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

[NoHaveMSG]

Originally Posted by KillerBMotorsport

If you pull vacuum on the crankcase, the PCV valve on the block will close. It's the other one that needs to be plugged or pinched closed.

I was just commenting on the location. I don't think trying to blow back through the system is going to do anything practical. Visual inspection and removal is the only practical solution I see for this issue.

[Tcoat]

Originally Posted by NoHaveMSG

I was just commenting on the location. I don't think trying to blow back through the system is going to do anything practical. Visual inspection and removal is the only practical solution I see for this issue.

The only way I would be comfortable with blowing it out would be to take each individual piece off and inspect and blow through it. At that point it would be easier to see if it blew up and just replace it!

[Tcoat]

Originally Posted by Ultramaroon

Just run the engine backward

[KillerBMotorsport]

Sucking the drain with a vacuum is going to do less than tipping the car a few degrees on uneven jackstands or ramps. Pulling a vacuum on a closed system gives no flow. Put a penny in the tube, your hand over the end of the shop vac, and anything in the tube will not towards the vacuum.

The only way to make the vacuum method work, would be to remove the oil pump, so you have flow to the vacuum.

[KillerBMotorsport]

Originally Posted by NoHaveMSG

I was just commenting on the location. I don't think trying to blow back through the system is going to do anything practical. Visual inspection and removal is the only practical solution I see for this issue.

Agreed.

The other thing no one knows, is if this RTV shedding is only temporary from loose bits at initial startup/break-in, or if the RTV deteriorates and breaks down over time, and is ongoing to some (hopefully lesser) extent.

Talked to a lot of BRZ/GR guys at Boxerfest this weekend and a few of them of them had dropped their pan and inspected the pickups, with no silicone inside. So that was good to hear.

[Tcoat]

Originally Posted by KillerBMotorsport

Agreed.

The other thing no one knows, is if this RTV shedding is only temporary from loose bits at initial startup/break-in, or if the RTV deteriorates and breaks down over time, and is ongoing to some (hopefully lesser) extent.

Talked to a lot of BRZ/GR guys at Boxerfest this weekend and a few of them of them had dropped their pan and inspected the pickups, with no silicone inside. So that was good to hear.

Most is probably what get pinched off when the parts are torqued down but some of course can still break off with time.

Good to hear there are some without concerns since we will only see all the horror stories. The same one over and over, and over, until the problem seems way more common than reality.

[JusTheG]

Originally Posted by KillerBMotorsport

Agreed.

The other thing no one knows, is if this RTV shedding is only temporary from loose bits at initial startup/break-in, or if the RTV deteriorates and breaks down over time, and is ongoing to some (hopefully lesser) extent.

Talked to a lot of BRZ/GR guys at Boxerfest this weekend and a few of them of them had dropped their pan and inspected the pickups, with no silicone inside. So that was good to hear.

Nice to hear about the responses of people who have not seen any RTV trapped within the pickup filter. Most likely what has happened and needs to be confirmed by Subaru was with early production builds that the RTV pattern was not dialed into the exact dispense weight.

Honestly, you can waste a lot of time trying to tune RTV dispense through the dispense head, pump, flow characteristics of the system (hoses, type of hose material for pressure buildup, clamping), flow meter system (inline or external), dispense nozzle for bead width, valves for mitigated stringers (snuff-back), dispense speed, pump motor speeds, and finally the material itself for specific weight to characterize with a SPC/GRR analysis. And you still won't be able to mitigate all defect at the dispense head. Man, I have seen so many tests for these systems that I honestly am surprised with the variations for dispense systems that ultimately affect each of these variables differently. Air motors, hydraulic rams, internal electric motors, hot melt pumps, large bucket rams, two-part mixers; ALL these systems have their pros and cons.

Regardless of how inconsistent the dispense is, RTV is not a big problem to worry about entirely. Just remember that the silicone will degrade over time because of thermal loading and vibration that will eventually separate the intermolecular bond between the two metal surfaces. Hence the small particles people showed in their videos after disassembly. Still, these RTV materials are no joke as they will hold items together for years and not suffer extreme separation. I had to take a 25-year old module that needed Remanufacturing, and that sucker had the RTV still stuck to the connector even when pried apart with Isopropanol and CO2 blasting to separate the bead. After RTV dispense and passed leak test, that 25-year old module was back to a car that needed the part (expensive part at that).

My only concern is when you have lubricants needing to flow from the oil pan and you have these 1-part RTV adhesives blocking some of the flow. The RTV can reflow (become fluid-like) with enough heat and oil applied to separate the water molecules binding it together, but the likelihood of it is very low even after multiple thermal cycles. My only desire from these scenarios is making sure Subaru handles the appropriate means to reduce dispense defects and ensure clarity to customers if they file warranty concerns. No engineer wants to see a car die because of deficiencies in the manufacturing, so I'm optimistic you won't see these issues be more prevalent.

