Engine locked up?

HOW CAN THE ENGINE LOCKED UP?

Hi Last week My car engine light came on, I towed my vehicle to dealer and he told me drain plug is missing and no oil in engine becasue of which engine seized, I went back and spoke to NTB where I got my oil change doen about 4 month back and they filed a case with insurance and insuarcne denied my claim stating the reason for engine failure is
"There is an isolated failure of the #3 rod bearing with subsequent damage to the engine from metal contamination. There is no heat discoloring to indicate a lack of lube condition"
But Toyota states
this " Found Drain plug missing and oil residue all the way to the rear, car must have been at highway speed when plug came out, after getting approved to tear down found bearing failure on #3 from lack of oil, also found cams and journals scared when adjuster got here we pulled car in and raised it and oil was still dripping from rear rear struts evidence that it lost oil at highway speed due to drain plug coming out. ".

Please let me know can a drain plug come out after 4 months and can a # 3 bearing fail on its own with 39000 miles and I have maintained my engine very well and have done all oil change on time.

Hi rasmataz,
Thanks for your reply, but i am not form mechanical background so could understand you could please elaborate.
here is the complete NTB report.
"The technician removed all the cam caps and there are lightly scored. The camshafts journals are lightly scored. There is no discoloring to the camshaft journals or caps. There is no scoring or discoloring to the camshaft lobs or lifters. The technician removed all the rod caps and the #1, #2 and #4 rod bearings are scored. The #3 rod bearing has spun and is missing. There is no heat discoloring to the rod caps or rod journals of the crankshaft. The #2 and #4 rod bearings are pitted. There is a lot of metal in the oil pan. There is large metal pieces in the oil pick up screen, but the screen is not blocked. The oil pan has a new drain plug installed and is tight. The technician states there is no damage to the oil pan drain plug threads. There is no impact to the oil pan. The oil filter is not new and does not appear to be leaking. The oil filter is a PZ-21, yellow in color. There is no sludge seen. There is oil blow back from the engine to the muffler. The technician states there was no oil or drain plug when the vehicle came in but the inspector can not verify this. No other damage or failures noted at this time
"
Cause of Failure
There is an isolated failure of the #3 rod bearing with subsequent damage to the engine from metal contamination. There is no heat discoloring to indicate a lack of lube condition. There is no verified failure of the oil pan drain plug at the time of this inspection.

They are denying my claim stating there was no heat discoloration and and it don't take 4 month with 1900 miles driven between the oil change for the drain plug to fell out.

Toyota says if the drain plug was hand tighten then it might take a while for it to come out, and since i didn't drive the vehicle as soon as i saw the engine light, there is not heat discoloration if i would have driven then there should have been heat discoloration.

I have picture which shows oil leakage all the way from front to rear.

Do you think NTB is right or Toyota???? Since NTB is denying my claim i am not sure what to do?

Engine Mechanical problem
2000 Toyota Corolla 4 cyl Four Wheel Drive Automatic 107K miles

Hi ,

I bought my car for 4700$. My car engine seized because of lack of engine oil a month after i bought my car. I do not understand how my engine could run out of oil in a month, when i got my car checked before i bought it. Can you please tell me, if it is worht repairing my car now, The cheapest estimate i got so far is 2400$ for replacing my engine. your advice will be helpful. My car body is good.

Hello thankyou for your reply, I checked for engines in junkyards and like you said they give warranty for the part and not the labor of installation. And they are not priced any lower than what my mechaniic suggested me.

I guess what I was asking was is it worth repairing my engine? And I guess what I got from your answer is you are sugessting I replace my engine. If thats what you are suggesting me, please let me know.

Thankyou

sonia