Bearings knocking, suspected cause excessive oil pressure?

[Blackmk3]

So starting getting rod knock in my supra, was only knocking on start-up until it received full oil pressure, then knock went away. Pulled motor anyway

Attached are the pictures of the big end and mains bearings. These big end bearings were put into my car 4-years ago and done around 20 days at the track and 5000ish kms of city driving. They wernt clearanced (yes i know, i was in a rush and didn't have plastiguage). The main bearings are toyota original. At the same time of fitting the new big ends i shimmed the oil pump, With a typical toyota nut which is approximately 5.5mm thick. I hear people say between 5-7mm shim so figured sweet that will do

A diesel mechanic friend of mine inspected the bearings and he thought that the pitting and the hole in the bearing caps was caused buy excessive oil pressure, damaging the bearing surface over time and eventually digging a hole in the bearing
No 5 is the worst shell with the biggest hole, the cap side is the left side, the other image is no 2 cap side on left side also

Or could it be a clearance issue? Hence why im asking the knowledgeable community of supramania
The catch is that i dont have a oil pressure guage on the car, only the crappy standard one. so its impossible to know what it ran pressure wise

Now for reference the car has a full oil filter relocation setup with a oil thermostat and a big oil cooler, turbonetics turbo, manifold upgrades. 12psi. stock ecu

Thanks very much
Nick

 

[QWIKSTRIKE]

So starting getting rod knock in my supra, was only knocking on start-up until it received full oil pressure, then knock went away. Pulled motor anyway

Attached are the pictures of the big end and mains bearings. These big end bearings were put into my car 4-years ago and done around 20 days at the track and 5000ish kms of city driving. They wernt clearanced (yes i know, i was in a rush and didn't have plastiguage). The main bearings are toyota original. At the same time of fitting the new big ends i shimmed the oil pump, With a typical toyota nut which is approximately 5.5mm thick. I hear people say between 5-7mm shim so figured sweet that will do

A diesel mechanic friend of mine inspected the bearings and he thought that the pitting and the hole in the bearing caps was caused buy excessive oil pressure, damaging the bearing surface over time and eventually digging a hole in the bearing
No 5 is the worst shell with the biggest hole, the cap side is the left side, the other image is no 2 cap side on left side also

Or could it be a clearance issue? Hence why im asking the knowledgeable community of supramania
The catch is that i dont have a oil pressure guage on the car, only the crappy standard one. so its impossible to know what it ran pressure wise

Now for reference the car has a full oil filter relocation setup with a oil thermostat and a big oil cooler, turbonetics turbo, manifold upgrades. 12psi. stock ecu

Thanks very much
Nick

View attachment 71432View attachment 71433View attachment 71434View attachment 71435

In the case of your diesel mechanic friends analogy my daily 140+ psi oil pressure on cold start ups should have caused my berings to hurl 14 years ago when I 1st shimmed my oil pump and relocated the filter. Pitting will come from impurities in the oil which could come from being rich, and detonation. Yes, detonation if you detonate the rods hammer the 1st then in direct line of fire.....your berings. Over a period of time the rod journals may become egg shaped and spin a bering or the bering may be hammered until it spins free causing instant rod knock. Once a bering interacts with the crank, or rod the protective coated film is eroded away and each recurring impact, and impurities can cause pitting. Impurities like moisture can also cause pitting if the oil does not heat up enough to burn of the impurities.

I'd wager your friend never considered tuning as a possible problem to your situation. Id say you need better engine control, and a better tune. Possibly better oil like synthetic oil, and more frequent oil changes. I use Mobile 1 15w50 since 1993 when I 1st bought my Supra, and believe in its longevity properties for a turbo charged engine.

http://www.bobistheoilguy.com/bearingwear/bearingwearanalysis.htm

http://catalog.mahleclevite.com/bearing/

 

[Blackmk3]

Sorry i did forget to mention
As the car is circuit raced i do keep onto the oil, always make sure that its topped up. However i do run a semi-synthetic 15w40. In new zealand average ambient 10-20 Celsius
Sump and pickup is stock however, I do run semi-slick tyres at the circuit but the circut is flat no big hills or cambered corners. i have thaught maybe oil starvation could be a potential?
The car is still running on the stock toyota ecu stock MAF and injectors no lexus trickery, so no issues with knocking. I always use 98 octane fuel (its pump available here)
And the head gasket is in good shape, no moisture in the oil. Never overheats, Never uses or pushes water from the overflow tank. Even on the circuit

 

[Poodles]

I'd say it looks like oil starvation and possibly debris (second pic). High g-forces could absolutely cause oil starvation issues...

 

[QWIKSTRIKE]

I'd say it looks like oil starvation and possibly debris (second pic). High g-forces could absolutely cause oil starvation issues...

I did not look at those pictures....it does look like starvation. those little pits is probably from debris from the crank.

 

[Blackmk3]

Hmmm i was thinking it was about time to modify the sump and pickup, Great well thanks very much for the input guys
Thankfully the crank is still fine there's a few very small lines on it but ill clean it up with some linishing paper and give it the measure over

 

[mk3racer]

Have you been monitoring engine oil temperature? If so how high has it gotten on the track? What type oil cooler are you using?


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