[NoHaveMSG]

Originally Posted by JusTheG

Nice to hear about the responses of people who have not seen any RTV trapped within the pickup filter. Most likely what has happened and needs to be confirmed by Subaru was with early production builds that the RTV pattern was not dialed into the exact dispense weight.

Honestly, you can waste a lot of time trying to tune RTV dispense through the dispense head, pump, flow characteristics of the system (hoses, type of hose material for pressure buildup, clamping), flow meter system (inline or external), dispense nozzle for bead width, valves for mitigated stringers (snuff-back), dispense speed, pump motor speeds, and finally the material itself for specific weight to characterize with a SPC/GRR analysis. And you still won't be able to mitigate all defect at the dispense head. Man, I have seen so many tests for these systems that I honestly am surprised with the variations for dispense systems that ultimately affect each of these variables differently. Air motors, hydraulic rams, internal electric motors, hot melt pumps, large bucket rams, two-part mixers; ALL these systems have their pros and cons.

Regardless of how inconsistent the dispense is, RTV is not a big problem to worry about entirely. Just remember that the silicone will degrade over time because of thermal loading and vibration that will eventually separate the intermolecular bond between the two metal surfaces. Hence the small particles people showed in their videos after disassembly. Still, these RTV materials are no joke as they will hold items together for years and not suffer extreme separation. I had to take a 25-year old module that needed Remanufacturing, and that sucker had the RTV still stuck to the connector even when pried apart with Isopropanol and CO2 blasting to separate the bead. After RTV dispense and passed leak test, that 25-year old module was back to a car that needed the part (expensive part at that).

My only concern is when you have lubricants needing to flow from the oil pan and you have these 1-part RTV adhesives blocking some of the flow. The RTV can reflow (become fluid-like) with enough heat and oil applied to separate the water molecules binding it together, but the likelihood of it is very low even after multiple thermal cycles. My only desire from these scenarios is making sure Subaru handles the appropriate means to reduce dispense defects and ensure clarity to customers if they file warranty concerns. No engineer wants to see a car die because of deficiencies in the manufacturing, so I'm optimistic you won't see these issues be more prevalent.

I run into stupid issues like that with our low pressure injection molding machines. You change something like a pump motor and it’s spinning 10-20rpm off and the shot weight goes off a gram or two and it creates all sorts of problems.

[JusTheG]

Originally Posted by NoHaveMSG

I run into stupid issues like that with our low pressure injection molding machines. You change something like a pump motor and it’s spinning 10-20rpm off and the shot weight goes off a gram or two and it creates all sorts of problems.

Agreed, and the worst part is when it's the same motor - rating, part number, manufacturer - and the tuning forces it to be recalibrated to work with the specific density of the material. I swear people were calling me crazy when I had 1 single Amplifier mess my whole dispense system (granted it was for conformal coating for OEM PCB's) that I had to retune, reteach, and setup the dispense pattern for 1 product. My operators hated the downtime for the equipment, but it ran smooth as a champ for 3 months of non-stop production till the product went End of Life and the equipment was scrapped. No one in my plant wanted to touch that machine with a 10 ft pole, and even after it was scrapped no one wanted anything to do with that equipment.

The maintenance intervals, typical wear times, and especially changeovers always make equipment run with variation. It's very hard to get it done right the first time, so all depends on is continuous improvement to get it down to as close of a σ that you can with your dispense weights. Rest assured, I know how much suffering being at Tier 1 or 2 specs that makes the pain for manufacturing understandable. But it's because of the common issues we see at plants that I know other manufacturers like Subaru will ensure quality to prevent future recalls/problems.

[Sport-Tech]

Thanks guys, very interesting to get such insider knowledge!

[Blighty]

Originally Posted by KillerBMotorsport

Talked to a lot of BRZ/GR guys at Boxerfest this weekend and a few of them of them had dropped their pan and inspected the pickups, with no silicone inside. So that was good to hear.

Great to read. I think a few youtubers we're going to ask a few people as well, so will be good to see those interviews.

[chipmunk]

As long as the RTV is fully cured (at least 48 hours with at least 50% relative humidity) silicone shouldn't breakdown. Nor is it soluble in petroleum based liquids.

[toeout]

I got the car back from the dealer with the new engine. The invoice confirmed that the failure was due to the RTV blocking the oil pickup.

[mycrors7]

Originally Posted by toeout

I got the car back from the dealer with the new engine. The invoice confirmed that the failure was due to the RTV blocking the oil pickup.

i still dont believe the clogged pickup only damaged a single rod bearing

blocked pickup would damage all 4 bearings to some extent.

any way you can ask the dealer to check the other rod bearings for damage?

iirc, there's 3 failures that are all related to a cyl 1 rod bearing