timurrrr

From the maintenance schedule:
"Engine oil and oil filter. Severe driving conditions [...] Replace every 3750 miles or 3.75 months, whichever comes first."

I don't know how "severe" I'd consider autocross, but personally I wouldn't recommend driving for 5500 miles on factory oil. I changed mine at 1040 miles, right before my first autocross.



Or log data, especially if you're saying it should be tested on the track anyways.

The verbiage for "Severe" varies a lot by manufacturer, but generally, it's anything that isn't "normal driving on city streets". Usually, any sort of sustained increased load, trailer towing,sustained high speed, sustained low speed, hills, constant stop and go, a roof rack, wide temperature changes, high RPM operation, dusty conditions, etc.

No way would my car EVER have the factory fill past 5000 miles, My factory oil got dumped at 1000km, and then at the 6000km "regular interval first oil change" it got drained again along with the gearbox and differential gear oils. So far oil has never stayed in there more than 6000km and the gear oils were changed again at 24000km and just now at 48000km.

Further, no way would my car ever be tracked on 0W20. That's dish water meant for getting groceries.

[Tcoat]

Originally Posted by Petah78

I was going to ask why are there other colors in some the few JDM pics that i have seen? Most of the ones are all grey in color. Do we know if other color RTV were used by Suby during assembly? I actually see this as a good sign, at least the colored RTV breaking off appears to be minimal cases, for now. Less problem areas, but could be wishful thinking.

While i am not an engineer, I was looking at the design of the FA24's pickup and compared to the FA20, the FA24 is a much better design to handle blockages. It has more surface areas where it can draw oil from. Really makes me question if partial blockage is really that big of a concern, assuming the car was no low on oil.

There are numerous plates, cover and other parts sealed with different colours of sealant.
The coloured is more of a concern than the attention it is getting. Yes it was grabbed at the pickup but how much of the engine did it travel through before it made it to the pan? Even worse is how much of the engine did it NOT travel through? How small a piece does it take to plug the channels leading to this hole?


For that matter if it is a plugged pickup reducing pressure why does only one bearing have damage? If pressure is reduced to the point of failure it should not be isolated to one singe part.
Not saying plugged pickup didn't play a part. If small pieces are present then with full pressure they may be fine but even a slight reduction would have a greater impact.

[NJ10]

Originally Posted by Aon

This is a response received by one of the journalists from Toyota:

@Aon

Was this published somewhere? Could you link us to the source for this?

[RZNT4R]

Originally Posted by Tcoat

There are numerous plates, cover and other parts sealed with different colours of sealant.
The coloured is more of a concern than the attention it is getting. Yes it was grabbed at the pickup but how much of the engine did it travel through before it made it to the pan? Even worse is how much of the engine did it NOT travel through? How small a piece does it take to plug the channels leading to this hole?


For that matter if it is a plugged pickup reducing pressure why does only one bearing have damage? If pressure is reduced to the point of failure it should not be isolated to one singe part.
Not saying plugged pickup didn't play a part. If small pieces are present then with full pressure they may be fine but even a slight reduction would have a greater impact.

Ideally, no piece of RTV should ever go past the oil filter which is right after the oil pump.

HOWEVER.

If you are using a low quality oil filter with a bypass valve that does not seal well, bad filter media design or assembly OR if the filter media is full (like after a long interval with break-in oil) and the bypass is forced to open under high pressure/high flow conditions (high RPM), then stuff can get past the filter.

[NoHaveMSG]

Originally Posted by Tcoat

For that matter if it is a plugged pickup reducing pressure why does only one bearing have damage? If pressure is reduced to the point of failure it should not be isolated to one singe part.
Not saying plugged pickup didn't play a part. If small pieces are present then with full pressure they may be fine but even a slight reduction would have a greater impact.

That is a good point. Assuming the FA24 is structured similarly to the FA20, the #2 and #3 rod share oiling from the same main while 1 & 4 are feed from their own mains. If it was an in general oil pressure loss I would expect one of the two center rods to eat the bearing first. For reference though, I did lose only the #3 on an FA20 during total oil pressure loss.

[Petah78]

Originally Posted by RZNT4R

Ideally, no piece of RTV should ever go past the oil filter which is right after the oil pump.

HOWEVER.

If you are using a low quality oil filter with a bypass valve that does not seal well, bad filter media design or assembly OR if the filter media is full (like after a long interval with break-in oil) and the bypass is forced to open under high pressure/high flow conditions (high RPM), then stuff can get past the filter.

I am not sure how the oiling in a FA works but that will only be true if the RTV can only break off BEFORE the oil filter. Is there any RTV used post filter that will travel into the crank journals?

[RZNT4R]

Originally Posted by Petah78

I am not sure how the oiling in a FA works but that will only be true if the RTV can only break off BEFORE the oil filter. Is there any RTV used post filter that will travel into the crank journals?

I don't think so. There is some under the cam carrier so a REALLY sloppy application could send some in the VVT oil filter screens, but case-halves oil passages should use o-rings, like the timing cover oil passages, as any sort of RTV is typically not used in pressurized applications.

[KillerBMotorsport]

Interesting to see Subaru change the pickup, and it definitely has far more screen area (although not as free flowing as the wire) than the FA20.

Here's few pics of what happened to our 2015 FA20 WRX test mule...

The pickup was pulled after a catastrophic failure, but there was some phantom knock leading up to this point (for a subtle split second at startup). The assumption was that a spun bearing was likely in our future. The pickup had mostly silicon stuck to it but also metal.




The larger pump on the WRX FA20, higher weight oil, and abuse (450whp and higher redline) has its way with the brittle tack welds on the OEM pickup screen.



The last morning it started, engine failure came nearly instantly, since the oil filter bypass is open when the oil is cold. All it takes is one small piece of metal to pop the fragile PM Oil Pump gears and then things go from bad to worse in very short order.

[Tcoat]

Originally Posted by RZNT4R

Ideally, no piece of RTV should ever go past the oil filter which is right after the oil pump.

HOWEVER.

If you are using a low quality oil filter with a bypass valve that does not seal well, bad filter media design or assembly OR if the filter media is full (like after a long interval with break-in oil) and the bypass is forced to open under high pressure/high flow conditions (high RPM), then stuff can get past the filter.

Not a matter of it getting past the filter but of being introduced after the filter. There is sealant used between the filter and the pan. Anything coming from those sections have to pass through the engine to make it back to the filter to be caught.

[FrickingReallySlow]

Bypass of the filter doing it’s job in cold cold starts is that it opens the filter like it should. Everything during that time won’t get filtered. Different filters all have different pressure range difference between input and output where it opens

Originally Posted by RZNT4R

Ideally, no piece of RTV should ever go past the oil filter which is right after the oil pump.

HOWEVER.

If you are using a low quality oil filter with a bypass valve that does not seal well, bad filter media design or assembly OR if the filter media is full (like after a long interval with break-in oil) and the bypass is forced to open under high pressure/high flow conditions (high RPM), then stuff can get past the filter.