long winded and wandering comments
After having lived through a bunch of blown up Honda D16A1 engines (1988 acura), I have these comments
Baffled oil pan or an accusump. This seemed to solve many of our rod bearing failures. Why? We too filled over by 1 quart also in a stock pan. Looking at our bearings after the races they showed no Babbitt material, and had a mottled appearance. This as I have learned is evidence of cavitation (bubbles in the oil which pop and strip the metal). So my guess was we were foaming the oil at some point in the lap and that would then lead to bearing failure. The baffled pan keeps the oil from sloshing so much and decreases foaming (?). Accusump provides oil when sloshing in long corners, and a place for the extra 1-3 quarts to reside normally so no foaming (??)
we could tell when the bearings were failing as the temp climbed fast, when otherwise it was stable at about 160F
Clogged up oil pick up. Have you looked at the oil pick up? do you use any RTV like sealant on the engine that could migrate into the oil pick up? RTV will soften at temp and then stick to the pick up screen, limiting oil flow. we had a problem when we tried to use Hylmar as a sealant for a copper head gasket. it clogged the oil pickup and the engine only lasted 5 laps.
The 225 Slant 6 in the 1972 Valiant had severe overheating problems in its first 3-4 races. we drove slower to keep the temps down. We probably suffered a rod bearing minor failure due to heat once. Engine temps as measured on the normal head temp gauge were in the 220F range and we would be boiling over. Was this due to block clogging from radiator sealants?? The rear block drain hole was clogged with some crap, implying the bottom of the block was filled with ~1" of stuff?
I added 2 temp gauges, one on the block and one on the head to watch those temps. A climbing block temp indicates an oiling problem which we saw when our oil pump drive gear was failing last Sept. We stopped the car before the bearings failed, but still did some damage and the car would only run for about 20 minutes before it started knocking after we put in another oil pump.
For march we built a new engine. The new replacement engine block was soaked a couple days with muriatic acid (from a pool store) in the cooling passages before assembly. So we think the inside of the block is clean. This plus a Jeep grand cherokee V8 Radiator now keeps the engine temps down to ~170-180 under hard racing 100% per lap. engine ran the full race with no issues and will hopefully run Sept with no issues. new engine runs 50 psi oil cold and hot. So 35 pSI seems problematic?? Bad Oil pumps? bad cam drive gears (our failure).
I drilled a tiny 1mm hole from the oil pump high pressure area, in through the block to oil the cam/pump drive gear. That probably dropped the oil pressure 5-10 psi overall, but its oiling a known problem for the Slant 6 (talked to the expert Doug Dutra!)
Looking at the pictures of the rods, it looks like the rod is failing, not the bearing. I have fried rod bearings so bad it melted. This does not look melted. there is minimal heating of the rod ends that I see.
!!!! Look closely at the fracture area of the breaks. which one (the rod center, or the big end pieces) has a clean virgin break vs some area that is polished by hammering. The hammering would indicated a failure that was happening over some time (might only be seconds).
if the rod breaks in the middle and the end swings around the surface of the break might look virgin, or might have been hammered by hitting the block (corners pounded?)
If the rod comes apart at the big end and then gets beat to death by the crank, and then fails the center of the rod, that might look different.
The fact that there are 4 pieces to the big end, implies to me that the rod end failed, but why?
thinking, thinking........
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